Planting Trees in Minnesota

A casual observer might conclude that most of Minnesota's forested areas are amply covered with trees. However, closer examination would reveal that much of this land is covered with brush. A considerable portion is stocked with either too few trees or an overabundance of low-value tree species, intermingled with abandoned fields.

We are growing more wood than we are harvesting. This will change because as our population grows, the consumption of wood products increases. We will need more trees to supply this demand. Aspen and other low-value hardwoods account for most of the present surplus. However, there is a shortage of high-value species, such as pines and spruces.

The area for growing our wood supply is gradually decreasing. New power lines, roads, home sites, industrial sites, and recreation areas are whittling away our wood-growing areas. In the future we will have to grow trees more efficiently.

Whether you plant trees for the production of Christmas trees or long-term products such as posts, pulpwood, or logs, growing trees increases the value of your land. In some cases, this land is eligible for special tax treatment under the Minnesota Tree Growth Law. This law provides a long-term, constant tax rate based on the value of the annual timber growth.

Sources of Planting Stock

Planting stock for general forestry and wildlife purposes is available at nurseries operated by the Minnesota Division of Forestry, located at Willow River and Badoura.

Tree seedlings are available for afforestation or reforestation, wind-breaks, shelterbelts, erosion control, soil and water conservation, or for food and cover for wildlife. They may not be used to raise fruit for human consumption or be planted for ornamental purposes. They cannot be given away or resold with roots attached (Minnesota Laws 1947, Chapter 94).

Seedling and transplant stock is available at reasonable costs. For current prices, contact your county extension agent, local forester, or Soil Conserva-tion Service office. The different species must be ordered in multiples of 100 and a total of 500 trees is the minimum number that can be ordered.

The Division accepts orders after September 1 for trees that will be delivered the following spring. Orders are accepted on a first-come, first-served basis. Many people fail to get the type and number of trees they want because they submit their orders too late, so place your order as soon as possible after September 1.

The Division also provides a special application form for ordering plant-ing stock. The form can be obtained at county agents' offices, state forestry stations, county Agricultural Stabilization and Conservation Service offices, or by writing to the Division of Forestry, Centennial Building, St. Paul, Minnesota 55155.

The following coniferous species usually are available each year: jack pine, Norway (red) pine, white pine, white spruce, Norway spruce, black spruce, and white cedar. Deciduous species usually available are soft maple, green ash, and black walnut. Shrub species available are caragana, honeysuckle, and ginnala maple. Some years, limited amounts of different species (Colorado blue spruce, balsam fir, Black Hills spruce, etc.) also are available. Coniferous species grown in state nurseries usually are 3-0 stock; i.e., they have grown three years in a seedbed and not in transplant beds. Conifer transplant stock is also available. These plants have grown two years is a seedbed and either one year (2-1 stock) or two years (2-2 stock) in a transplant bed.

Trees can be delivered from the nursery in various ways. They may be shipped by express (collect) or you can pick them up at the nursery. Many counties make provisions for delivery by county truck or custom haulers. Check with your county agent to determine what method is used in your area.

Several commercially operated nurseries in the Upper Great Lakes region supply forest tree seedlings in various sizes and grades. Names and locations of these nurseries can be obtained from county extension offices.

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Choice of Species

The general site and the soil and moisture requirements of each species should be considered carefully. One or more species of conifers usually can be grown in the soil types of Minnesota forest regions. The various deciduous (broad-leaved) species are more demanding in their requirements.

Planting success hinges on selecting a species that is adapted to the site factors of moisture, soil quality, and competition with other vegetation. Other factors that affect planting success are the amount of exposure to wind and sun; the possibility of animal, insect, or disease damage; and the species' ability to endure our severe winter climate.

Figure 1. White pine blister rust hazard zones in Minnesota.

White pine cannot be recommended for planting in some parts of Minnesota because of the virtual certainty of white pine blister rust infection. (figure 1). Ponderosa pine, Norway spruce, and black walnut should be planted only with hardy seed sources.

