WW-00545     Reviewed 1997  

Trees, Shrubs & Vines For Minnesota Landscapes

S H R U B S

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ALPINE CURRANT (see CURRANT)

AMUR MAPLE

Amur Maple (Acer ginnala), 10-15 ft., is a fast-growing versatile shrub, It is tolerant of infertile soils, dry sites, and partial shade, but intolerant of poorly drained soils. Fall color is intense, usually in shades of red, but also yellow and orange. This plant is useful for shrub borders, formal and informal hedges, specimen plants, small trees, shelterbelts, and windbreaks. Zones 3 and 4.

 

ARROWWOOD

Arrowwood (Viburnum dentatum), 7-10 ft., is a shrub that is tolerant of some shade and can tolerate a wide range in soil moisture. It has white clusters of flowers followed by fruits in pendant clusters that turn deep blue at maturity. During the summer the foliage is a clean, dark green; it turns a purple-red in the fall. Zones 3 and 4.

 

AZALEA (see also RHODODENDRON)

Azaleas are new to Minnesota and have considerable potential for use in Minnesota landscapes. They require an acid soil that retains moisture yet is adequately drained. Nonacidic soils can be modified by mixing in acid peat moss or by replacing the soil prior to planting. Azaleas do best in full sunlight, but benefit from some shade during the hottest part of the day. Plants seem to benefit from a generous organic mulch. Azaleas and rhododendrons should be moved with soil attached to the roots, either potted or as balled and burlapped plants.

Exbury Hybrid Azaleas (Rhododendron, Exbury hybrids), 4-8 ft. There are many named selections in this group, with a wide range of colors available. The hardiest selections at the arboretum bloom at best only two or three years out of five. Enclosing the plants with chicken wire and filling the space with loose leaves such as oak protects the flower buds and makes it possible for them to bloom. Zone 4.

Northern Lights Azalea (Rhododendron 'Northern Lights'), 7-10 ft. These hybrid azaleas developed by the University of Minnesota Landscape Arboretum have flower buds that withstand winter temperatures throughout the state. There is a slight variation in color, plant size, and growth among Northern Lights azaleas. The fragrant flowers range in color from light to bright pink. Bloom lasts 7 to 14 days depending on the weather. Hardy in zones 3 and 4 without protection.

Mollis Azalea (Rhododendron x kosteranum), 5-7 ft. Plants sold by local nurseries are grown from seed of a strain that is hardier than most strains of the mollis azalea. The color varies slightly, but most are in shades of orange. Flower buds of the Minnesota strain of the mollis azalea suffer injury at temperatures of -15° to -20°F. To some people the flowers have a musty odor. Plants are vigorous and have somewhat coarse foliage. Adapted to the southern half of zone 4.

 

BARBERRY

Barberries belong to a large genus, with only a few species that are hardy in Minnesota. None of the evergreen types is hardy. Many are barred from importation into this country because they are alternate hosts for the stem rusts of small grains.

Barberries are adapted to a wide range of soils. Most have a good fall color. In Minnesota most are subject to slight tip kill or more severe winter injury. Their sharp spines make pruning somewhat difficult.

Japanese Barberry (Berberis thunbergii), 3-4 ft. This species is usually hardier than most of the clones of the Japanese barberries, although its tips can be killed during the winter. During the summer the foliage is dark green, but often takes on a showy, bright red fall color, It has many elongated, bright red fruits, ½ inch in length, that are retained into the winter. Adapted to zone 4; trial in zone 3.

CRIMSON PYGMY BARBERRY (Berberis thunbergii 'Crimson Pygmy'), 1 ft., has a spread up to 3 feet. In Minnesota it will often suffer winter tip injury or be killed nearly to the ground. After pruning it makes a good recovery. It needs a sunny site to produce a good, deep maroon color. It makes a good contrast plant with low spreading evergreens. It should not be planted where the clumps will become contaminated with quackgrass. Like most Japanese barberries, it has sharp spines. Zone 4.

GOLDEN JAPANESE BARBERRY (Berberis thunbergii 'Aurea'), 2-3 ft., is a selection that has clear yellow foliage through the entire summer. Some years the fall color changes to a bright red. At present it is not commonly available because of propagation difficulties. Zone 4; trial in zone 3.

REDLEAF JAPANESE BARBERRY (Berberis thunbergii 'Atropurpurea'), 3 ft., is similar to the Japanese barberry, except that it has a deep maroon color and is slightly less hardy. Zone 4.

Korean Barberry (Berberis koreana), 6-8 ft., is a vigorously growing shrub that has less ridged spines than do other barberries, making it easier to work with. Summer color of the foliage is green, with a red tinge on younger leaves. Fall color varies from a bright red in full sun to a purple-red in partial shade. Flowers are yellow and quite showy, in long pendant clusters. The fruits are green at first and turn bright red in late summer. They remain on the plant through the winter, but are not readily taken by birds. Korean barberry sometimes spreads short distances by suckering roots. Zones 3 and 4.

Picture of a Korean barberry  

BAYBERRY

Bayberry (Myrica pensylvanica), 3-5 ft. This is an uncommon broadleaf evergreen that loses its leaves under Minnesota weather conditions. The glossy, dark green foliage makes this an attractive shrub through the growing season. In early winter the leaves are dark green; by spring they normally turn brown and drop. Bayberry grows well on acid, infertile soils. It is likely to suffer less damage in the winter if planted where it is protected from the winter sun. The small gray berries are produced on female plants beneath the new growth, so they are not visible on the exterior surfaces. Trial in zone 3 and 4, with some winter dieback possible in both zones.

 

BOXWOOD

Boxwoods are broadleaf evergreens that are used extensively in the eastern United States for landscape purposes, but unfortunately there is only a single species that has proved hardy in Minnesota. It should be protected from the winter sun. If planted on the north, west, or east side where there is some shade, it does not have to be wrapped to prevent winter sun injury.

Korean Boxwood (Buxus microphylla koreana), 2 ft. with a spread of 3 ft. The winter color is often an olive to purple-green. The selection Wintergreen holds the green color better than the species. It does best planted where it will be in winter shade. It makes a satisfactory specimen plant and a useful plant for a small hedge. Protected sites in zones 3 and 4.

 

BUFFALO BERRY

Buffalo Berry (Shepherdia argentea), 10-13 ft., is a coarsely branched shrub with narrow, silvery-green leaves. Each plant is of a single sex. The inconspicuous flowers bloom in May. Flowers on female plants are followed by berries that turn a bright red when they ripen in August. The berries can be used for jelly. Indians dried them to use in making pemmican. Birds also eat the fruits. This plant is tolerant of drought and alkaline soil. It should be planted in full sun. Branches end in sharp spines, making it an impenetrable shrub. It sends up some suckers near the parent plant. It is useful in border plantings, shelterbelts, windbreaks, barrier plantings, and for creating thickets for wildlife. Zones 3 and 4.

 

BURNING BUSH

Burning bush (Euonymus alata), 7-10 ft., is a shrub with good foliage and form. The twigs have corky ridges that are quite conspicuous and add winter interest. The elongated red fruits are showy but are seldom produced in large enough numbers to be effective. Previous plantings of the selection Compacta have not been dependably hardy in the Twin Cities area. There is a hardy, compact selection called Nordine, which was introduced because of the abundance of fruits it produces.

The burning bush has dark green, clean foliage during the growing season. In the fall it turns a deep red on sunny sites but in partially shaded areas it often takes on a pink to scarlet color.

Rabbits can severely damage this plant during the winter, often necessitating enclosing young plants with a cylinder of chicken wire. Zones 3 and 4.

Picture of a Burning bush  

BUSH HONEYSUCKLE

Bush Honeysuckle (Diervilla lonicera), 3 ft. This native shrub spreads by underground stems making it useful as a taller ground cover. It is adapted to a wide range of soil conditions, except for poorly drained soils. It grows best in full sun, but is tolerant of partial shade. The leaves are dark green, often with a red tinge. The fall color is often a maroon-red. The yellow flowers are rather inconspicuous. Zones 3 and 4.

