Tree Planting

Sunday, September 29, 2019 8:49 AM

I have heard that fall is a good time to plant new trees. If so, what do I need to do to be successful?   Jerry W., Jenks

Fall is clearly the best time to plant most container-grown deciduous trees as well as those with balled and burlapped (B&B) root balls. This is because, in the fall, trees have huge energy stores that are used for growing new roots rather than producing leaves and fruit. This will allow the tree time to develop a root system that is much better able to handle the summer stresses of next year’s growing season. Also, although the air temperatures are dropping, the ground temperatures are still warm enough to encourage good root development for some time. The exception to this rule is that both evergreen trees and bare-rooted plants should be planted in early spring.

Of all of the newly planted trees that die in the first few years, the problem is almost always due to faulty planting techniques and inadequate aftercare.  So, let’s discuss this.

First, it is best to dig a very wide but shallow, saucer-shaped hole that is 2-3 times the diameter of the tree’s root ball but no deeper than the root ball itself. If you simply dig a hole the size of the root ball, particularly in clay soil, it will be like planting it in a clay pot and the tree will be either too dry or too wet much of the time. If you are planting in shallow clay soils, the hole depth should be shallow enough to elevate the crown of the root ball 2-3 inches above grade in order to help with overall root system drainage.

When planting trees, it is recommended that you use only native soil for backfill. Studies have shown that trees do better if no amendments are added back to the native soil at the time of planting, as it may delay establishment and promote disease. If you decide to fertilize, apply a slow-release type only to the top of the soil after planting.

Eliminating grass from the tree’s base significantly improves their growth rate and health. After planting, apply 2-4 inches of loose mulch in a 4-6-foot circle around the base of the tree and keep it well mulched for the first three years. This circle will keep unwanted grass away from the dripline and commercial weed eaters away from the tree trunk.

All newly planted trees need supplemental watering for the first three years until a mature root system develops. They need at least one inch of water per week, and more if extremely hot and windy conditions exist. Wilting of the trees’ leaves may indicate a need for more water but be aware that too much water can also produce wilting. If in doubt, simply feel the sub-soil.

If the tree is on a slope or in a windy area, stake it only until the tree feels firm in the ground, which could take up to one year. After the first growing season, remove all stakes and ties.  If not removed, the stakes will adversely affect the tree’s structural integrity and delay tree growth.

For more detailed information on this subject, see OSU Fact Sheet L-440 (Tree Planting Guide).