Trees, shrubs and vines

Trees, shrubs and vines

Trees, shrubs and vines serve many purposes and offer numerous benefits including shade, screening for privacy and windbreaks, and noise reduction. They also provide shelter for a variety of wildlife. Groundcovers can visually define a space or provide texture and color to a landscape. In this section, you’ll find useful information on how to select and care for your valuable landscaping plants.

Planting

Time of year to plant

Early spring and early fall are the best times of the year to plant because plant shoot growth is minimal and roots have time to become established after planting. Bare root plants should be planted before bud break in March, April or May. Balled and burlapped and container plants can be planted anytime of the year as long as the soil is not frozen. However, early spring or early fall are still considered the best times to install these types of nursery plants.

Where to plant

Select plants appropriate for the location in which they’ll be planted. Pay attention to the eventual mature height and spread of a tree or shrub, keeping in mind that some community ordinances may restrict planting of trees near power lines, parking strips, street lights, sewers, traffic control signs and signals, sidewalks and property lines.

Other questions to consider

• Will this tree or shrub drop leaves, flowers or fruit that may be a nuisance to neighbors?
• Will this plant receive the sufficient amount of sunlight in this location? Will it shade other plants?
• Will this plant share moisture requirements with the plants surrounding it? Is it compatible?
• What kind of care, including pruning, will this plant require?

Special planting needs

Bare root plants should be unpacked carefully and any broken roots should be cleanly pruned off. The roots can be soaked in a bucket of water for up to four hours and protected from heat and drying before planting. Do not prune any healthy roots now. Once the hole is dug and the roots spread out, any roots that are too long may be removed at that time to prevent circling or kinking.

Balled and burlapped plants should be handled carefully by the soil ball, not the trunk or branches, to prevent root and trunk damage. Once the plant is in the hole, twine, nails and excess burlap should be removed from the top of the root ball. Synthetic burlap and in-ground fabric bags should be completely removed.

Container plants should be kept in their containers until they are ready to be put in the ground to protect the roots from drying out or getting damaged. Fiber and pulp pots decompose slowly and should be removed completely or sliced before planting to avoid rot and drainage problems. Some plants may be pot bound or have roots that are matted together. To improve root growth into the surrounding soil make four to five shallow cuts around the root ball and loosen the roots on the sides and bottom of the root ball before planting. For severely pot bound plants, the butterfly method can be used.

Planting instructions

Dig the hole only deep enough to hold the root ball. When planting in loam soil, the root flare on the tree or shrub trunk is planted level with the surrounding soil. If you can’t see the root flare, remove soil or burlap until you do. When planting in clay soil, the root flare is planted 1-2 inches higher than the surrounding soil (see diagram). Alternatively, you can form a one-inch pedestal at the bottom of the planting hole for the root ball.

The planting hole diameter should be two times the diameter of the root ball. The minimum planting hole diameter can be 12 inches wider than the root system, and the maximum can be up to five times the root system diameter. The sides of the planting hole should be vertical. If the sides of the planting hole appear shiny or glazed, rough up the edges with a shovel to loosen the soil before planting.

Before adding soil back into the planting hole, make sure that roots are not kinked or circling. Start adding soil in 3-4 inch layers lightly firming the soil between layers by lightly stepping on the soil. Backfill soil may be mixed with organic matter at a rate of 3 parts soil to 1-part organic matter to help improve soil texture of medium or fine textured soil. Adding organic matter to the backfill soil is not always recommended, especially in a heavy clay, since sometimes roots will not leave a richly amended hole to grow into the adjacent inferior soil, and circling of roots may occur. Avoid covering the top of the root ball with backfill soil. Make a 2-3 inch soil berm around the edge of the planting hole to form a shallow basin. Water the plant in well by filling the basin with water. In heavy clay soils, watch that this berm drains within a couple of hours. Fertilization is not recommended at time of planting. Once the plant is well watered in, apply a layer of mulch 2-3 inches thick to the basin, avoiding placing mulch against the base of the trunk.

