These tricks help trees planted in autumn survive

In the last week, three people asked whether it is too late to plant a tree, while a fourth reader asked whether she could transplant a crab apple this time of year. In every case, I encouraged them to plant, provided they followed a few simple guidelines to ensure success.

First and foremost, if planting a new tree, purchase a small one, 1 to 2 inches in trunk diameter. Small trees establish adequate root systems more rapidly than large trees and ultimately catch up in trunk diameter with initially larger trees.

Dig the planting hole at least twice as wide as the tree’s root ball. Do not dig it deeper than the root ball; the loosened soil under the tree will settle and so will the tree.

The newly planted tree should show an obvious trunk flare at the soil surface. Before planting a ball-and-burlap tree, remove any soil that was piled up on top of the root ball during harvest and wrapping. This added soil disguises the trunk flare, making it easier to plant the tree too deep. Avoid purchasing a container-grown tree that does not show an obvious trunk flare – it may have been planted too deep in its pot.

Do not amend the backfill soil with organic matter; use only the native soil that came out of the hole. The only exception is when the native soil is almost totally sand or clay, when up to 25 percent by volume of organic matter should be added to the backfill.

Mulch at least out to the drip line, starting a few inches from the trunk. Do not pile mulch at the base of the trunk.

Minimize pruning at planting. Healthy root growth next spring depends on chemicals transported from an abundance of leaves to the roots. When planting in the fall, remove only obviously dead, damaged, and diseased branches, delaying other pruning until after the establishment period (one year for each inch of trunk diameter).

Do not fertilize your fall planted tree. Even after establishment, do not fertilize a tree unless growth completely stops or the foliage shows signs of nutrient deficiency. Then have the soil tested to make sure the problem is lack of nutrients in the soil.

Fall transplanting of existing trees involves the loss of a substantial portion of the tree’s root system and thus your chances of success increase as the trunk diameter decreases; trees of less than 2 inches in trunk diameter will transplant with less branch die-back than larger trees. Still, I have successfully transplanted larger trees (3 to 4 inches trunk diameter) in fall by digging as big a root ball as possible and watering diligently the next spring, providing an inch of water every week for the first growing season.

Deciduous trees planted in spring must establish a new root system while supplying emerging leaves with water and nutrients. Fall planting, on the other hand, allows time for development of new roots after the leaves have dropped, allowing the tree to allocate more resources to root development. Many tree species, such as sugar maple, continue producing new roots until the soil freezes. A tree planted in early October may have six or more weeks of new root development before winter closes in.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to rmanley@ptc-me.net. Include name, address and telephone number.