 

CARAGANA

Caraganas belong to a large genus containing many species that are mostly shrubs. If trained to a single stem a few species become treelike. Caraganas grow best in sunny locations and are tolerant of dry sites, but intolerant of poorly drained soils. Most have flowers that are yellow and pealike. Although the flowers are small, some are produced in profusion, making the plant showy. The foliage is quite free of insect problems, but is susceptible to leaf spot diseases that can cause premature defoliation. Most species have sharp spines, which make them difficult to work with. They are not bothered by mice and rabbits during the winter.

Some species are useful for shelterbelt plantings while the smaller ones are useful in foundation plantings.

Globe Caragana (Caragana frutex 'Globosa'), 3 ft., is a slow-growing dark green species useful for hedges. It makes a dense, almost formal hedge without pruning. It sometimes defoliates in late summer because of leaf spot. Although this plant has proven hardy in Minnesota trials, it is only now becoming commercially available. For many years it was available only through Canadian nurseries, but it is now being propagated in Minnesota nurseries. Zones 3 and 4.

Littleleaf Peashrub (Caragana microphylla), 8 ft., is similar to Siberian peashrub but it is a smaller plant and the leaves are a darker green. The cultivar Tidy has narrow leaflets and lemon-yellow flowers, making it attractive when it blooms in late May or early June. Hardy in zones 3 and 4.

Pygmy Peashrub (Caragana pygmaea), 5 ft., is a small, upright shrub with fine-textured foliage of dark green color. Flowers are small, yellow, and pealike, appearing in late May or early June. Useful in border or foundation plantings or for a hedge. In the past it has been used mainly in the Red River Valley area. Zones 3 and 4.

Russian Peashrub (Caragana frutex), 5 ft., is a compact suckering shrub that is excellent as a bank cover. The compound leaves are dark green with four leaflets. Zones 3 and 4.

Siberian Peashrub or Peatree (Caragana aborescens), 10-12 ft., is an upright shrub that is drought resistant and tolerant of alkaline soils. The attractive yellow, pealike flowers appear in May. These are followed by small pealike pods. Leaves are subject to leaf spot problems late in the season. This shrub is useful in shelterbelts and windbreaks and is sometimes used for informal hedges. Zones 3 and 4.

WEEPING SIBERIAN PEASHRUB (Caragana aborescens 'Pendula'), 3-7 ft. The size of this plant depends on whether it is grafted at ground level or on a standard to give it a trunk. This novelty is a selection of the Siberian peashrub that is of limited usefulness. It is not commonly available. Zones 3 and 4.

 

CHOKEBERRY

Chokeberries are shrubs that are useful for foundation, shrub border, or wildlife plantings. They do best in full sun. They can tolerate some shade, but growth is slow and sparse. The showy white flowers appear in May but are not pleasantly fragrant. They do best on a well-drained soil.

Black Chokeberry (Aronia melanocarpa), 5 ft. This plant is compact and is a more spreading shrub than the red chokeberry. The flowers are white in fiat clusters, appearing in late May. The fruits are abundant but inconspicuous because of their black color. The foliage is dark green. This is an excellent shrub for foundation and border plantings in sunny locations. Zones 3 and 4.

GLOSSY BLACK CHOKEBERRY (Aronia melanocarpa 'Elata'), 4 ft., differs from the above species in that is has glossy dark green leaves and stays smaller. Zones 3 and 4.

Red Chokeberry (Aronia arbutifolia), 5 ft., is an upright shrub with pinkish white flowers appearing in flat-topped clusters in late May. Fruits are small, round, red, and showy even after the leaves have fallen. The foliage is dark green, turning a brilliant red in the fall. It is safest to plant this species in the southern half of zone 4.

 

CHOKECHERRY

Chokecherry (Prunus virginiana), 13 ft., is not commonly planted as an ornamental, probably because it is such a common native. Chokecherries require a well-drained soil and sunlight. The fruits are attractive to wildlife and can be used in cooking. Adapted to zones 3 and 4.

CANADA RED CHERRY (Prunus virginiana 'Canada Red'), 13 ft., has leaves that emerge green and turn a dark red-maroon after several weeks. Its flowers and fruits are similar to the common chokecherry. Zones 3 and 4.

SHUBERT CHOKECHERRY (Prunus virginiana 'Shubert'), 13 ft., is similar to Canada Red cherry. Zones 3 and 4.

CISTENA SAND CHERRY (see SAND CHERRY)

CLOVE CURRANT (see CURRANT)

 

CORALBERRY

Coralberry (Symphoricarpos orbiculatus), 3 ft., is a shrub that is planted in foundation and border plantings. It spreads by suckers, which makes it useful for bank plantings. The flowers are inconspicuous because of their small size. The berrylike fruits of various sizes are tightly clustered at the tips of branches and in leaf axils. The shrub gets its name from berries that turn a bright red. They are retained on the plant into the winter but turn black after a hard freeze. Zones 3 and 4.

 

COTONEASTER

There are many species of cotoneaster but only a few that are hardy enough for Minnesota. There is a wide range in plant size; some are low ground covers, while others become large shrubs. Most have white or cream-colored flowers that have an unpleasant odor. The mature fruit is red or black, depending on the species.

Fireblight, a bacterial disease, has eliminated most of the cotoneasters in trials at the University of Minnesota Landscape Arboretum. Infection injury varies from tip injury to branch dieback to death of the entire plant. Infection in landscape plantings has not been as widespread as in the arboretum trials. The susceptibility to this disease should be considered before making extensive plantings of cotoneasters.

Cranberry Cotoneaster (Cotoneaster apiculata), 2 ft., is a low spreading shrub with arching branches. It is the hardiest of all the low cotoneasters but often shows winter dieback in exposed sites. The small, shiny green leaves and the bright red, cranberrylike fruits make this an attractive shrub for sites that have dependable winter snow cover. The small flowers are pink. Trial in zone 4.

Hedge Cotoneaster (Cotoneaster lucida), 5 ft., is the most commonly planted cotoneaster in Minnesota. In nurseries it is often incorrectly sold as Peking cotoneaster (C. acutifolia). The leaves are lustrous green and produce an abundance of black fruits. The fall foliage is often red. The hedge cotoneaster is susceptible to oystershell scale as well as fireblight. It is often planted for a formal hedge. Hardy in zones 3 and 4.

Many-flowered Cotoneaster (Cotoneaster multiflora), 8 ft. This species forms a large spreading shrub that may be 12 feet or more wide. It has large white flowers. The abundant fruits are a bright red. It is susceptible to fireblight. Hardy in zone 4; trial in zone 3.

 

CRANBERRY BUSH

Cranberry is a common name applied to two unrelated genera. It is applied to the high bush group included here, Viburnum, and also to the low vining plants that grow in sphagnum bogs, Vaccinium (the commonly eaten cranberry). The latter group is not adapted to upland growing conditions.

The viburnum group is useful for landscape plantings. The shrubs grow best in full sun, but are tolerant of some shade. Most will flower and fruit more abundantly in sunny locations. They are adapted to ordinary garden soils, but will grow on moist sites. Size within this group varies from 2 to 13 feet in height.

American Cranberry Bush (Viburnum trilobum), 7-12 ft., grows taller in shady locations. This native shrub blooms in June with large flat-topped clusters of white flowers. The outer row of sterile flowers is showy while the center consists of small fertile flowers that produce the berries. The berries are about ½ inch in diameter and each contains a single large flattened seed. Fruits turn bright red at maturity and are retained on the plant in pendant clusters into winter and early spring if not taken by the birds. The fruits can be used to make jelly. The three-lobed leaves are dark green during the growing season and will turn a bright red in the fall if the plant is growing in a sunny location. Zones 3 and 4.

