(Credit: Southwestern University)

An ancient Chinese proverb maintains that "the best time to plant a tree was 20 years ago; the second-best time is today." Just because July has arrived, there is no need to stop planting trees and shrubs. Early spring and late fall normally are the traditional times for planting woody ornamentals. However, with the development of different methods of growing nursery stock and modern transplanting equipment, planting at other times of the year has become possible and may be quite desirable.

Nursery stock that has been field-grown, dug, then balled and burlap wrapped may be planted into the landscape any time they are available. Although there is some root loss when the trees or shrubs are dug, modern practices such as root pruning in the field help to force roots to grow in the ball of soil that will be dug, thus easing transplanting shock.

Nursery stock that is balled-and-burlapped suffer severe root loss during the digging process. This makes it difficult for the plants to get the water they need to become established. (Credit: Louisiana State University)

Container-grown plants also are candidates for planting at any time of the year also. All of the roots currently supporting tree or shrub growth are in the container. Therefore, transplant shock is minimal given proper planting and watering practices are followed.

Container-grown nursery stock has the advantage of retaining all of the roots supplying the plants with water and nutrients during their production. This reduces transplant shock. (Credit: Texas A&M University)

Bare-root stock, however, is best planted during the dormant season. Because they have suffered more root disturbance, they are slower to become established in the landscape during the heat of summer.

Bare-root nursery stock suffers very severe root loss during the digging process and should only be planted during the dormant season. (Credit: Iowa State University)

Some woody species make most of their root growth in spring. Therefore, planting at other seasons of the year is less desirable. Included in this group are birches, flowering dogwood, golden rain tree, tulip tree, magnolias, black gum, white oak, willow oak, English oak, and red oak. When these species are planted at other times of the year, more attention to watering may be required during their first season of growth.

When planting trees and shrubs, a wide, shallow planting hole is preferred. Most trees exhibit dense root growth from 5 to 15 inches below the soil surface. Anchoring roots are mainly at a depth of 3 feet, although actual depth varies with density and aeration of the surrounding soil. Root systems do not mirror the top growth of a tree or shrub but often grow much wider than the top growth but not nearly as deep. The outline of the shoot and root system of a mature tree or shrub looks more like a water goblet than an hourglass. Therefore, a wide, shallow hole is preferred rather than a narrow, deep one that may be only slightly wider than the soil ball (or nursery container) around the roots being planted.

When planting trees and shrubs a shallow but wide hole is preferred. (Credit: Iowa State University)

The area that is dug up for planting new trees and shrubs should be improved by the addition of organic matter. However, it should become a transitional area between the existing growing medium around the roots and the native soil in the area. Allow the edges of the planting area to remain rough and irregular. A smooth wall of tight clay at the edge of a planting hole will make it difficult for your roots to penetrate and they may begin to circle within the hole.

Do not plant trees or shrubs deeper than they have been growing and, ideally, plant slightly shallower to allow for settling. Organic matter will gradually decompose in the soil ball as well as the surrounding improved area. The native soil and mulch materials will gradually settle in to replace it, and native soil will become the main growing medium.

Plants that may have been produced in containers may have some roots that are circling the container. If this is the case, these circling roots should be pulled if not too numerous, or cut if abundant, so they will not continue to develop circling roots.

Nursery stock produced in containers should be checked for roots that might have grown in a circular pattern. (Credit: Iowa State University)

If the weather is hot and dry when planting, spraying over the leaves of the tree or shrub during the hottest part of the day will help to ease stress. If the plant is small, a shade screen of some sort can be beneficial during the first few weeks of establishment, or until cooler weather returns. New roots should be kept moist but not overwatered since they are very delicate and easily can be suffocated by excessive watering. Mulch applied over the planting area will lessen watering frequency and keep the soil cooler and in better condition around the plant.

Adequate and proper watering is critical for the successful establishment of trees and shrubs. (Credit: Iowa State University)

Currently, there seems to be considerable disagreement about whether to wrap tree trunks after planting. Generally, it appears that young trees or shrubs with bark subject to sun scald benefit from this protecting during the summer. A tree trunk that has experienced severe sun scald may eventually heal, but the damaged wood will be part of the tree for its entire life and may allow rots to get started. Some authorities fell more borers are attracted to wrapped trees, but borers normally are attracted to any tree not growing vigorously—so any newly planted tree is attractive to them.

When trunks are wrapped, damage can be done by wrapping too tightly, or more often, tying too tightly at the beginning and ending of the wrap. In any case, wraps normally are not necessary for more than the first season, and a large increase in trunk diameter usually does not occur the first year after planting. With intense heat and a thin leaf canopy, wraps can relieve plant stress of midsummer planting. Paper wraps or plastic guards are quite satisfactory and easy to use.

Also, pruning trees and shrubs should begin when they are planted. Remove injured or poorly placed branches, and branches with narrow angles with the trunk. Remove lower branches gradually, never limbing up more than one-third of the way up the trunk in any given year. With the natural form of plant in mind, envision the types of cuts that might be made to encourage the plant to grow in an aesthetically pleasing way into the space provided for it.

In closing, there is an ancient Greek proverb that says, "A society grows great when old men plant trees in whose shade they shall never sit." When you plant a tree today, you give a green gift to the next generation. It is vital to plant and nurture the tree with great care. This ensures the sapling survives and grows to give shade and clean air for years to come.