Matching a tree with its planting site is particularly important when the species is not native. For example, both Scotch pine, introduced from Europe, and ponderosa pine, native in the western United States, may winterkill unless the original seed source is carefully selected.

In general, pines grow better in sandy soils than in fine-textured soils, while the opposite is true of broad-leaved hardwoods. On fine-textured soils with poor drainage, spruce, balsam fir, and northern white cedar are recommended. One of the best ways to check how trees will do on your land is to observe species growing naturally in the same vicinity (see table).

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Site Preparation

Many successful plantations have been established in fields that have had no special preparation prior to planting. Generally, most fields with sandy or sandy loam soil require no preparation. However, fields containing fine- textured soils and a thick sod cover or dense, tall grass should be worked up the year prior to planting. The ground should be plowed, disked, and dragged, which is the type of preparation required for planting any crop. At the minimum, a couple of cross diskings with a heavy brush disk may be sufficient preparation. Applying one of the newer chemical weed killers, either the previous fall or at planting time, should be considered.

Get rid of brush before planting. Tree seedlings that are crowded or shaded by brush have a poor chance of surviving. Chemical brush killers provide one of the best and most economical ways to get rid of brush. Disking or bulldozing heavy brush when the ground is frozen is another quick way to eliminate brush, but any roots left in the ground will resprout. Cutting brush is wasted effort; cut stems send up new sprouts that are twice as numerous and more vigorous than previous stems. However, cutting brush followed by chemical control can be very effective in brush elimination.

In choosing the most desirable spacing, you should consider the tree's growth habits and the purpose for which the tree is planted. For a timber stand, Norway pine should be spaced 6 to 10 feet apart. Christmas tree plantings ordinarily are spaced at six-foot intervals. If they are spaced closer, the lower branches do not have enough room to develop properly.

The following table shows the number of trees per acre at various spacings:

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Care and Handling of Stock

Forest planting stock usually is shipped in bundles of 500 to 1,000 trees. They are packed tightly in wet peat moss or sphagnum moss to keep them from drying out in transit. If you plant within a day or two, it is unnecessary to open the bundle until you start planting. However, it is a good idea to pour some water into the ends of the bundles and store them in a cool, shady place.

Spring is the best time to plant, as soon as the frost is out of the ground. The soil is moist, the climate mild, and trees establish themselves quickly. With a full growing season ahead, they get a good start on competing weeds and brush. Planting forest trees in the fall often is less successful.

Figure 2. Heeling in seedlings to protect roots. Left: Select a shady spot and dig a V-shaped trench in soil that is moist. Right: Open a bundle of trees and spread the roots out evenly along one side of the trench. Left: Stamp down the soil for a firm covering. Right: Water the heeled-in trees each morning. Drench well with water.

When your trees are delivered: (1) Pick them up promptly upon notice of arrival; (2) Give them a good soaking without delay (do not leave trees in the wrapped package more than two or three days, because they may dry out, heat, or mildew); and (3) If you are not going to plant the trees for several days, "heel in" the trees in a trench, preferably in a cool, shady place (figure 2). Make the trench deep enough for the entire root system and part of the lower stem.

Place trees side by side in a single layer in the trench, then thoroughly pack soil around the roots. Water the trees daily. Trees may be left heeled-in for a week or more if you do the job well.

During planting, have plenty of water on hand so tree roots will be moist at all times. Use moss that seedlings were packed in to keep roots moist. Remember: DRY ROOTS MEAN DEAD TREES. Handle each tree carefully to avoid skinning the bark, breaking the tips, or injuring the roots in any way.

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Planting Methods

Figure 3. A mechanical tree planter can increase the planting rate many times over that of hand planting. However, the quality of the planting depends on the skill of the machine operator.

Mechanical tree planters, introduced after World War II, have replaced hand planting in most cases. With a planting machine, you can plant trees at a faster rate, more uniformly, and with less effort (figure 3).

