Deciduous trees come in a wide variety of sizes, shapes, forms, colors and textures. Deciduous trees are those that loose their leaves each fall, go dormant for the winter, and leaf out again in spring. They provide us with beauty, shade, and shelter, and are an integral part of our landscapes.
In addition to their beauty, trees benefit us in many ways. They can shade our homes and yards in summer, reducing air conditioning needs. They can reduce cold winter winds, reducing heating costs. They provide food and habitat for birds and wildlife, and help filter dust and pollution from the air. Trees also reduce soil erosion, recycle nutrients, and exchange carbon dioxide for the oxygen we need. Perhaps most important to many people, deciduous trees provide visual structure and canopy, contributing greatly to the aesthetics of our landscape designs.
While many trees are quite tall at maturity, we also utilize a good deal of smaller, ornamental trees in our landscapes. Trees typically have one main trunk, or a "clump" of 2 to 5 stems, or trunks. Some large shrubs can be pruned into tree form; that is, branches are pruned off the lower part of the main "stems" or "trunks" so that there is a canopy formed by the shrub's foliage. Mature trees add beauty and value to our landscapes. They can raise a home's value by 5-10% or more, and generally make our communities more pleasant places to live. However, for a tree to look its best, it must be cared for properly.
Click on any of the following headings and link to chapters that explain selection and maintenance of deciduous trees:
It is very important that tree species are chosen carefully, to avoid major problems later in the tree's life. Consideration should be given in matching the location and species when planting trees, so that the tree has the space and conditions it needs to perform its best.
To begin, analyze the site on which you are considering planting a tree. Because trees are long lived, look at conditions now and what you could anticipate in the future. Does the area receive full sun or a good deal of shade? Is the soil sandy and dry, or heavy and wet? What is the pH of the soil? Does the area get strong winter winds, or is it protected by buildings or other trees? In what hardiness zone is the site? Will the tree be near a busy street and be subjected to pollution or salt damage? How big is the site, and what is the scale of buildings and landscape features around it? You will want to choose a tree species that is adapted to the site conditions.
For more about analyzing the planting site, see Site Survey section in this website.
Also consider the purpose of the tree. Is it to provide shade, wildlife habitat or food, attractive seasonal interest, energy conservation, screening, living snow fence, or some other purpose? You will want to choose a species that fulfills the functions you need.
All of these aspects should be considered before choosing a particular species or cultivar of tree. Perhaps most importantly, you will want to be sure the tree has enough room to reach its full, mature spread without bumping into utility lines, buildings or even other trees. Planting a large tree in a small site or too close to a building will diminish the health and attractiveness of that tree for the life of that tree. Trees should also be spaced far enough apart so that when mature, they will not be crowded and can show their full beauty!
Also be sure there is adequate room for roots to spread out. If tree roots are confined to a small area because of buildings, walks, driveways, roads, etc. (roots will not grow under hard surfaces), the root system will eventually be too small to provide for the size of the tree. The tree will then stop growing, decline, and eventually die.
For more on selecting trees based on site and plant characteristics:
Elements of Design
Tough Trees and Shrubs for Tough Sites
Trees & Shrubs for Clay Soil
Once you have decided on the species or cultivar of tree you wish to plant, there are several options for purchasing your tree. Trees can be purchased bare root, balled and burlapped, or containerized.
Choose trees that have a good central leader and side branches that go horizontally out from the trunk, forming wide crotches. Avoid trees with branches that grow upright from the trunk, forming narrow crotches. Avoid trees with damage to branches or the trunk, or trees that have any visible disease or insect problems.
Avoid narrow branch angles Choose wider branch angles
When planting new trees, big is not necessarily better! In many cases, smaller trees recover from the transplanting shock sooner and reach a good landscape size faster than trees that are transplanted when larger. Newly transplanted trees first spend energy growing a sufficient root system, and usually do not put on much top growth the first or second years following planting.
Planting a bare root tree
Bare root trees are usually available only in early spring. These trees are dug from nurseries in late fall, and all soil is removed from their roots. They are held in climate controlled coolers over winter and sold bare root in spring. If you are planning to plant many trees (five to ten or more), it is a good idea to order your bare root trees from your local nursery ahead of time.