Picture of a Baileys compact American cranberry bush

ALFREDO AMERICAN CRANBERRY BUSH (Viburnum trilobum 'Alfredo'), 5-6 ft. This selection is denser than the species and is slightly broader. The summer foliage is a good green, turning red in the fall. Zones 3 and 4.

BAILEYS COMPACT AMERICAN CRANBERRY BUSH (Viburnum trilobum 'Baileys Compact'), 3-5 ft., is a selection made in Minnesota nurseries because of its compact growth habit. Unlike many compact selections of high bush cranberries, this selection is fruitful. This selection is dense and compact to the ground. It turns a bright red in the fall. This plant is useful for foundation plantings and shrub borders. Zones 3 and 4.

European Cranberry Bush (Viburnum opulus), 8-10 ft., has flowers that bloom in large flat-topped clusters in early June. Fruits turn red at maturity and usually remain on the plant until the following spring. They are not normally taken by birds until after they have frozen and thawed several times and if other food is scarce. This species appears to be the most susceptible to aphid injury, which causes the leaves at the tips of the branches to curl under, with the aphids on the underside. Zones 3 and 4.

COMPACT EUROPEAN CRANBERRY BUSH (Viburnum opulus 'Compactum'), 5 ft., is a dense, compact selection. It does not fruit and has little fall color. The summer foliage is a deep green. Zones 3 and 4.

DWARF EUROPEAN CRANBERRY BUSH (Viburnum opulus 'Nanum'), 2 ft., is very dense and so widespreading that it can become 5 feet in diameter. It seldom flowers and consequently usually produces no fruits. It has little or no fall color. Summer foliage is a dark green. This plant is useful where a low mass of dark green is needed. Zones 3 and 4.

SNOWBALL EUROPEAN CRANBERRY BUSH (Viburnum opulus 'Roseum'), 13 ft., produces round clusters of sterile white flowers that make a spectacular show when in bloom. Foliage is dark green and is especially susceptible to aphids, which may disfigure it. It has little or no fall color and produces no fruit. Zones 3 and 4.

Sargent's Cranberry Bush (Viburnum sargentii), 10 ft., is somewhat similar to the European cranberry, but the flowers are larger. Aphids have not been a problem on this plant in University of Minnesota Landscape Arboretum trials. Zones 3 and 4.

 

CURRANT

Although there are many native currants in Minnesota, those used as ornamentals are introduced species. Some fruiting currants and gooseberries are grown for their abundance of edible fruit. These are normally not satisfactory as ornamentals because they are susceptible to leaf spot diseases that often cause them to defoliate in midsummer unless chemical controls are applied.

Alpine Currant (Ribes alpinum), 3 ft., is a shade-tolerant shrub that has been used extensively in landscape plantings in Minnesota for many years. One of its major uses is for clipped, formal hedges. It is usually propagated from nonfruiting plants that are resistant to white pine blister rust. The foliage is dark green and with fine branches. It is susceptible to leaf spot disease that can defoliate plants in late summer. Nurseries have been making selections that are resistant to leaf spot disease. Annual defoliation of alpine currants can be prevented by spraying with a fungicide in midsummer. Zones 3 and 4.

Clove Currant (Ribes odoratum), 5-7 ft., is a shrub that is planted for its abundant yellow flowers that bloom in May. They have a spicy fragrance. Bloom lasts about one week. The foliage is a dark green. Zones 3 and 4.

 

DEUTZIA

Deutzia is a shrub commonly used for landscapes in areas with milder climates than Minnesota's. Its use in Minnesota is limited to one species and a selection of that species. Those with pink flowers are not adapted to this area. Deutzia is useful for foundation planting or as part of a shrub border.

Lemoine Deutzia (Deutzia x lemoinei), 7 ft., is a hybrid that has clusters of small nonfragrant, pure white flowers in late May and early June. It does best when grown in full sun. Tip kill due to winter injury is a common occurrence and branch dieback will occur following severe winters. It is an attractive flowering shrub that is useful to those willing to prune out parts injured by the winter. It makes a quick recovery from winter injury, but blooms only on growth produced during the previous growing season. Adapted to the southern part of zone 4.

COMPACT LEMOINE DEUTZIA (Deutzia x lemoinei 'Compacta'), 5 ft., is a shrub that is denser and smaller than the Lemoine deutzia. Hardiness is similar to the Lemoine deutzia. Adapted to the southern half of zone 4.

Picture of a Compact Lemoine deutzia  

DOGWOOD

Dogwoods are common as both planted and native shrubs. One native species, the pagoda dogwood, can be treelike, but the showy flowering tree dogwoods of the east are not hardy in Minnesota. Dogwoods grow well in full sun or partial shade. They grow well on ordinary soils and most are tolerant of moist sites. Most grow fast. Those with colored stems are more attractive if one-third of the old stems are removed each spring before growth starts.

Gray Dogwood (Cornus racemosa), 8 ft., has small white flowers that appear in mid-June in small, flat-topped clusters. These are followed by white berries on red stems. The fruits are readily eaten by birds but the red stems persist even after the leaves drop. Foliage takes on a purplish color in fall. Stems are gray and twiggy. This native shrub spreads by underground roots, making it useful for a tall bank cover or wildlife plantings. It is an excellent shrub for planting at the edge of woods. Zones 3 and 4.

Picture of a Gray dogwood

Pagoda Dogwood (Cornus alternifolia), 15 ft., is a large native shrub or small tree with horizontally spreading branches. Unlike other dogwoods, the leaf and branching arrangement is alternate rather than opposite. The small, creamy white flowers bloom in dense clusters in June. Fruits are dark blue. The pagoda dogwood appears to grow well on moist and semi-shady sites, although it can tolerate more sunlight and less moisture. Zones 3 and 4.

Red-twig or Red-Osier Dogwood (Cornus sericea), 10 ft., is a broad native shrub with spreading suckers that come up near the base of the plant or where branches touch the ground and take root. White flowers appear in June and are followed by white berries. The stems are bright red during the winter and early spring, but during the rest of the year they lose some of their brightness. Zones 3 and 4.

ISANTI RED-TWIG DOGWOOD (Cornus sericea 'Isanti'), 6 ft., is a slow-growing compact selection of the native red-twig dogwood that was made and named by the University of Minnesota. It is widely grown in Minnesota nurseries. It is susceptible to the same leaf spots as the species, but this is normally not a serious problem. The stem color in late winter is not as bright as on some dogwoods. Zones 3 and 4.

YELLOW-TWIG DOGWOOD (Cornus sericea 'Flaviramea'), 10 ft., is similar to the red-twig dogwood but has a yellow twig color. It has not been as vigorous as the red-twig dogwood. Zones 3 and 4.

Siberian Dogwood (Cornus alba sibirica), 5-7 ft., has cream-colored fiat-topped clusters of flowers that appear in early June, followed by berries that turn blue at maturity in July. The young stems turn a coral red in late winter. This is a fast-growing dogwood although the following selections with variegated leaves (green and white or yellow and white) are much slower growing. These variegated selections normally do best where they are protected from the intense heat of the midday sun. The following variegated selections are sometimes offered for sale in Minnesota: Argenteomarginata, with green leaves edged with white; Gouchaultii, which has leaves that are variegated with yellowish-white; and Spaethii, which has leaves broadly edged with yellow. These are all hardy in zones 3 and 4.

Variegated Dogwood (see Siberian Dogwood).
Yellow-twig Dogwood (see Red-twig Dogwood).

 

ELDERBERRY

Elderberry shrubs grow so vigorously that they are almost weedy. They are adapted to a wide range of soils, but grow fastest on a moist fertile soil. Although shade tolerant, the quantity of bloom and fruit is decreased in the shade. Two species of elderberries are native to Minnesota.

