Planting Trees in the Fall

Planting Trees in Fall

Allen Robinson: Ask a Master Gardener

Tuesday, October 31, 2017

Q: I have heard that fall is a good time to plant trees. Is that true? If so, what do I need to do to be successful? Roger L., Broken Arrow

A: Fall is clearly the best time to plant most container-grown deciduous trees and those with balled and burlapped root balls. In the fall, the trees have huge energy stores that may be used for growing new roots, rather than producing leaves and fruit. This will allow the tree to enter the following growing season better able to handle the summer stresses. 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 evergreen trees and bare-rooted plants should be planted in early spring.

Of all the newly planted trees that die in the first few years, the problem is almost always due to faulty planting techniques and inadequate aftercare.

First, it is best to dig a wide but shallow, saucer-shaped hole about three times the diameter of the tree’s root ball and 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 similar to planting in a clay pot, and the tree will be either too dry or too wet much of the time. If you are planting in high clay soils, to help with root system drainage, the hole should be shallow enough to elevate the crown of the root ball 2-3 inches above grade.

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, 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 its growth rate and health. After planting, apply 2-4 inches of loose mulch to a 4- to 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 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 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 the stakes. If not removed, the stakes will adversely affect the tree’s structural integrity and delay tree growth.

Garden tips

• Keep leaves off newly seeded fescue to prevent damage to the sprouts. Also, the soil of newly seeded fescue should kept moist until the sprouts are about 2 inches, then water less often and for longer times to encourage deep root growth of the seedlings.
• Remove garden debris to prevent many garden pests and diseases from overwintering in these materials.
• Plant cool-season cover crops like Austrian winter peas, wheat, clover and rye in otherwise fallow garden plots.
• Cover water gardens with netting to keep out falling leaves.