While bare root trees can be very economical, the trees can be highly perishable and it is very important that the roots never be allowed to dry out. They are usually available only for a short time in spring (usually the end of April or beginning of May in the Twin Cities area) so you do not have the flexibility of when to plant the trees that you have with containerized or balled and burlapped trees. Bare root trees typically have a maximum 1 1/2-inch trunk diameter.
How to plant a bare root tree
Source: SULIS http://www.extension.umn.edu/garden/landscaping/implement/planting_trees.html
Planting a container-grown tree
Container-grown trees are sold in a variety of different sized pots. The pots may be plastic, paper maché, or wooden "bushel baskets". In some cases, the tree had been growing in the container since it was a seedling; in others, it was planted in the container as a bare root tree. These trees are available throughout the growing season, and can be held in the containers for quite some time, allowing for more flexibility in planting.
How to plant a container-grown tree
Source: SULIS http://www.extension.umn.edu/garden/landscaping/implement/planting_trees.html
Planting a balled and burlapped tree
Balled and burlapped trees (B&B) are trees that are dug with the soil around the roots (root ball) intact. That root ball is wrapped in burlap and enclosed in a wire basket which is tied around the trunk. Balled and burlapped trees cost more than bare root stock, but they are typically available throughout the growing season. Larger diameter trees are usually sold this way rather than bare root or containerized. The root ball of balled and burlapped trees can dry out very easily, so when choosing a tree, make sure it is well mulched and does not look dry or otherwise stressed, and be sure to keep the root ball moist until you get it planted.
How to plant a B B tree
Source: SULIS http://www.extension.umn.edu/garden/landscaping/implement/planting_trees.html
Sometimes, people own or have access to woods and attempt to transplant small trees out of the woods into their yards. While this is possible in some cases, trees transplanted in this manner have a much lower survival rate. Usually, a much smaller percentage of roots are dug than with nursery-grown trees which are subjected to root pruning to create a compact root ball. Also, these trees suffer severe stress when planted out in the open after having grown up with the shelter of surrounding trees. The trunks are typically thin and overly flexible, causing severe bending in the wind, and the bark is subject to sun scald (damage from winter sun). Finally, trees from the woods usually do not have the form and branch structure desired for attractive landscape trees. If, however, you choose to transplant trees from a woodland, it is best to move only smaller specimens (4-5 feet maximum height) rather than taller trees for a higher success rate.
Whichever type of tree you choose to plant, it is imperative that the tree is planted correctly to get it off to a good start. If planted too deeply, the tree may develop girdling roots--roots that grow upward toward the surface for oxygen, then turn back toward the trunk, eventually strangling the tree. For more about girdling roots, see A Practitioner's Guide to Stem Girdling Roots of Trees.
Young trees should also be staked for support their first year, mulched for trunk protection and moisture moderation, and protected from damaging winter sun and winds. Trunks of young, smooth-barked trees should be wrapped for several winter seasons in the cold Minnesota and Wisconsin climate.
For detailed information on planting bare root, balled and burlapped and containerized trees, see Planting Bare Root, Containerized and Balled and Burlapped Trees and Shrubs.
Planting and Transplanting Trees and Shrubs
Newly planted trees need special care for the first year or two to become well established. No matter how carefully dug, transplanted trees have only a fraction of their original root mass and are less able to take up water and nutrients.
When planting a deciduous tree, limit pruning to removing broken or damaged branches, or branches that are crossing others or growing inward toward the trunk. If there is more than one leader, choose the strongest and straightest one and remove the others. If there are any broken roots, prune those away as well. Always use sharp pruning tools and make good, clean cuts.
If narrow crotches are not eliminated when the tree is small, the tree can split when it gets older, as shown in this picture:
When planting, the soil in the entire root zone should be thoroughly soaked with water. The tree will need regular watering for the first year, and periodic supplemental watering for the next several years, to develop an extensive root system.
Monitor the soil moisture around your newly planted tree. The tree will need at least an inch of water each week. This can be provided by nature, in the form of rain, or by you with supplemental watering. A thorough weekly watering is much better for the tree than light daily waterings. If you have heavy soil, a soaking once a week will be probably sufficient except in the hottest weather. If you have sandy soil, you may need to soak the root zone twice or more each week, depending on the weather and temperatures.