American Elder (Sambucus canadensis), 8 ft., is a coarse native shrub with white flowers in flat-topped clusters that bloom in late June. These are followed by small black berries in late summer, ripening over a long time. The fruits are used for pies and for making elderberry wine. They are also readily eaten by birds. American elder can be planted as a background shrub and used in wildlife plantings. The selection Aurea has golden leaves and bright red fruits. Zones 3 and 4.

European Red Elder (Sambucus racemosa), 8-10 ft., is a shrub grown in borders. It is tolerant of semi-shade. The foliage is dark green and the fruit is red. This shrub and selections from this species are susceptible to cane borers, which cause whole branches to wilt and turn brown. A plant with several infected branches is unsightly. Zones 3 and 4.

REDMAN ELDER (Sambucus racemosa 'Redman'), 8 ft., is a cutleaf selection that forms a compact plant with red fruits. Hardy in zones 3 and 4.

SUTHERLAND GOLDEN ELDER (Sambucus racemosa 'Sutherland Golden'), 12 ft., is the brightest yellow selection of elderberry species evaluated at the arboretum. It is a vigorous grower, but is susceptible to the cane borer. Hardy in zones 3 and 4.

Scarlet Elder (Sambucus pubens), 8 ft., is a native woodland shrub that is the first to come into leaf in the spring. It is often found at the edges of woods. It has pyramidal clusters of creamy white flowers that open in early May. These are followed in July by scarlet red inedible berries. This shrub is of questionable value in foundation or border plantings, but is good for naturalizing in shady areas. Zones 3 and 4.

 

EUONYMUS (see also BURNING BUSH)

This plant has several common names including Burning Bush and Wahoo, which have separate listings in this publication.

This group varies in hardiness. The flowers are very small, but the plant is grown primarily for its abundance of showy fruit. A few species produce little fruit, or the fruit is not conspicuous, but they are grown for their attractive fall color or other characteristics.

Euonymus tolerates a wide variety of soil situations and is tolerant of some shade. Fruiting and fall color are normally better where the plants receive abundant light.

European Euonymus (Euonymus europaea), 8 ft., is a shrub grown primarily for its showy fruits. In late summer, fruits turn a rose-red and remain attractive until late fall at which time they become tan in color. Summer foliage is a dark green, but there is little color change in the fall. This plant is sometimes pruned to a single trunk and grown as a small tree, 10-13 feet tall. This euonymus creates a spectacular show in the fall. Hardy in zone 4, but often with some twig dieback; trial in zone 3.

ALDENHAM EUONYMUS (Euonymus europaea 'Aldenhamensis'), 10 ft., tends to be more compact and fruitful than the species. It sometimes is injured in winter in the southern half of zone 4.

Turkestan or Dwarf Euonymus (Euonymus nanus turkestanica), 3 ft., is a fine-textured upright shrub with narrow leaves, but there are some forms of this species that tend to be low and spreading. The leaves are dark green in the growing season and turn a purple-green during the winter. The pendant fruits are about ½ inch in diameter and are pink, with an orange seed. They ripen in August. Hardy in zones 3 and 4.

 

FALSE SPIREA

This plant has been planted in Minnesota for many years. It is normally grown in shady areas, although adapted to full sun. It spreads by underground stems, producing a thicket effect. This makes this plant useful for a tall bank cover on north-facing slopes. The compound leaves give the plant a rather fine texture. The pointed flower clusters are a creamy white. There are several species adapted to Minnesota, but the one described is the only one that is occasionally available in Minnesota.

Ural False Spirea (Sorbaria sorbifolia), 5 ft., has flowers that appear in late June or early July. The brown seed clusters are not especially attractive and are sometimes removed. Zones 3 and 4.

 

FLOWERING ALMOND

Flowering Almond (Prunus glandulosa), 4 ft., flowers in early May. The flowers are white to pink and single to double. The cultivars of this species are more desirable than the species, such as Alboplena, which has double white flowers, and Sinensis, which has double pink flowers. Zone 4.

 

FORSYTHIA

Forsythia is a favorite spring flowering shrub in many areas with milder climates than Minnesota's. Where this shrub is fully hardy, it is covered with bright yellow flowers in the spring before it comes into leaf. In Minnesota the flower buds of most species and selections are killed by the winter; some suffer dieback of woody parts as well, Forsythia grow best in full sun on a well-drained soil.

Border Forsythia (Forsythia intermedia), 8-10 ft., is a large, spreading shrub with arching branches. This species and its many cultivars are very showy when in bloom but unfortunately we seldom see good bloom in Minnesota. The flower buds are killed at temperatures lower than about -15°F (-26°C). This plant is not recommended except in very sheltered locations or unless they receive some winter protection. Trial in the southern part of zone 4.

Early Forsythia (Forsythia ovata), 6-8 ft., is the hardiest and the earliest of the forsythias. The flowers are smaller and lighter yellow in color than those of some forsythias, but are still very attractive. The plant is also more upright and the branches are stiffer than most. Bloom can be expected in the Twin Cities area about three years out of five if planted in protected sites. Zone 4.

HIGH BUSH CRANBERRY (see CRANBERRY BUSH)

 

HONEYSUCKLE

Honeysuckle is a common name applied to a number of woody and herbaceous plants. Here it applies to the genus Lonicera. This group is made up of fast-growing shrubs that are variable in size. They are best grown in full sun, but are tolerant of light shade, although they become sparse and leggy when grown in the shade. They are tolerant of most soil conditions except for poorly drained soils. Most are quite free of insect and disease problems. Many produce an abundance of berries that are inedible, except by birds. Fruit color is variable depending on the species. A few produce no fruit. This group has some selections that are adapted to foundation and border plantings and for shelterbelts and wildlife plantings.

Amur Honeysuckle (Lonicera maackii), 10 ft., is a large shrub with horizontally spreading branches. The white to cream-colored flowers bloom in early June. The red fruits are borne in flat-topped clusters in late fall. This plant is useful as a background shrub and in wildlife plantings. Zones 3 and 4.

Clavey's Dwarf Honeysuckle (Lonicera x xylosteoides 'Clavey's Dwarf'), 5 ft., is a broad, dense plant that is often used for hedging. Leaves are a medium green. Spider mites are sometimes a problem. Zones 3 and 4.

Emerald Mound Honeysuckle (Lonicera xylosteum 'Emerald Mound'), 3 ft., tends to be more horizontal than upright. This habit allows the plants growing together to create a composite mass useful in foundation plantings or ground covers. The plant has a dark green color and does not fruit. Zones 3 and 4.

Picture of an Emerald Mound honeysuckle

Hedge King Honeysuckle (Lonicera x xylosteoides 'Hedge King'), 5 ft. This is reported to have an upright growth habit. It has yellow flowers followed by fruits that turn red at maturity in the fall. Adapted to zone 4; trial in zone 3.

Tatarian Honeysuckle (Lonicera tatarica), 10 ft. This large shrub is widely planted in shelterbelts, shrub borders, and wildlife plantings. It is sometimes subject to breakage by snow. Flower color varies from white to light red. Fruit color varies from yellow to red. Zones 3 and 4.

Zabel's Honeysuckle (Lonicera x korolkowii 'Zabeli'), 8 ft., is a vigorously growing honeysuckle with dark green leaves. The abundant flowers open a rosy red and become pink as they age. These are followed by many berries that turn red at maturity. The plant itself is denser than the more commonly planted Tatarian honeysuckle, making it a better landscape plant. Zones 3 and 4.

 

HOPTREE

Common Hoptree (Ptelea trifoliata), 12 ft., is a large shrub or a small tree with trifoliate leaves resembling poison ivy. The inconspicuous flowers are followed by clusters of flattened fruits that are winged on each side. Hardy in zone 4; trial in zone 3.

