September is a great time to plant trees and shrubs. It is cool enough to prevent heat stress on the plants, and the soil is warm enough to promote rapid root development before heavy frosts at the end of October.
When planting a tree or shrub, the hole needs to be only as deep as the root ball that will be placed in it. The soil can be loosened deeper and wider as well — up to three times as wide as the root ball.
One of the major causes of young tree death is planting a tree too deeply. If the soil comes up too high and surrounds the trunk, the trunk will rot. By far, a too-deep planting is the No. 1 cause of tree death that WSU Master Gardeners see in the Plant Clinic.
Soil should not be amended with compost or anything else. Plant the tree or shrub in the soil in which it will grow. If the soil is amended, the roots will stay in the richer soil and not work their way out of the hole. A more serious problem is that the amended soil is a different consistency than the native soil, and water will not move readily from one type of soil to another. Water stays put and creates a swimming pool that drowns the plant’s roots.
In addition, do not add fertilizer to the hole. How would you like to run a 100-yard dash with a broken leg? A newly planted tree or shrub is fragile, and fertilizer will not allow the plant to orient itself to its new environment.
When planting the tree or shrub, remove it from ALL of its wrappings and pots. The roots do not move easily through burlap or wire cages. Loosen the roots either with a hand rake, or by swishing the smaller plants in a large tub of water. Roots that are growing in a circle inside of their original pot will not loosen themselves. Circular roots can in a few years choke the tree and kill it. Mulch the soil by adding straw, grass clippings or compost to the surface around the tree. Do not let the mulch touch the trunk of the tree.
If you choose to plant a tree in your lawn, be aware that watering requirements for trees and lawns are drastically different, and trees often develop root rot from excess water. In addition, remove the turf at least 2 feet wide around the planting hole and mulch it. As the tree grows, be sure to maintain that 2-foot open area to prevent weed whackers and lawn mowers from tearing the bark.
Now you are confident about planting the tree, so consider where the tree will be planted in your yard. Trees grow tall and shade your yard and your neighbor’s yards, thus they change the environment in quite a large area. A more serious consideration is that the tree’s roots do not respect fences.
A mature tree’s root system can reach laterally 1 1/2 times the tree’s height. That is pretty invasive. My neighbors on one side of my yard have a 50-foot silver maple whose roots entangle all the plantings in my yard. My other neighbor has foolishly planted a ponderosa pine 1 foot from the fence line, which is not even enough room to allow for trunk growth. Be a good neighbor as you consider the place for your tree.
More importantly, remember that trees imperil utility lines. Many of the utilities in North Central Washington are on 35-foot poles. When trees tangle in the lines, two things happen — the branches cause a power outage, or the PUD trims the tree into an odd and unshapely one-sided plant.
So consider what type of tree you want in your yard and why — Shade? Color? Privacy? Fruit? Bird habitat? Wildlife interface? After you have figured out the purpose for the tree, the Master Gardeners can suggest species that will serve your purpose and will thrive in this area.
New plantings of trees and shrubs will extend the beauty of your landscaping. Trees have a definite life span, and when all the trees and shrubs in your yard are the same age, you will see your landscaping decline. New plants provide interest and vigor in your yard. Now is the time to plant.
A WSU Master Gardeners of Chelan County column appears weekly in the At Home section. Bonnie Orr is one of three columnists featured.