A good rule is to dig down with your finger above the roots. If it is dry an inch down, it is necessary to water. If the soil is still wet from a recent rain or previous watering, delay watering until it dries out some. Overwatering can be just as harmful as under watering. Plant roots need oxygen as well as water. Too much water fills the air pockets between soil particles and creates an anaerobic environment. This can result in root rot and an environment favorable to other pathogens such as fungi and bacteria.
It is not enough to pour a bucket of water around the trunk of the tree. It is important that the outer edges of the root zone be watered to encourage the roots to grow out into the soil. If you water only near the trunk, the roots will stay in that small area and not grow out into the surrounding soil. The tree will then not be anchored and will be more susceptible to tipping and being uprooted in strong winds.
Keeping the newly planted tree mulched with organic mulch, such as shredded wood, will retain moisture and reduce competition for moisture and nutrients from weeds and grasses. This can increase growth of the tree during the first few years dramatically! Keeping grass away from the tender young tree trunk will also help prevent damage from lawn mowers or string trimmers.
Applying organic mulch around the base of trees helps retain moisture, control weeds, moderate soil temperature, and give a nice appearance to the landscape. Most any organic material can be used as mulch, including shredded wood or bark, wood chips, pine needles, cocoa bean hulls, straw, ground corncobs, or any other available organic matter.
To be effective, mulches should be applied so that when settled, it is 3-4 inches deep. However, be sure to pull mulch away from the trunk or stem of the plant. Mulch left against the bark can cause moisture buildup which can rot the bark and cause severe injury to the plant. Avoid the "volcano" of mulch around a tree's trunk, and instead apply a "donut" of mulch. Also, do not use a landscape fabric or plastic when using organic mulches.
It is important to keep mulch away from tree trunks
to avoid retention of moisture against the wood and potential rot.
Inorganic materials often used as mulch, such as landscape rocks, can also be used. However, rock tends to absorb heat during the day and release it at night, which can be stressful for plants. Also, you will need to use a landscape plastic or fabric under the rock to control weeds, which you would not use with an organic mulch.
Newly planted trees can also benefit from fertilization to build a good root system, if planted early in the season. You can put a slow-release fertilizer in the planting hole, or soak the tree with a water soluble liquid starter fertilizer after planting. Putting ordinary granular fertilizer in the planting hole can injure the roots, so be sure to use a slow release fertilizer or fertilize from the top.
However, if planting a tree in late summer, it is best to wait until late fall or early spring to fertilize the tree. Fertilizing in late summer can cause excessive growth which will not harden off in time for winter.
It is best to have a soil test done to know what nutrients are lacking in your soil. However, in the absence of a soil test, newly planted trees can usually get a good start with a balanced fertilizer such as 10-10-10. For information about the basics of fertilizers, see Fertilizer Basics for Trees and Shrubs.
Be sure to provide any necessary winter protection during the first few years of a tree's life. Most young trees have thin bark and are subject to trunk damage from sun scald. Sun scald occurs when the late winter sun, which is getting stronger, warms the bark on the tree and causes some cells in the cambium to become active. When the sun suddenly goes behind a building or sets for the evening and the temperature quickly drops below freezing, those active cells are damaged and die. This results in a big wound (canker) on the tree trunk.
Depending on the severity of the damage, sun scald can kill the tree quickly or cause problems for years to come. Eventually, the damaged area can decay to the point of causing a weak trunk and making the tree a hazard. Symptoms of canker damage include reduced growth on that side of the tree, smaller than normal leaves, and early fall color.
Sunscald can form a large canker on the tree trunk
To prevent sun scald, young tree trunks should be wrapped with a tree wrap, burlap, or some other product that will insulate the trunk from the warm late winter sun. Light colored or white wraps will reflect the sun. Often, brown thin tree wrap is not enough as heat is conducted through to the bark. Tree wraps should be applied in November and removed in spring each year. You can stop wrapping the trunk when the bark begins getting corky and thicker and is able to provide its own protection. Smooth barked trees, such as maple or cherry, are very susceptible to sun scald injury and will need to be wrapped for several years after transplanting.
Trees also face a threat of winter injury due to rodents and other animals feeding on the bark and twigs. This feeding may permanently disfigure the tree, and if damage is severe enough, the tree will die. Thin barked or young trees are most susceptible to damage by animals.