 

HYDRANGEA

Hydrangeas are one of the few deciduous shrubs that normally grow better in semi-shade than in full sun. They are also tolerant of full shade, and will produce bloom. Most hydrangeas grown in Minnesota normally have flowers that are green when they first appear and turn white. One species has a pinkish tinge to the flowers. Those with bright blue and pink flowers have not been hardy. Hydrangeas grow best on a fertile, moist soil, but the soil must have drainage. The large leaves are dark green.

Annabelle Hydrangea (Hydrangea aborescens 'Annabelle'), 3 ft., is one of the showiest hydrangeas that can be grown in Minnesota. It has rounded flower clusters up to one foot in diameter. The flowers are larger and whiter than the older Hills of Snow hydrangea described below. The stems of this plant normally are killed partway back during the winter. It performs best when each stem is cut to ½ inch above the first pair of buds above the ground. This is normally done in early spring, which allows the dried flower clusters to add interest to the winter landscape. This plant is useful in foundation plantings in shady areas. Zones 3 and 4.

Picture of an Annabelle hydrangea

Hills of Snow Hydrangea (Hydrangea arborescens 'Grandiflora'), 3 ft., has greenish white flower clusters up to 8 inches in diameter. At present the cultivar Annabelle is planted in preference to this one. Spring pruning should be the same as prescribed for Annabelle. Zones 3 and 4.

Peegee Hydrangea (Hydrangea paniculata 'Grandiflora'), 8 ft. This plant is often grown with a single stem, giving the plant a somewhat treelike appearance. Otherwise it often grows with two or three stems. This hydrangea has large pointed clusters. When they open in August they are white but they take on a pink or purplish color as they age. During the fall and winter they turn brown, but do add winter interest to the landscape. By removing some of the side or lateral branches, fewer flower clusters are produced but those produced will be much larger. Thinning of the lateral branches is the only pruning required of this hydrangea. This shrub is used for shrub border plantings. Some are used as small, specimen lawn trees. Hardy in zone 4; trial in zone 3.

 

JUNEBERRY

Juneberry is but one of the many common names used for the genus Amelanchier. Other names include: saskatoon, shadblow, and serviceberry.

This is a diverse group that ranges in size from shrubs as low as 3 feet to medium trees reaching 30 feet in height. Juneberries do best in full sun, but will grow in partial shade. Fewer flowers and fruits will be produced in the shade. Juneberries require a well-drained soil. The leaves have a silvery appearance as they emerge. All Juneberries have white flowers that are followed by fruits that mature in July. The green fruits first turn red and then blue-black at maturity. The fruit size is dependent on the species or selection. Fruits are edible, but quite bland and normally taken by birds. The foliage normally turns a bright red in the fall if grown in a sunny location. There is considerable confusion over the identification of specific species of juneberries in the nursery trade.

Regent Juneberry (Amelanchier 'Regent'), 7-10 ft., is a seed-propagated selection that has abnormally large fruits. It is commonly available in the nursery trade. Zones 3 and 4.

 

LEATHERWOOD

Leatherwood (Dirca palustris), 6 ft., is a native shrub that grows best on a fertile, moist soil. It grows in full sunlight but does as well in partial shade, providing it does not have severe root competition for moisture and nutrients. When grown in full sunlight it becomes quite dense. It often grows with a single stem, but normally not more than two or three. It bears small, pale yellow flowers prior to coming to leaf in early spring. Leaves are a medium green and turn a clear yellow in the fall. It is useful for foundation plantings or informal hedges. It is not commonly available in the nursery trade. Zones 3 and 4.

Picture of a Leatherwood  

LILAC

Lilacs are a diverse and useful group of flowering shrubs adapted to growing under Minnesota conditions. They persist indefinitely as attractive plants in the landscape. Lilacs require full sun to produce the abundance of bloom for which the group is known. They are tolerant of a wide range in soil fertility but are intolerant of poorly drained soils.

Spent blooms are often removed, but it is doubtful if this increases the next year's bloom significantly. The old blooms are unattractive, but the seed pods add some winter interest. It might prove beneficial to remove spent flowers from young, recently transplanted lilacs, but once they reach a size making it difficult to remove the blooms, it isn't practical.

Chinese Lilac (Syringa x chinensis), 10 ft. This lilac is often incorrectly called the Persian lilac or rothomagensis lilac. It is the result of a cross of the cutleaf lilac and the common lilac. It is a compact nonsuckering lilac that is useful for informal hedges, in the shrub border, or as a snow catch in shelterbelts. The fragrant lavender and purple flowers are smaller than the common lilac, but are borne in large clusters. Chinese lilac is fast growing and requires little pruning. The dark green leaves are much smaller than those of the common lilac. Zones 3 and 4.

Common Lilac or French Hybrid Lilac (Syringa vulgaris), 12-15 ft., are the names often applied to this group of hybrids. Many of the early selections were made by French plantsmen. This group has the showiest flowers of any group of lilac hybrids. Because of the influences of crosses with other species, the beginning of bloom varies by about 10 days. By selecting some of the early hybrids the bloom period can be extended, although the early blooming hybrids tend to have somewhat smaller flower clusters.

These lilacs are propagated either by budding (a form of grafting) or, preferably, from cuttings. French hybrid lilacs recover fastest from transplanting if they are moved with a ball of soil. If they are moved bare root it often takes several years before they grow normally and bloom.

Some selections have a tendency to produce many suckers from the base of the plant. To prevent overcrowding, remove most of the suckers, leaving six to eight suckers for future growth; one-third of the older stems can be removed to keep the plants perpetually young.

Another alternative in handling large overgrown lilacs is to remove the branches and suckers to train them as a small tree that often has an almost Oriental appearance.

All the lilacs in this group are pleasantly fragrant. Some have single flowers, others double.

There are several hundred selections of lilacs in this group. The Minnesota Landscape Arboretum has nearly one hundred in the lilac collection. Those with an interest in this group are encouraged to visit the collection, which is often in bloom during the third week of May. This group of lilacs is hardy in zones 3 and P4.

Following are some selections that are available at local nurseries:

CHARLES JOLY LILAC (Syringa vulgaris 'Charles Joly'), has double, deep purple, fragrant flowers. It is a heavy bloomer.

CHARLES TENTH LILAC (Syringa vulgaris 'Charles Tenth'), has single, deep lavender flowers and is a heavy bloomer.

CHARM LILAC (Syringa vulgaris 'Charm'). Flowers are single, bluish lavender, and fragrant. It is a heavy bloomer.

DE MIRIBEL LILAC (Syringa vulgaris 'De Miribel'), has single, deep lavender, fragrant flowers and is a heavy bloomer.

EDITH CAVELL LILAC (Syringa vulgaris 'Edith Cavell'). Its single, white, fragrant clusters could be better formed. It is an abundant bloomer.

FIRMAMENT LILAC (Syringa vulgaris 'Firmament'), has single, good blue, fragrant flowers and a medium to abundant bloom.

KATHERINE HAVEMEYER LILAC (Syringa vulgaris 'Katherine Havemeyer'), has double, lavender, fragrant, large clusters and a medium quantity of bloom.

LUDWIG SPAETH LILAC (Syringa vulgaris 'Ludwig Spaeth'), has single, deep red-purple flowers. It is a good bloomer.

MADAME LEMOINE LILAC (Syringa vulgaris 'Madame Lemoine'), has double, white blooms.

MICHEL BUCHNER LILAC (Syringa vulgaris 'Michel Buchner'), has double, lavender and lavender-blue flowers. It is a good bloomer.

MISS ELLEN WILLMOTT LILAC (Syringa vulgaris 'Miss Ellen Willmott'), has double, white flowers.

MONTAIGNE LILAC (Syringa vulgaris 'Montaigne'), has double, pale lavender-blue, fragrant flowers. It is a good bloomer. Young plants at the arboretum had a tendency to be somewhat leggy.

MRS. EDWARD HARDING LILAC (Syringa vulgaris 'Mrs. Edward Harding'), has double, medium purple, fragrant flowers. The quantity of bloom varies from medium to abundant.