Planting machines are available for loan to private landowners in nearly every county. County extension agents or Soil and Water Conservation Districts have assumed responsibility for scheduling use of this equipment. A nominal fee usually is charged to pay for maintenance and repair costs.

These machines are relatively lightweight (approximately 500 pounds) and ordinarily are used only for open field planting. The landowner must furnish the tractor and labor. A three-person crew is the most efficient-one worker on the tractor, another on the planter, and a third opening bundles and supplying trees.

On long rows (where a minimum of time is spent turning around), if soil conditions are favorable it is possible to plant 1,000 trees an hour. The machines are simple to use and, with a little practice, the operator can become proficient at planting.

Some private operators do custom planting. Their rates vary considerably. County agents and state foresters usually are familiar with the people doing this type of work in their areas.

Tree planting machines cannot be used on all sites. Hand planting must be resorted to on sites where there are stumps, rocks, steep slopes, low areas, and brush or tree cover. A variety of tools can be used to plant a tree: shovel, grub hoe, mattock, or planting bar. Under favorable conditions, a trained worker can hand plant 500 to 800 trees a day.

Figure 4. Placing seedlings at the proper depth. Left: Incorrect. Note how the root is curled up. Curling prevents proper growth. The tree will die. Center: Incorrect. Some roots are exposed to the air. A slight tug will uproot the seedling, Right: Correct. Place the seedling in the hole at the same depth it grew in the nursery. Figure 5. Using a planting bar following furrowing. Left: Plunge the bar into the ground at the angle shown and push it forward to an upright position. Center, left: Place the seedling against the flat side of the planting hole. Center, right: Plunge the bar into the ground 3 inches from the seedling. Right: Push the handle of the bar forward to pack the soil at the top of the roots. Left: To close the hole, plunge the bar into the ground 3 inches from the last hole. Center, left: Work the bar forward, then pull it backward, filling the hole. Center, right: To fill the last hole, tramp in the loose soil with your heel. Right: Stamp down any loose earth around the seedling to prevent air pockets.

It is a good idea to "scalp" off some of the sod where the tree is to be planted. Make certain the hole is deep enough to accommodate the seedling's entire root system (figure 4). Plant the seedlings at the same depth as they grew in the nursery. This can be determined by the "root collar," a slight swelling on the stem that develops in the nursery at the ground line, just above the roots. Pack the soil firmly to eliminate air pockets around the roots. This can be done by stamping your foot alongside the seedling (figure 5).

As a general rule, fertilization is not required. In occasional instances, some symptom of nutrient deficiency might show up, often as foliage discoloration. If this occurs, consult your county agent or soil conservationist.

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Care of Plantations

A plantation of trees is an investment of time, labor, and money. However, it offers the possibility of future financial returns. For this reason, you should protect and care for your plantation as it grows to maturity.

Fires are foremost among dangers to a plantation, especially if trees are planted along a road. Firebreaks give a measure of protection and should be built and maintained around the plantation. They can be cleared with a plow or disk and should be at least 8 to 10 feet wide. The firebreak should be disked periodically to keep it free of grass and weeds, especially during the spring and fall fire seasons.

Sometimes trees are attacked by insects or diseases. Owners should check their plantations periodically for disease symptoms or insect outbreaks. Most insect damage is first noticeable in late June or early July. Various kinds of sawflies, budworms, or tip weevils are the most common types of insects that attack coniferous trees.

Look for loss of needles or wilting leaders (the topmost shoot). Get in touch with a local forester to identify the insect and make control recommenda-tions. Spraying with one of the common insecticides often does a good job of controlling insects.

Livestock should be kept out of the plantation. Horses like to chew the bark, often girdling and thus killing the tree. Cattle will browse on the tree foliage. Hogs will root up the soil, causing considerable damage to the feeder roots located just beneath the soil surface. Sheep and poultry will nip off the buds. Livestock will also compact the soil, preventing rainfall from infiltra-ting the soil. Much of the rainfall normally reaching the roots will run off and may even cause soil erosion. Insufficient soil moisture results in reduced tree growth and dead trees.

