April is a good time to begin planting trees and shrubs in Chicago-area gardens. It's also the month to celebrate Arbor Day, a holiday dedicated to planting, caring for, and honoring trees. This year the day falls on April 26.
Be a tree champion this Arbor Day and every day by planting a tree with expert tips from the Plant Clinic:
Choose the right tree or shrub. Different species have different needs, so make sure that the species or variety you choose is a good match for the sunlight, soil, and available space of your site. The Arboretum’s Northern Illinois Tree Selector can help you choose a tree suited to our region. For a wider range of plants, the Arboretum offers a more general resource.
Allow enough space. Read the plant label to find out how wide and tall the plant will eventually grow. Put the plant where it will have enough space when it is full-size.
If soil is wet, wait. Digging when the soil is wet can damage its structure, making it a more difficult environment for roots. If rain or melting snow saturates the soil in spring, wait to plant until water has drained and the soil is just moist.
Measure the root ball. Whether the tree came in a pot or tied up in burlap, you will need to know the width and depth of its ball of roots. Measure the depth from the root flare—the place where the trunk or stems flare out to the roots. That place may be buried when you buy the plant, so dig down to find the root flare and measure the depth of the root ball from that point.
Dig a wide, shallow hole. The hole should be two or three times as wide as the root ball. It should be as deep as the root ball but no deeper. The hole should be saucer- or bowl-shaped rather than bucket-shaped.
Trim the roots. If the plant came in a container, remove it from the pot. With a sharp knife, shave a thin layer, about an inch, from each side of the root ball. These cuts will encourage new roots to grow out into the soil. Otherwise, try to keep the root ball intact as you place it in the hole.
Remove burlap. If the tree was wrapped in burlap, place it in the hole before you cut away as much of the burlap and wire basket as you can reach. Trees wrapped in burlap are usually large and heavy, so get someone to help and handle the plant carefully.
Get it straight. Walk all the way around the plant to check that it is centered and straight in the hole. If it is near a wall or fence, turn it so the best-looking side can be seen.
Don’t plant too deep. Double-check that the root flare will be at or slightly above the level of the surrounding soil. Planting too deep is a major cause of tree problems.