Trees can be obtained from the nursery in many forms—bare root, container-grown, balled and burlapped, or dug by tree spade. Transplanting can be successful with all forms. Always put extra effort into the planting process to ensure a good start for your tree. The faster the root system is re-established, the better the chances for survival, and the more rapidly it will grow.
THE PLANTING SITE
Planting too deep is one of the most commonly encountered problems of landscape trees. It is not uncommon for trees to come from the nursery with the roots already too deep in the root ball. If the existing soil from the planting hole has a high clay content and is not friable (crumbly), it should be amended with up to 25 percent composted organic matter (leave mold, compost, peat moss) before backfilling the hole. New roots will grow faster in a light, welldrained soil mixture.
In poorly drained, compacted soils, typical of modern housing developments, improved drainage may be needed. The planting hole can hold water like a bucket. More urban trees die from too much water than from not enough water. To test the drainage of your planting hole, pour a few gallons of water in the hole before planting the tree. If it hasn’t soaked in after an hour, you have a drainage problem. If the hole is near a slope, you may be able to run a small, underground drain pipe from the bottom of the planting hole to lower down on the slope.
The planting hole should be wider than the roots or root ball, two to three times wider is recommended.
Don’t dig the hole any deeper than the depth of the roots or root ball because the tree needs support from underneath to stabilize it. Make sure the root collar, or area of the trunk that flares out near the soil line, is visible. The uppermost lateral roots should be just below the soil surface.
The sides of the hole should slope up gradually, making it saucer- or bowl-shaped.
Container or bare-root plants
Remove plant from container or packaging material and inspect the root system for dead or injured roots. Remove damaged roots and cut back spiraling roots to encourage proper development.
Center the plant in the planting hole. Keep it straight with the branches pointing in the direction you want them to grow.
Backfill the planting hole with prepared soil, gently filling around the roots to eliminate air pockets.
With remaining soil, create a saucer or water basin around the outer edge of the soil ball. This will keep water in the root zone and prevent run off.
Once the plant is in the hole, remove twine and cut as much burlap as possible. If the plant is in a wire basket, remove as much wire as possible.
Work the prepared soil firmly around the soil ball, but do not compact.
Follow procedure for container plants (previous page).
Fertilization at the time of planting is generally not recommended. Research has shown that fertilization is ineffective until the tree has had time to partially re-establish its root system.
SEASON TO TRANSPLANT
Spring is the best season for transplanting. The longer growing season allows roots to re-establish before winter. Fall also is considered a good time to plant, but some species do not transplant well in the fall (e.g., birch, magnolia, poplar, redbud). Summer planting is possible if a judicious watering program is followed, particularly if the plants were dug from the nursery in spring or grown in containers.
A circle of mulch, 3-4 inches deep, with a diameter at least four times the diameter of the root ball, should be placed around every newly planted tree to conserve soil moisture and help moderate soil temperatures. Studies have shown that mulching can nearly double the growth-rate of trees in the first few years after planting. Do not mound the mulch or let it rest against trunk of tree.
When stability is a problem, trunks of trees should be staked for 1-3 years until new roots stabilize the tree. Avoid staking too rigidly. Guy wires or staking materials should be checked monthly during the growing season to prevent damage to the bark. Failure to loosen or remove staking wires has girdled many trees.
Young trees and trees with thin bark (e.g. maple) can be damaged by very cold weather or warm winter sun. Stems can be protected by wrapping trunks in late fall, from the bottom up so that the wrap overlaps like shingles. There are numerous tree wraps and loose tree collar wraps available commercially. Remove the wrap each spring.
It is very important to ensure the best possible branch structure while trees are young. At the time of planting, be sure to remove all rubbing branches and dead branches. Side branches of trees with a central leader should be evenly spaced up and down the trunk. Do not allow more than one leader in shade trees or conifers.
Proper watering is the single most important aspect of maintenance of transplanted trees. Too much or too little water can cause damage. In the first few months after planting a tree, most of its moisture comes from the root ball. The root ball can dry out in only a day or two, even if surrounding soil remains moist. The only way to know is to probe the soil in the root ball and check its moisture. A metal rod or soil probe is good for this. Even after trees are well established, they should be watered generously during periods of low rainfall (e.g. every 7 to 10 days).
Research has shown that a tree can lose up to 95% of its root system as a result of transplanting. This causes a great deal of stress. After transplanting, the tree may form fewer and smaller leaves and grow very little. How long the stress period lasts depends on the size of the tree, its site, and the care it is given. A small tree (2-3 inch diameter), planted on a good site and given adequate water, should return to vigorous growth in 2-3 years. A poor site or inadequate care will lengthen this period. Large trees take longer to recover from transplanting than small trees; approximately 1 year of recovery is needed for each inch of diameter. As long as branches are not dying and growth improves each year, the tree is doing well.