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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Selecting Trees and Shrubs

This article was published originally on 8/10/2005

Late summer/early fall is the time for good sales on many trees and shrubs. However, many people buy trees and shrubs from a garden center or nursery without knowing the basics for selecting high quality nursery stock. Here are some suggestions on how to select healthy trees and shrubs.

Overall Appearance

The first step is to observe the overall appearance of the tree or shrub. Does the plant have off-color foliage (yellow, brown or grey-green leaves)? Is it wilting? A wilting plant is a good indication that the plant has not received proper care or there is something wrong with the root system. Vigorous trees will have a healthy foliage color and a full, lustrous appearance.

Some plants naturally have yellow-colored foliage (‘Princeton Gold' maple) or droopy leaves (black maple). Ask garden center personnel if you are not certain of the plant's normal leaf color or growth habit.

Branches

Look for plants that are evenly branched on all sides. If the tree or shrub is flat on one side, it will be difficult to prune in such a way to make it symmetrical. In most cases, if the branches are clustered at the top of the tree, the plant will not produce more branches below. Also, look to see if there are any broken or rubbing branches. This indicates poor care or pruning.

Living Tissue

If you are shopping in early spring and the trees are still dormant, scrape away a tiny bit of the bark on a branch with your fingernail. The tissue beneath the bark should be green. Brown tissue usually indicates a dead branch. Additionally, a live branch is usually flexible, while a dead branch will snap. Buds present since last summer should be swollen and plump. Trees with obvious insect or disease problems should be avoided.

Growth

Look for trees with healthy growth from year to year. You can check last year's growth by looking for the bud scale scars (scars encircling the twig created when the bud scales on the terminal buds fall off in spring). From the tip of the twig to the bud scale scar indicates the amount the tree grew last year. Small amounts of growth (less than 4 inches) are sometimes an indication the tree or shrub is in trouble. This is highly dependent of species as some plants naturally grow at a slower rate. Ask the sales person how rapidly the tree or shrub typically grows.

Trunk

A healthy trunk should be straight, undamaged, and have no signs of injury. If the trunk is wrapped, ask garden center personnel to remove the wrap so you may look for sunken areas of bark or any other injury.

Root System

Avoid trees that appear too large for their container and balled and burlapped plants with extremely small root balls. There is a possibility that the tree could be root bound. Root bound trees and shrubs often have circling roots which can girdle a tree or shrub if left uncorrected. Industry standards state that a tree that is 1 inch in caliper should have a root ball 16 inches in diameter.

Check that the tree or shrub is well rooted. Grasp the trunk near the base and try to move the tree or shrub in the container. Well-rooted plants should not create a hole in the soil when the stem is moved; the container and the plant should move together. With the help or consent of garden center personnel, examine the plant's root system by carefully removing the pot. Healthy roots are firm and lighter in color than the surrounding soil. Roots that have a foul odor or are mushy indicate a disease problem.

Balled and burlapped trees and shrubs are basically checked in the same manner as container grown shrubs and trees. Look for cracks in the root ball or large amounts of loose soil. If you see this, it could be an indication of poor handling which could mean problems in the future.

Transporting

When transporting your trees and shrubs, be sure to carry them by their container or root ball rather than by their trunk to avoid damaging their root system. Lay the trees down in the bed of the truck if possible. Exposure to strong winds in the back of an open truck bed can dry and tear foliage, so cover or wrap plants that will be transported in a truck or other open vehicle. If you are unable to cover the plants, drive at a slower speed (less than 35 mph) to prevent serious injury. Also, be sure to water the plant thoroughly when you get home.

Using these guidelines when purchasing plant material will increase the chances that your plants will thrive in the landscape.

Page References: 
93-94
Year of Publication: 
2005
Issue: 
IC-493(19) -- August 10, 2005