Animal damage to bark of young tree
Protect the tree's trunk from rabbits and mice by placing a ring of 1/4-inch mesh hardware cloth around the trunk. The mesh should be buried 1-2 inches below the soil line to protect against burrowing rodents, and should extend two feet above the expected snow level to protect against rabbits.
If the hardware cloth touches the trunk, it should be removed in spring to allow for trunk growth outward. If the hardware cloth is several inches larger than the diameter of the trunk, it can be left on year round. Plastic spiral tree guards which are available from most nurseries or garden centers, can also protect against wildlife damage on smaller trees. Whatever you use, be sure it is not restricting trunk growth.
There are also repellents available to control animal damage. You can either spray or paint them on the tree trunk and branches. However, repellents often don't last very long and may need to be reapplied after rain or heavy snow.
Deer can cause severe damage to trees. They feed on tender buds of small trees, causing breakage and disfigurement. They also rub their antlers on the trunks during the autumn rutting season, which breaks branches and damages bark. Deer are very difficult to control, and people have come up with some very creative repellents. Wrapping trunks with hardware mesh can protect bark from rutting damage. Hanging repellents from branches may also be somewhat effective. Common repellents include small bags of human hair, blood meal, or bars of soap.
If you live in an area with high wildlife populations, you may try to choose plant species that are not favored by wildlife. For more information about wildlife, see Trees - Protecting from Rodent Damage.
Once trees are established, they usually require less care than a newly planted tree. That is, of course, if the tree is suited for the site and is not under undo stress. Trees that are stressed because their soil, light, or climate conditions are not appropriate will be more susceptible to insect, disease, and dieback problems and will always require more maintenance than trees that are planted in suitable conditions.
Mature, established trees typically require less pruning than young trees do. You will probably only have to prune to eliminate safety hazards or damaged branches, and to improve the appearance of the tree. Pruning is required for:
- Crossing branches that rub on each other, which will damage the bark and attract diseases and insects.
- Branches dead, dying or diseased.
- Water sprouts (young, weak growth that grows straight up off of horizontal branches)
- Sprouts at or near the base of the tree trunk.
- Branches that form with arrow angled crotches, which will be weak and split easily in high winds.
- Branches damaged in storms or by other means.
The best time to prune most trees is during late winter, before plants begin to leaf out in spring. Pruning cuts heal most quickly in spring, and diseases and insects that spread diseases are dormant during winter. Oaks especially should be pruned only during the winter to avoid infection with the oak wilt fungus. NEVER prune oaks between April 15 and September 1.
Spring flowering trees, such as crabapples, will have formed their flower buds during the previous summer. Pruning in winter will remove some of those flower buds, resulting in reduced flowering the following spring. For best flower production, it is best to prune flowering plants just after the flowers fade.
If pruning a diseased tree and to be safe when pruning healthy trees, be sure to disinfect pruning tools between cuts by dipping the tool in a 10% bleach solution between pruning cuts. This will reduce the potential for spreading the disease
The use of wound paint or dressings is not recommended. It may actually interfere with the tree's natural ability to heal a wound. However, if an oak tree is damaged during the summer when oak wilt fungus and the insects that transmit it are active, it is recommended that a dressing be thickly applied to prevent the transmission of the oak wilt fungus.
Pruning some trees, such as maple or birch, in spring will result in "bleeding" or oozing of sap. This oozing may create a unsightly sticky area attractive to insects; however, it does not affect the overall health of the tree.
Large trees can be difficult to prune because of their size. For safety reasons, it is often best to hire a professional arborist to assess and prune large trees. For more on finding a qualified arborist in your area, see Hiring an Arborist.
Storm damaged trees should be pruned to improve their shape and reduce hazards. Again, if a large tree has been damaged, for safety reasons it may be necessary to hire a qualified, certified arborist.
Established trees usually have an extensive root system that is capable of extracting necessary water and nutrients from the soil. However, during extended periods of dry weather, most trees will benefit from supplemental watering. Running the hose at the base of the trunk is usually ineffective, because most of the root system - including the most active roots - grow at or beyond the tree's dripline (the ends of the spreading branches). It is best to put a slow sprinkler on the soil above the root zone and let it run for an extended period of time.