Pruning

When to prune

Selecting the proper time to prune is important. Heavy pruning at the wrong time of year can stimulate unwanted growth or prevent flowering or fruiting. Before pruning, consider time of year, type of plant and flowering periods of certain plants. See the table below.

Time of year to prune various types of plants

When to prune new growth on pines

Pines have buds only at the tip of the branches. If a branch is pruned after a growth flush and the terminal bud is removed, regrowth is impossible. Pine branches should be pruned or pinched in early summer when the new branch (candle) has begun to elongate but before the needle bundles open. This pruning causes the growth to be more compact but still allows buds to form for the following year.

Two basic types of pruning cuts

• Heading cut — Cutting plant stems back to a bud, twig or stub. Potential problems — a stub is often left and may become infested with insects or diseases, vigorous growth may be stimulated, and the new growth may be weakly attached and could split or crack under pressure. This may also negatively affect the desirable, graceful arching habit of some shrubs.
• Thinning cut — The removal of a branch at its point of origin or cutting back a branch to a lateral branch about 1/3 the diameter of the branch being removed. Advantages — No stub is left, the plant retains its natural shape, and vigorous new shoot growth is avoided. Caution: removing more than about 30% of the foliage can stimulate new growth even if thinning cuts are used.

Using thinning cuts on selected branches to improve light and air penetration to interior foliage.

Location of pruning cuts

The size of the branch determines the location of the pruning cut. A small twig or branch can be pruned back to a bud or lateral branch. On a small branch make the cut one-quarter inch above the bud and slant the cut away from the bud.

• Natural target pruning is the technique used when cutting beyond the bark ridge and branch collar (collectively called the branch shoulder). This cut provides a physical barrier to disease and injury within the intact branch shoulder. This compartmentalization of the wound stops injury from spreading into the main trunk of the plant where it could spread throughout the plant and be damaging to the plant as a whole. The wound size is also smaller allowing callus to grow quickly over the wound and limits potential exposure to insect and disease infestation.
• Large branches or limbs (those to heavy to hold while cutting) are removed by a series of three cuts. The first cut is made on the underside of the limb about 12 inches from the branch crotch and should go about one-quarter of the way through the limb. The second cut is made on the top side of the branch about 2 inches farther out on the limb from the undercut. Cut down until the branch cracks off. As you are completing the second cut, careful to watch for the branch suddenly dropping or moving quickly as the branch weight accelerates limb removal. The third cut is made on the top side of the stump left over, just outside of the bark ridge and branch collar. Be sure to support the branch stump when making the final cut to avoid tearing the tissue when completing the cut.

Pruning tools

Proper tools should be used to make a clean pruning cut and to minimize damaging plant tissue. If the plant tissue is crushed or torn it can leave the plant susceptible to disease and insect problems. In addition, more time will be needed by the plant to have tissues grow over the wound. Pruning tools should be the correct size for the job and be made of tempered steel that can hold a sharp edge. Making a pruning cut should be relatively easy when the correct size of tool is used. Hand pruners should be used to cut branches that are less than 1/2 inch in diameter. Lopping shears should be used for branches between 1/2 and 1 inch thick. A bow saw or pruning saw should be used to cut branches larger than 1 inch thick. Be sure to make a clean cut with the proper tool.

Sanitizing pruning tools

Pruning tools should be disinfected after each cut, under ideal circumstances, to avoid spreading diseases from plant to plant. At the very minimum disinfect pruning tools after finishing one plant but before beginning to prune the next plant. To sanitize tools, dip the cutting edge in a disinfectant solution such as denatured alcohol, methanol or diluted household bleach (1 part bleach plus 9 parts water). An alternative is to spray the cutting blade with a disinfectant solution. When using bleach, make sure to apply a thin layer of oil to the blade before storing to avoid rusting of the tool.

Pruning paints and asphalt emulsions are not recommended for use on pruning cuts as they may actually seal in disease-causing organisms or promote rot.