Deer also may browse on young seedlings, and mice frequently girdle young trees during the winter. Rabbits are another scourge. There are repellents on the market designed to discourage animals from browsing young seedlings. Varying degrees of success with chemicals have been reported.

Figure 6. Gopher damage to the roots of a pine tree.

Pocket gophers may kill well-established conifers and hardwoods. They are a serious threat to plantations in all parts of the state, except for extreme northeastern Minnesota. Losses are most noticeable in the fall and spring, when animal activity is at its peak. Gophers feed on the roots (figure 6). Symptoms of gopher damage appear in the needles, which first turn a pale grayish green and finally turn brown. Damaged trees often lean to one side because the roots have been severed. Trees showing symptoms of gopher damage can be easily lifted out of the ground.

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Chemical Weed Control

The development of new, selective chemical herbicides offers an effective method of controlling weeds and grasses in plantations. These materials relieve the landowner of the time-consuming task of cultivation.

Simazine (trade name Princep) is a preemergence weed killer for control-ling most grasses and broad-leaved weeds. It is safe to use around most trees and shrubs. However, it is not recommended for any species of poplar, lilac, or willow.

Apply simazine before weeds emerge. In established plantings, apply the chemical in late fall or early spring. In new plantings or clean-tilled ground, make applications during or after tree planting, before weeds emerge.

The chemical may be applied over the entire planting site or in a band over the tree rows. Center the bands over the tree in four-foot widths. If you use narrower bands, tall weeds will fall across the treated strip and cover the trees.

Do not use simazine more than once a year. It is not recommended for trees under three years of age from seed (or less than 3-0 stock).

Amizine is a combination of a postemergence herbicide and simazine. This combination is particularly effective in cleaning up plantations that are overgrown with weeds and grasses.

Apply arnizine on growing weeds during the early part of the growing season or before weeds have matured and gone to seed. Do not spray amizine on any tree foliage. Use a directed spray to prevent contact with the leaves and needles of your trees.

Dichlobenil (trade name Casoron) is also a preemergent type of herbicide. Whereas simazine may be applied in either spring or fall, Casoron works best when applied in the fall. The granular form is recommended. When Casoron is applied after frost and freezing temperatures have occurred, no soil incorporation is necessary.

Glyphosate (trade name Roundup) is applied as a spray on the foliage of actively growing vegetation. It is not selective, so keep spray drift from getting on the trees and shrubs.

Trifluraline (trade name Treflan) is another frequently used preemergent herbicide which is particularly effective on grasses and less so on broad-leaved weeds. After application, Treflan must be incorporated in the upper one to two inches of soil.

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Governmental Assistance Programs

The federal government provides cost sharing or incentive payments for certain conservation practices on privately owned lands. Tree planting and site preparation for tree planting are two practices for which cost sharing is allowed. This program is administered by the Agricultural Stabilization and Conservation Service (ASCS). You can obtain information on how to participate in these programs at ASCS offices located in county seats.

Payments for these practices differ from year to year. They also vary according to the planting method and site characteristics. Certain specifications-spacing, choice of species, and selection of site-must be met. The Minnesota Division of Forestry is responsible for checking your land to determine whether tree planting is allowable. The Division checks again after planting to insure that the job was done according to standards set up for the practice.

To be eligible for ASCS cost sharing, make application before you start the project. For cost sharing on tree planting, you are urged to apply in person at the county ASCS office when you order your trees. The best time to do this is during the fall so that arrangements and delivery are completed in time for spring planting. The ASCS office manager will be glad to explain any program details to you.

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This bulletin covers only general information about tree planting. The extension foresters or county extension educators can give additional facts about tree planting to fit your particular case.

The web version of this publication matches the 1981 print version.