Typical root spread of an established tree
Source: SULIS http://www.extension.umn.edu/garden/landscaping/implement/planting.html
Beware that overwatering can be as detrimental to a tree as under watering. Once the root zone is thoroughly watered, it is typically not necessary to water again for two weeks or more, depending on soil type and weather conditions. Too much water may suffocate tree roots and cause root rot. Turfgrass requires water more often than trees to stay green and healthy. If the tree is planted in a lawn grass area, be sure not to overwater the grass. Irrigation systems should also be calibrated so that trees are not overwatered.
Applying organic mulch around the base of trees helps retain moisture, control weeds, moderate soil temperature, and give a nice appearance to the landscape. Almost any organic material can be used as mulch. Some popular, easily available materials include shredded wood or bark, wood chips, pine needles, cocoa bean hulls, straw, and ground corncobs. If the shrubs are mulched with an organic material, such as wood chips or shredded wood, additional applications of nitrogen fertilizer may be needed. As the mulch decomposes, microorganisms compete for nitrogen which may result in nitrogen deficiencies in the plants..
To be effective, mulches should be applied so that when settled, it is 3-4 inches deep. Be sure to pull mulch away from the trunk or stem of the plant. Mulch left against the bark can cause moisture build-up which may rot the bark and cause severe injury to the plant. Do not create a "volcano" of mulch around the trunk of the tree, but form a "donut". Also, do not use a landscape fabric or plastic when using organic mulches.
It is important to keep mulch away from tree trunks
to avoid retention of moisture against the wood and potential rot.
Inorganic materials often used as mulch, such as landscape rocks, can also be used. However, rock tends to absorb heat during the day and release it at night, which can be stressful for plants. Also, you will need to use a landscape plastic or fabric under the rock to control weeds, which is unnecessary with organic mulches.
For more information:
Mulching the Home Landscape
Most well-established, mature trees do not need a lot of fertilization. If the tree is growing in a lawn which is occasionally fertilized, the tree is probably getting enough nutrients. Trees in woodlands where leaves and other vegetation are left to decay also usually get necessary nutrients. However, trees growing in lawns and landscapes may sometimes benefit from supplemental fertilization. Providing adequate nutrients will help keep a tree vigorous and healthy and more able to defend against diseases and insects.
A soil test from a professional, qualified lab will provide an analysis of existing nutrients in the soil, as well as recommendations for fertilization. For assistance with taking and submitting a soil test, contact your local county University Extension office.
The following signs could indicate that a tree would benefit from fertilization:
- Small or off-colored leaves (especially yellow or purple leaves)
- Sparse foliage
- Dieback on the ends of branches
- Slower than normal growth
To fertilize a mature tree, map out imaginary concentric circles every two feet starting about twice the trunk diameter away from the trunk. The last circle should be just beyond the drip line. On these circles, make holes with a pipe or soil core probe spaced two feet apart and 12-15 inches deep. Fertilizer should be applied into the holes, topping each hole with soil. An alternative is to use a tree root feeder that attaches to a garden hose and deposits dissolved fertilizer below the soil surface in the tree's root zone. If the root zone of a tree is mulched with organic mulch, it is best to spread fertilizer over the mulched area of feeder roots. After fertilizing, it is important to water well, so that the nutrients move into the root zone.
The only way to be certain which nutrients to add is to have a soil test. Generally speaking, soils in Minnesota and Wisconsin do not require phosphorous supplements. Potassium may also be plentiful. However, a commercial fertilizer with a high nitrogen content, such as 12-4-4 or 18-3-4 is usually an appropriate addition to area soils. Follow label instructions for the proper amount of fertilizer to use. If unclear, a good rule of thumb is to apply 1 to 2 pounds of fertilizer per inch of trunk diameter. Flowering trees should be limited to one pound per inch of trunk diameter. The total amount of fertilizer used should be divided evenly between the holes made on the imaginary circles.
The frequency of fertilization will depend on the tree's response and goals for its growth. If fast growth on young trees is desired, it is best to fertilize annually. Older trees or slow-growing trees may need fertilization only every 3-4 years. For information about the basics of fertilizers, see Fertilizer Basics for Trees and Shrubs.
