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Fall Tree Planting

This article was originally published on September 1, 2008 and expired on November 30, 2008. It is provided here for archival purposes and may contain dated information.

If you want to take advantage of mild fall weather and sales, fall can be a good time for planting trees and shrubs, said a University of Illinois Extension horticulture educator.

"Fall is also a time that seems to be less hectic," said Nancy Pollard. "You can increase your chances of success significantly with many trees and shrubs by using some good practices--proper planting depth, supplemental watering, and good mulching practices."

After selecting and purchasing the tree or shrub, she suggested sticking a tarp in your vehicle to protect the plant from drying winds during transport. And in picking out the tree or shrub, keep in mind the landscape purpose, available space, soil type, and sun or shade conditions it will face.

"Keep the plant well watered until transplanting," she added.

When it comes time to dig a hole for the new plant, the immediate question is, how deep?

"The tree trunk and root ball will tell you," she said. "While the tree is still in the container, look for the point where the trunk slightly flares out and the roots angle down--not at 90 degrees or up. Often this flare is buried accidentally by soil or mulch. You may need to excavate the root ball by hand down to the root flare.

"The natural flare should end up about two inches above the surrounding soil line when planted in clay or poorly drained soil, or exactly at soil level if the soil is sandy or loamy."

If the container is small, Pollard likes to dig the hole, set the container in the hole to see if the depth is too shallow, and when the height of the root flare is just right, remove the container so it can be planted.

"If the container is heavy--it should be if it has been watered--use a ruler or shovel handle to figure this out," she said. "The hole should be much wider than it is deep, more saucer-shaped, like the natural shape of the root system. Rough up the edges of the saucer-shaped hole as roots refuse to cross slick barriers. Skip the amendments, but do break up any large soil clods."

Next, it is time to remove the plant from the container, place it on a tarp, and tease the roots out with your fingers if the plant is not pot-bound.

"If you find a few circling roots in the ball, carefully unwind them and spread them in the wide hole," she said. "This prevents them from choking or girdling the tree just as the tree has reached the size you were dreaming about when you planted it."

If the roots prove too dense to tease out, make four one-inch-deep slices with a knife down the sides of the ball and through the bottom of the root ball as well. Then slide it into the hole.

"Backfill the hole with soil up to the base of the flare. Do not cover the root flare," she said. "I like to partially backfill, add water, allow it to drain, and then add the rest of the soil. Then water again. This eliminates air pockets and gets good soil contact with the root ball.

"Do not stomp on the hole because that limits root growth and makes a muddy mess of your shoes. Instead, let the water settle the soil."

Throughout the subsequent months, she added, consistent watering is critical. But do not overwater.

"Water deeply, as often as is necessary to keep the soil ball moist--about twice a week during warm weather, once a week during cooler weather. Water about every three weeks throughout the winter when there are thaws or if there is little rainfall," she said. "Winter winds continue to dry out the plants and the root system is limited.

"Checking the plants in the winter also helps you detect any frost heaving--particularly a problem in clay soils."

The new plant should be topped with a three-inch layer of mulch such as bark chips to conserve water and insulate the roots. It may also help reduce frost heaving.

"Spread the mulch," she said. "It will look like a flat, five- or six-foot-wide doughnut around the tree with the trunk in the center hole. Keep the mulch a couple of inches away from the trunk. Trunk bark is made to 'breathe,' not resist moisture and soil microorganisms as the roots do."

With care in tree selection, proper planting depth, and good watering and mulching practices, the majority of trees are able to overcome transplant shock.

"Water diligently the first spring and summer and during future droughts," she said. "If you follow these tips, you can expect decades of delight for your efforts."

Source: Nancy Pollard, Extension Educator, Horticulture, pollard@illinois.edu

Pull date: November 30, 2008

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