Spring is a good time to plant trees. But many trees are planted too deeply. This prevents needed air and water from reaching the roots and can cause the tree to decline and eventually die.
To determine the proper planting depth for your new tree, locate the trunk flare -- the place where the trunk widens at ground level.
If the trunk flare is not showing on a balled and burlapped tree, open the burlap to find the flare. You may need to very carefully remove the excess soil above the roots to expose the flare.
It is wise, especially in heavy clay soils, to plant the tree a little high in the hole. Generally, planting the tree so the flare is 2 to 3 inches higher than ground level is a good idea. Dig a wide, shallow hole that is only as deep as necessary.
It is best not to amend the backfill going back in the planting hole; refill the hole with the same soil you removed. But it is OK to amend the soil at the surface around the tree.
Whether trees or perennials, plants that have been grown in containers should be moist when planted in your garden.
When you remove the plant and its root ball from the container, spread out or cut all roots that have circled inside the pot. These roots could eventually girdle or choke the plant if not redirected to grow out and away from the plant.
Monitor watering needs carefully after planting, as the lightweight container soil in which many plants are grown can dry out quickly and stress the plants. Generally, containerized plants need more frequent but light watering to get them established with roots growing out into the garden soil.
Containers for seasonal plantings must have at least one bottom hole for drainage. A layer of gravel in the bottom of the container is not necessary.
Fill the container with a lightweight, fast-draining soilless mix; avoid heavy garden soil. Leave enough space between the top of the growing medium and the rim of the pot to allow water to collect and soak in.
Very large containers can be partially filled with wood chips or empty plastic pots to conserve soilless mix. Separate the wood chips from the growing mix with landscape fabric.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.