For additional information on fertilization:
Tree Fertilization: Guide for Fertilizing New and Established Trees in the Landscape
Preventing Pollution Problems from Lawn and Garden Fertilizers
Modifying Soil pH
Mature trees usually do not need any special winter protection. Young smooth barked trees should have their trunks wrapped to prevent sunscald. Sunscald occurs on the south or southwest sides of the trunk due to warming of the trunk by the stronger, late winter sun. The cells under the bark become active when warmed but will freeze and become damaged when the sun goes down at night. Wrapping the trunk with plastic, burlap, or some other product will prevent warming of the trunk. Materials should also be light-colored in order to reflect light and warmth instead of absorbing it.
Salt used to melt ice on pavement can damage a tree in two ways. Trees planted within 50-100 feet of highways often suffer from salt spray damage, resulting in bud death and twig dieback. New growth then occurs mainly near the branch bases, creating clusters of twigs called "witches' brooms."
Salt can get into soil in several ways, including being sprayed by traffic, plowed off the road, or by draining with melted snow and ice onto soil surfaces. Salt in the soil can kill roots directly or can prevent them from taking up water, causing drought injury. Often, injury cased by salt exposure does not show up for a year or more. Symptoms including a blue-green cast to the foliage, small leaf size, marginal leaf burn, early fall color and leaf drop, and stunted growth.
The best control for salt damage to trees is to plant trees initially where they will not be exposed to salt, and to use as little deicing salt as possible. While it is impossible to control salt use on public streets, try to not plant trees in areas where melting snow and ice will run off. Finally, in areas where salt will be present, plant species that are tolerant of salt.
The buildup of ice or heavy wet snow may cause damage to trees during winter. Multi-trunk trees especially can split if the weight of the buildup becomes too great. In most cases, freezing rain buildup on branches will not harm the tree. Branches may sag, but are flexible enough to withstand the weight and will bounce back once the ice melts or falls off. If ice build-up is less than 1/8 inch thick, it is best to leave it alone and not risk damaging branches while trying to remove the ice.
In cases of extreme ice buildup where there is a risk of branches breaking because of the weight, it is helpful to carefully remove some of the ice. Use a rake handle or other round stick to gently tap the branches to remove some of the ice. It is not necessary to remove all of the ice, just enough to eliminate the threat of breakage because of the weight of the ice.
Always beware of power lines and other hazards resulting from the ice storm that may be present.
Trees may be injured by rodents and other animals feeding on the bark and twigs. This feeding may permanently disfigure the tree, and if damage is severe enough, the tree will die. Trees with thin bark or young trees are most susceptible to damage by animals.
Protect tree trunks from rabbits and mice by placing a ring of 1/4 mesh hardware cloth around the trunk. The mesh should be buried 1-2 inches below the soil line to protect against burrowing rodents, and should extend two feet above the expected snow level to protect against rabbits.
If the hardware cloth touches the trunk, it should be removed in spring to allow for trunk growth outward. If the hardware cloth is several inches larger than the diameter of the trunk, it can be left on year round. Plastic spiral tree guards which are available from most nurseries or garden centers, can also protect against wildlife damage on smaller trees. Tree guard materials should never restrict trunk growth.
There are also repellents available to control animal damage. You can either spray or paint them on the tree trunk. However, repellents often don't last very long and need to be reapplied after rain or heavy snow.
Deer can cause severe damage to trees. They feed on tender buds of small trees, causing breakage and disfigurement. They also rub their antlers on the trunks during the autumn rutting season, which breaks branches and damages bark. Deer are very difficult to control, and people have come up with some very creative repellents. Wrapping trunks with hardware mesh can protect bark from rutting damage. Hanging repellents from branches may be effective. Common repellents include small bags of human hair, blood meal, or bars of soap. A variety of commercial repellants are also available.
Trees - Protecting from Rodent Damage
Heavy pedestrian or vehicle traffic over the root zone of a tree can cause damage due to soil compaction. Compacted soil prevents oxygen from reaching the tree roots, causing root injury or death. This is especially a problem in areas with heavy clay soils. Compacted soil can be aerated by making a series of holes in the root zone using a core soil auger. The holes can then be filled with sand or peat moss to allow oxygen to reach the root zone. The best solution is to create a landscape design that minimizes traffic in the root zones of trees.
For additional information on tree care:
Protecting Existing Trees During Construction
Flood Stress on Trees
Caring for Your Established Shade Trees
Plant Injury Due to Turfgrass Broadleaf Weed Herbicides
Living Snow Fences
Energy Saving Landscapes