MRS. W. E. MARSHALL LILAC (Syringa vulgaris 'Mrs. W. E. Marshall'), is a good bloomer with single, deep purple, fragrant flowers.

NIGHT LILAC (Syringa vulgaris 'Night'). This lilac has single, dark red-maroon flowers. It has a tendency to bloom heavily every other year, but does bloom each year.

PAUL THIRION LILAC (Syringa vulgaris 'Paul Thirion'), has double, deep rosy red-wine to lavender-purple flowers. It blooms heavily every other year.

PRESIDENT GREVY LILAC (Syringa vulgaris 'President Grevy'), has double, lavender-blue flowers. It is a heavy bloomer.

PRESIDENT LINCOLN LILAC (Syringa vulgaris 'President Lincoln'), has single, blue flowers with only a lavender tint. It is a heavy bloomer, but the clusters are small.

VESTALE LILAC (Syringa vulgaris 'Vestale'), is a good bloomer, with single, white flowers.

Late Lilac (Syringa villosa), 10 ft., is an upright shrub with dense, dark green foliage. The flowers are usually pale purple, but are sometimes white. Flowers open after the common lilac has finished bloom. Hardy in zones 3 and 4.

Meyer Lilac (Syringa meyeri), 4 ft. This lilac has been listed under a number of names over the past few years such as Syringa palibiniana and Korean lilac. This plant blooms 10 to 14 days later than the common lilac. The abundant, fragrant, violet-purple flowers are small and occur in small clusters. The plant is compact and has small, dark green, rounded leaves. It produces some suckers. This lilac is sometimes grafted on a standard, giving it a trunk and a miniature treelike appearance. Zones 3 and 4.

Miss Kim Lilac (Syringa velutina 'Miss Kim'), 8 ft., is a compact plant with foliage to the ground. The foliage is dark green, occasionally taking on a reddish purple fall color. The pale lavender, fragrant flowers bloom after the common lilac has finished blooming. The flower clusters are rather small but abundant. This is an attractive plant for foundation plantings and shrub borders. Zones 3 and 4.

Picture of a Miss Kim lilac

Prestonian Hybrid Lilac (Syringa x prestoniae), 10-12 ft. These are late blooming lilacs resulting from a cross of Syringa reflexa x S. villosa. They tend to become large plants. Some have leaves that are rather coarse and that have a rugged appearance by late summer. This group produces few suckers.

DONALD WYMAN LILAC (Syringa x prestoniae 'Donald Wyman'), 13 ft., is a heavy bloomer with single, clear purple blooms opening over a long period of time. Leaves are dark green, smaller than type, and remain attractive till the end of the growing season. Zones 3 and 4.

JAMES MACFARLANE LILAC (Syringa x prestoniae 'James MacFarlane'), 13 ft., is a good bloomer with single, clear pink flowers. The large, medium green leaves can become unattractive by the end of the growing season. Zones 3 and 4.

NOCTURNE LILAC (Syringa x prestoniae 'Nocturne'), 13 ft., is a sparse bloomer with single, light bluish purple flowers and coarse foliage. Zones 3 and 4.

Royalty Lilac (Syringa 'Royalty'), 13 ft., is a hybrid late-blooming lilac with single, fragrant, lavender flowers. The foliage is somewhat coarse. Zones 3 and 4.

 

MOCK ORANGE

This name is probably derived from the fragrant white flowers resembling orange flowers that some species and cultivars of mock oranges have. Some mock oranges are without fragrance. Flowers are single, semi-double, or double and they vary in size. The bloom period is quite short, normally not more than 7 to 10 days. This is probably one reason why there are only a few kinds of mock oranges in the nursery trade although there are many species and cultivars. The summer foliage is dark green and quite free of pest and disease problems. There is no color change in the fall. Some of the older mock oranges have a tendency to become large shrubs and quite leggy in appearance. It is possible that most mock oranges will suffer from occasional tip kill in zone 4 and quite often in zone 3.

Bouquet Blanc Mock Orange (Philadelphus 'Bouquet Blanc'), 4 ft., has fragrant, single flowers 1 inch in diameter. The plant has a moundlike habit of growth. Adapted to zone 4; trial in zone 3.

Galahad Mock Orange (Philadelphus 'Galahad'), 5-7 ft., has small glossy leaves and fragrant medium-size flowers. Adapted to zone 4; trial in zone 3.

Golden Mock Orange (Philadelphus coronarius 'Aureus'), 5 ft., is grown primarily for its greenish yellow foliage. It sometimes exhibits leaf scorch if planted on the south side of white walls. The flowers are single, white, and very fragrant. Zone 4.

Lemoine Mock Orange (Philadelphus x lemoinei), 5-7 ft. Flowers are single, fragrant, and 1 1/3 inches in diameter. Adapted to zone 4; trial in zone 3.

Miniature Snowflake Mock Orange (Philadelphus 'Miniature Snowflake'), 3 ft., is a double, fragrant mock orange that produces a dense bush. Plants in trials at the arboretum have shown severe dieback.

Minnesota Snowflake Mock Orange (Philadelphus 'Minnesota Snowflake'), 7-8 ft., has a double, fragrant flower up to 2 inches in diameter. It is subject to annual dieback in both zones 3 and 4.

Virginal Mock Orange (Philadelphus x virginalis), 10-13 ft., has a large (two inches) semi-double fragrant flower. This mock orange has a tendency to get leggy. Adapted to zone 4; tip kill can be expected if planted in zone 3.

GLACIER MOCK ORANGE (Philadelphus 'Glacier'), 7 ft., has double, fragrant flowers one inch in diameter. Adapted to zone 4; trial in zone 3.

 

NANKING CHERRY

Nanking Cherry (Prunus tomentosa), 10 ft., is often a shrub with a treelike trunk at the ground. Although the plant itself is hardy, the flower buds are often killed during the winter. When they do bloom, they often entirely cover the plant. The flowers are followed by fruits ½ inch in diameter that are either white or scarlet red at maturity. They are eaten by birds and are also useful for jellies. Remove or thin some of the branchlets to encourage active growth and development of fruit. This shrub is useful in the shrub border. Hardy in zone 4; trial in zone 3.

 

NANNYBERRY

Nannyberry (Viburnum lentago), 15 ft., is a common woodland native in many areas of Minnesota. It is also used as a shrub for shrub borders and foundation plantings. Occasionally one will find native specimens that are treelike. This plant has glossy green leaves. It blooms in late May with clusters of ivory-white flowers. The green, oval fruits turn black at maturity. Each fruit contains a single flat seed. The fruits are retained on the plant into the winter or until taken by birds. Plants that are grown in shady areas have little or no fall color, whereas plants grown in a sunny area often take on a good red or reddish purple color. Nannyberry will grow on moist sites, but grows well on ordinary soils. It produces some suckers. Zones 3 and 4.

Picture of a Nannyberry  

NINEBARK

This is a relatively small genus with limited usefulness for landscape purposes. It has several faults. One is that many species of ninebark are fast growing and can become too large for their space in a short time. Despite the fact that Minnesota has a native ninebark, all species can occasionally suffer dieback in winter or be broken by snow. The flowers, which have somewhat of a grayish appearance, are not especially showy. The red-brown seed pods borne in clusters are more showy than the flowers. The foliage has a dark green color.

Dwarf Ninebark (Physocarpus opulifolius 'Nanus'), 3-5 ft., is a dense, dark green arching shrub that is useful in foundation plantings or clipped hedges. Hardy in zone 4; trial in zone 3.

Golden Ninebark (Physocarpus opulifolius 'Luteus'), 7-10 ft., has leaves that are yellow when they appear in the spring. As the leaves age they become more green. This shrub has an arching growth habit. It is useful in the back of a shrub border. Zones 3 and 4.

