Get It Growing: Fall is for planting trees & shrubs

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I wish more gardeners understood that fall is a primary planting season in Louisiana. For years horticulturists have tried to get the word out that November through February is the ideal time to plant hardy trees, shrubs, vines and ground covers in the landscape. Planting in late November and early December is especially good because trees and shrubs planted now benefit in several ways.

These plants are dormant during this time of year and are less likely to suffer as much from transplant shock. In addition, the cool weather and regular rainfall typical during the Louisiana winter allow new plantings to settle in and adjust with little stress – and less work for you watering them. Hardy trees, shrubs, ground covers and vines are not damaged by normal winter freezes, even if they’re newly planted.

The roots of woody plants will actively grow during fall and early winter, so planting in fall allows them to become well-established prior to spring growth. By May of next year, trees and shrubs planted over the next six weeks will have developed better-established root systems than those planted next spring, and this will increase their ability to absorb water and survive that first stressful summer after planting.

Selecting trees for the landscape

No one tree is perfect. All trees have advantages and disadvantages, depending on the planting location and desired characteristics. Here are some points you need to consider:

1. Select a tree that will be mature at the appropriate size. A small patio might benefit from a small 25-foot-tall tree planted nearby but be completely overwhelmed by a larger tree. Planting a tree that will grow too large for its location is one of the most common mistakes people make, along with planting too many trees. Find out what the mature size a tree will be before you plant it. (This really applies to any plant selection, including shrubs, vines, perennials and bedding plants.)

2. Think about the purpose of the tree and why it is needed. This will help you determine the characteristics the tree should have, such as its shape, size and rate of growth. Also consider ornamental features, such as flowers, attractive berries, brightly colored fall foliage or unusual bark.

3. Decide if you want a tree that retains its foliage year-round (evergreen) or loses its leaves in the winter (deciduous). Deciduous trees are particularly useful where you want shade in the summer and sun in the winter. Small-to-medium-size evergreen trees are useful as sound barriers or privacy screens.

4. Choose trees that are well adapted to your local growing conditions. They must be able to tolerate long, hot summers and mild winters, which make unsuitable for our area a variety of northern species you might see in catalogs. Trees that are not completely hardy are not good choices either.

5. Don’t forget to check the location of overhead power lines. If you must plant under them, choose small, low-growing trees. Also consider walks, drives and other paved surfaces that may be damaged by the roots of large trees. Locate large trees at least 15 feet away from paved surfaces and your house.

Tree-planting guidelines

Planting trees properly is not difficult but can make the difference between success and failure.

Whether the tree is balled-and-burlapped or container-grown, dig the hole at least twice the diameter of the root ball and no deeper than the height of the root ball. When placed into the hole, the root ball should sit on solid, undisturbed soil.

Remove a container-grown tree from its container and place the tree in the hole. A root ball tightly packed with thick encircling roots indicates a rootbound condition. Try to unwrap or open up the root ball to encourage the roots to spread into the surrounding soil.

Place a balled-and-burlapped tree gently in the hole with the burlap intact. Once the tree is in the hole, pull out nails that pin the burlap around the root ball, remove any nylon twine or wire supports that may have been used, and fold down or remove the burlap.

Whether planting a container-grown tree or a balled-and-burlapped tree, the top of the root ball should be level with or slightly above the surrounding soil. It is critical that you do not plant the tree too deep.

Thoroughly pulverize the soil removed from the hole and use this soil – without any additions – to backfill around the tree. Add soil around the root ball until the hole is about half full, then firm the soil to eliminate air pockets, but do not pack it tight.

Finish filling the hole, firm again and then water the tree thoroughly to settle it in. Generally, we do not fertilize newly planted trees.

If the tree is tall enough to be unstable, it should be staked, otherwise it’s not necessary. Firmly drive into the ground two or three stakes just beyond the root ball. Next, tie cloth strips, old nylon stockings or wire (covered with a piece of garden hose where it touches the trunk) to the stakes and then to the trunk of the tree. Leave the support in place no more than nine to 12 months.

You should keep the area 2 feet out from the trunk mulched and free from weeds and grass. This encourages the tree to establish faster by eliminating competition from grass roots. It also prevents lawn mowers and string trimmers from damaging the bark at the base of the tree, which can cause stunting or death. The mulch should be about 2 inches deep and pulled back slightly from the base of the tree.

Dan Gill is a horticulturist with the LSU AgCenter. He can be reached at DGill@agcenter.lsu.edu