PEASHRUB (see CARAGANA)

 

POTENTILLA

In some areas potentilla is more commonly called bush cinquefoil. Despite the fact that this shrub is native to Minnesota, all of the selections are from potentilla from other areas. Potentilla does best when grown in full sun on upland soils, although it is found in the wild on some moist sites.

This shrub has several flushes of bloom throughout the growing season. The main flush of bloom occurs in June. The native species has yellow flowers, but selections have been made with pale yellow, bright yellow, orange, red-orange, and white flowers. Selections that have been made for their orange and red-orange flowers tend to bloom yellow under Minnesota conditions. Potentillas bloom best if one third of the oldest stems are removed to the ground each year before growth starts. The growth habit of the plant varies from spreading to upright. Spider mites can cause potentilla foliage to discolor during the warmest part of the summer and should be controlled. All potentillas are hardy in zones 3 and 4.

Coronation Triumph Potentilla (Potentilla fruticosa 'Coronation Triumph'), 3 ft., is a recent Canadian introduction with bright yellow flowers.

Picture of a Coronation Triumph potentilla

Gold Drop Potentilla (Potentilla fruticosa 'Gold Drop,' formerly Potentilla fruticosa 'Farreri'), 2 ft., has medium yellow flowers. The plants are quite compact.

Goldfinger Potentilla (Potentilla fruticosa 'Goldfinger'), 3 ft., is a selection with bright yellow flowers ¾ to 1 inch in diameter. The foliage is a dark green.

Jackman Potentilla (Potentilla fruticosa 'Jackman'), 3-4 ft., has deep yellow flowers 1 inch in diameter.

Katherine Dykes Potentilla (Potentilla fruticosa 'Katherine Dykes'), 2 ft., has medium-size, creamy yellow flowers.

Mount Everest Potentilla (Potentilla fruticosa 'Mount Everest'), 2 ft., is an upright selection with white flowers.

Primrose Beauty Potentilla (Potentilla fruticosa 'Primrose Beauty'), 3 ft., has pale yellow flowers with a broad growth habit. The foliage is silvery gray.

Red Ace Potentilla (Potentilla fruticosa 'Red Ace'), 2 ft., is a spreading plant with apricot-tinged yellow flowers instead of the red flowers it is reported to have in England, where it was selected. This has not been a satisfactory plant in Minnesota.

 

PRIVET

Privets are used extensively in foundation plantings and hedges in areas with milder climates. Even the hardiest privets are subject to winter injury in Minnesota.

Cheyenne Privet (Ligustrum vulgare 'Cheyenne'), 5 ft. This is the hardiest privet, but it will occasionally dieback severely during some winters. It has a dark green, fine foliage. Flowers are small and white. Trial in zone 4.

 

RHODODENDRON (see also AZALEA)

Rhododendrons can be either evergreen or deciduous. Botanically, rhododendrons differ from azaleas by the number of anthers in their flowers. Azaleas have 5 anthers whereas rhododendrons have 10 or more. In general, azaleas and rhododendrons that lose their leaves in the winter come through Minnesota winters better than those that are evergreen.

Like azaleas, they like a moist acid soil, but require soil drainage. Acid peat moss helps acidify the soil as well as increase the moisture-holding capacity of the soil. Plants seem to grow better if they are planted in areas where they are protected from the intense heat of the midday sun during the summer. Most evergreen rhododendrons seem to survive the winter better if they are planted in an area where they are protected from the winter sun. This protection seems to help minimize water loss. Like azaleas, the flower buds of rhododendrons are less hardy than the vegetative parts. This explains why seemingly healthy plants fail to bloom.

Catawba Rhododendron (Rhododendron catawbiense), 3-4 ft., is a dark green broadleaf evergreen with large clusters of lavender flowers. The flower buds are not always fully hardy. This plant becomes broad with age. It is important that this plant be protected from the winter sun. If natural conditions do not provide shade, artificial shade such as burlap should be provided. Trial in the southern half of zone 4.

Korean Rhododendron (Rhododendron mucronulatum), 3-4 ft., is a deciduous rhododendron with abundant medium-size lavender flowers that cover the shrub before it comes into leaf. In the Twin Cities area flowers open in early May and are occasionally injured by spring frosts. There are named selections of this species with clear pink flowers. Unfortunately, these are not available locally. Zones 3 and 4.

PJM Rhododendron (Rhododendron 'PJM'), 3 ft., is an evergreen rhododendron with small leaves. It has clusters of lavender flowers. Hardy in zone 4; trial in zone 3.

Rhodora (Rhododendron canadensis), 3 ft., is a deciduous rhododendron with small lavender flowers. It grows best on a moist site. It loses its leaves in the winter. Zones 3 and 4.

 

ROSE

Roses can be divided into three categories depending on the winter protection required. Space prohibits the listing of the names of many roses adapted to Minnesota's growing conditions. Additional information on the culture, description, and performance of roses is available at county agricultural extension offices. FS-1105 Culture of Garden Roses, deals with the tender types of roses; MR-6591 Roses for the North, deals with the other types.

The first category includes the tender type that require protection to survive. The most practical method of protection is tipping the plant in a trench from about October 15 until April 1. This method is locally referred to as the "Minnesota tip." The roses in this group are: hybrid tea, floribunda, multifloras, miniatures, and climbing roses.

The second group will normally dieback to the ground if they don't receive adequate snow cover. Since snow protection is not dependable, mounding the base of the plants with 2-3 feet of loose marsh hay will normally provide adequate protection. Many of the old-fashioned roses are in this category: gallicas, moss, centifolias, bourbons, albas, hybrid musks, and some shrub roses.

The smallest category includes those roses that survive and bloom without winter protection. They are sometimes subject to twig dieback. These include: rugosa hybrids, some shrub roses, and some species roses.

 

ROSE ACACIA

Rose Acacia (Robinia hispida), 5 ft., is in the pea family. It is a suckering shrub that creates a thicket. The branches of the plant are covered with stiff, black bristles. The large pealike, rosy-lavender flowers are borne in long clusters that appear in June. This plant has potential as a tall bank cover. Some tip dieback can occur after a severe winter. Adapted to zone 4; trial in zone 3.

 

SAND CHERRY

Purple-leaf or Cistena Sand Cherry (Prunus x cistena), 7-8 ft., has leaves that are a deep maroon color throughout the entire growing season. The flowers are pale pink, but not abundant. It needs a sunny location, with well-drained soils. As the shrub ages it has a tendency to become leggy but it can be renewed by pruning the entire plant to within 2 inches of the ground before growth starts in the spring. Adapted to zones 3 and 4.

 

SILVERBERRY

Silverberry (Elaeagnus commutata), 6 ft. Both branches and leaves are covered with silvery scales, giving the entire plant a silvery appearance. The fragrant flowers are silvery on the outside with yellow centers. This plant is native in western Minnesota and is sometimes planted in wildlife plantings or where a contrast in foliage color is desired. It has the objectionable habit of producing many suckers. It sometimes loses its leaves prematurely because of disease. Zones 3 and 4.

 

SMOKEBUSH

This plant is called smokebush because of the smoky appearance of its loose clusters of fine flowers. The flowers are seldom seen in Minnesota because of winter injury.

Common Smokebush (Cotinus coggygria), 15-20 ft. If winter injury does not occur, this plant can become almost treelike. It has produced some bloom in the arboretum plantings. Trial in zone 4.

ROYAL PURPLE SMOKEBUSH (Cotinus coggygria 'Royal Purple'), 10 ft., is grown for its rich, deep maroon foliage. Some winter injury is common with this selection but it is desirable to cut the shrub back to 1 foot from the ground, even if no injury occurs. It makes a quick recovery and is more attractive than if it is not pruned. It must be grown in full sun to achieve the desired deep color. This plant seldom blooms because it is cut back. Adapted to zones 3 and 4 if handled as described above.

SNOWBALL BUSH (see CRANBERRY BUSH, European)

 

SNOWBERRY

Snowberry (Symphoricarpos albus), 3 ft., is a fine-textured shrub with small pink flowers. It is grown primarily for its clusters of white berries borne at the tips of the branches. These are attractive from fall into early winter. This arching shrub is useful for foundation plantings, shrub borders, and bank covers. Zones 3 and 4.

 

SPIREA

There are many spireas but only a few are offered in the nursery trade. Possibly one reason for this is that some spireas have a short period of bloom, sometimes for less than a week. Most spireas have little or no color change in the fall. Spireas grow best in full sunlight and on well-drained soils.

Anthony Waterer Spirea (Spiraea bumalda 'Anthony Waterer'), 2 ft., becoming broad with age. This plant has a bright rosy lavender flower for a couple of months of the summer. Best bloom is achieved if plants are cut to the ground before growth starts in the spring. Zones 3 and 4.

Froebel Spirea (Spiraea bumalda 'Froebelii'), 3 ft., has fiat clusters of bright pink flowers for a long season. Zone 4.

Goldflame Spirea (Spiraea bumalda 'Goldflame'), 3 ft., is new to Minnesota. In the spring, it has a bright golden yellow color that turns to green in the summer. The blooms are a light crimson in color. The fall foliage is often red. Adapted to zone 4; trial in zone 3.

Snowmound Spirea (Spiraea nipponica 'Snowmound'), 3 ft., is covered with white flowers in May. The foliage is dark green. It has had some severe dieback after severe winters. It makes a quick recovery after pruning. Zone 4.

Thunberg Spirea (Spiraea thunbergii), 4 ft., is the earliest spirea to bloom. It has white flowers and fine narrow leaves. Zone 4.

Vanhoutte Spirea (Spiraea x vanhouttei), 4 ft., is an arching shrub that has been planted in Minnesota landscapes for many years. It has an abundance of white bloom, but for only a short period. Zones 3 and 4.

 

SUMAC

This is a diverse group that is useful for extensive plantings. As a group sumacs are fast growing and tolerant of dry, infertile sites. Most have an attractive fall color. Many people are concerned about sumacs being poisonous. Although poison sumac is a native shrub, it is nevertheless uncommon. It occurs on moist sites, mostly in swamps. Poison sumac has hanging clusters of white berries. Sumacs with upright clusters and red fruits are not poisonous.

Cutleaf Sumac (see Staghorn Sumac).

Picture of a Cutleaf staghorn sumac

Fragrant Sumac (Rhus aromatica), 4 ft., grows as a dense mound, making it useful where large mounds are desired in the landscape. Unlike the other sumacs described here, it has three-lobed leaves. The red berrylike fruits are produced in dense clusters at the tip of some branches. There is usually little fall color. Hardy in zone 4; trial in zone 3.

Smooth Sumac (Rhus glabra), to 8 ft., depending on the site and strain. This native shrub is useful for a tall bank cover. It spreads over a large area by root suckers, creating colonies. Some of the colonies will have upright clusters of red fruits, while others will have none. Autumn color is normally a bright red. Zones 3 and 4.

Staghorn Sumac (Rhus typhina), 12 ft., is usually shrublike but if pruned can have a large trunk and become treelike. This native shrub spreads by root suckers. It can be differentiated from the smooth sumac by the dense, velvetlike hairs on the stems. Colonies may produce fruit, depending on their sex. Fall color is an intense red. Zones 3 and 4.

CUTLEAF STAGHORN SUMAC (Rhus typhina 'Laciniata'), 7-8 ft., is similar to the species but has finely cut leaves. The fall color varies from yellow to a red-orange, which is the more common. This selection sometimes suffers winter injury, which ranges from tip dieback to dieback almost to the ground. Even if winter injury is extensive, the plant can be pruned to the ground and it will make a quick recovery. It is often used as a tall bank cover but can be used as a specimen plant. Because of the coarseness of the branching, it takes on an almost sculptured appearance. Zones 3 and 4.

 

TAMARIX

The name tamarix is often confused with the name tamarack, but the plants are distinctly different in size and appearance. Tamarix is a shrub and tamarack is a conifer tree.

Five-stamen Tamarix (Tamarix pentandra), 10 ft. This is the hardiest of the tamarix species. The foliage is made up of very narrow, scalelike leaves. The pink flowers are produced in fluffy clusters in mid-July. Repeat bloom sometimes occurs through the summer. The shrub is inclined to be open and irregular in form. Use as a background shrub in the shrub border. The selection Summer Glow bears an abundance of bright pink flowers for much of the summer. Adapted to zone 4; trial in zone 3.

 

WAHOO

Wahoo (Euonymus atropurpurea), 10-13 ft., is an uncommon native shrub in moist woodlands in the southern part of the state. It is often unnoticed until fall and winter when its bright rosy pink fruits are conspicuous. Unlike the fruit of some of the other euonymus, which lose their color after hard freezes, these hold their color into the winter. This plant is not commonly available. It normally grows as a shrub, but it sometimes has a single stem, giving it a treelike appearance. It is useful as a specimen plant or in the shrub border. Zones 3 and 4.

 

WEIGELA

This shrub goes by a number of common names of which cardinal bush is one. Many have red flowers, but some have white or pink blooms. The shrub is vigorous, with dark green foliage. Its main fault is lack of hardiness. There aren't any in the nursery trade that are reliably hardy under Minnesota conditions. Tip dieback is common after most winters. Dieback to the base often occurs after severe winters. Best bloom is achieved if planted in full sun.

Old-fashioned Weigela (Weigela florida), 6 ft. This species has been quite hardy and normally produces a good bloom of large, rosy pink, bell-shaped flowers in late May. Some dieback can be expected following a severe winter. Trial in zone 4.

VARIEGATED WEIGELA (Weigela florida 'Variegata'), 4 ft., is grown mainly for the yellow variegated leaves. The flowers are clear pale pink. Zone 4.

Weigela Hybrids, 6 ft. A number of cultivars of hybrid origin are in the nursery trade. Vanicek, also known as Newport Red, is the one that is commonly planted. The flowers are bright red and very showy. Dieback is common most winters. Trial in zone 4.

 

WAYFARING BUSH

Wayfaring Bush (Viburnum lantana), 8 ft. This shrub has green leaves that have a silvery appearance because of the many hairs. The flat-top clusters of creamy white flowers appear in mid-May. The fruits are at first green, then turn red, and then black at maturity. This shrub is useful for foundation plantings and shrub borders. Adapted to zone 4; trial in zone 3.

 

WILLOW

There are many species of willows native to the state. Many are shrublike although some are trees. In addition there are willows from other areas that are planted in Minnesota. They often occur on moist soils, but will grow well on other soils. Many lack qualities that make them desirable as ornamentals.

Arctic Willow (Salix purpurpea 'Nana'), 7-8 ft., is finely branched shrub useful for formal and informal hedges. Because of the density of this shrub it is useful in shelterbelts. Adapted to zones 3 and 4, with occasional twig dieback in zone 3 due to winter injury.

Pussy Willow (Salix caprea), 15-20 ft. It is better to keep this plant smaller by cutting it to the ground annually in the spring before growth starts. This will encourage long, unbranched stems from the ground that will bear the large, silvery catkins. Zone 4.

Pussy Willow (Salix discolor), 15 ft., is also better if kept smaller by cutting back to the ground annually each spring before growth starts. This encourages long stems with catkins that are useful for cutting. Zones 3 and 4.

WINGED EUNOYMUS (see BURNING BUSH)

 

WINTERBERRY

Winterberry (Ilex verticillata), 7 ft., is a true holly, but loses its leaves during the winter. It is a native shrub that is often found on moist sites. It should be planted on acid soils and will grow well on upland soils. Plants are of a single sex, so three or more should be planted to assure that some of the plants will fruit. Ideally there should be two to three female plants and one male. The small fruits turn bright red at maturity and persist long after the leaves are gone. The fruits are eaten by many species of birds. Zones 3 and 4.

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