As eager as we all are to dig in the dirt and putter in the yard, there are some planting decisions that we mustn't rush or treat impulsively. These decisions will affect our gardens now, as well as over the next hundred years. "Where and how should I plant a tree?" and "What tree should I plant?" are two of the most important questions serious gardeners can ask.
These are the main areas of focus for both homeowners and professionals: careful study of the site; choosing the appropriate tree for that site; preparing the site; and planting the tree correctly. Proper tree maintenance is, of course, an integral part of long-term tree health, but more potentially damaging problems can occur during those first four steps than occur during the life of a tree.
Homeowners should first take a soil test, a good practice regardless of the type of plant material you are interested in. The test will measure the soil's pH as well as the amount of organic matter present. It's best not to amend or fertilize their soil before they know what they've got. If test results recommend amending with organic matter (3 percent organic matter is considered good), the ideal time is before the tree is planted. The entire planting area (not just the planting hole) should be cultivated to a depth of 1 foot, adding organic matter such as chopped up leaf litter, well-aged manure or, of course, rich compost. At all times, gardeners must refrain from throwing handfuls of peat moss into a planting hole, especially when drainage is poor.
The Planting Hole
One of the most significant mistakes often is made during the planting stage: a majority of trees are planted too deeply, a condition that has serious repercussions years later, when the tree inexplicably goes into decline. The shape of the planting hole — a saucer, not a deep hole — is all-important. Most tree roots are found within the top 12 to 24 inches of soil and can literally suffocate when confined to an overly deep hole in compacted clay, where the opportunity for oxygen exchange is nonexistent and the chance for the roots to grow outward is thwarted by impenetrable clay. Plant a portion of the root ball slightly above grade, gently sloping the mix of dirt and composted organic material away from the trunk.
Mulching the entire planting area with 2 to 3 inches of organic material is very important. This area includes the circle of ground between the trunk of the tree and the drip line, where the outermost branches end. Mulch conserves moisture for the tree, limits competition for water and nutrients from other plants growing under the tree, keeps weeds down, and protects the roots from foot traffic or mechanical injury. Mulch should not be mounded up against the trunk.
Make sure your tree is watered properly, not just its first year, but for all its life. A slow trickle from a soaker hose or a very slow sprinkler will put moisture right into the root zone, instead of wasting it as overhead watering does. Be on the lookout for signs of water stress with your trees and respond accordingly. Premature, yellow leaves during drought are the first indicator of water stress.
Fertilizer should be determined by the soil test. Avoid routine fertilizing since the soils in the Chicago area are already fairly rich in potassium and phosphorus. Again, take your cues from your tree. If it is very slow to grow, leafs out late, or has undersized leaves, flowers or fruit, it might need a boost. If so, apply the fertilizer in spring only. Trees situated in the middle of lawns usually receive enough nitrogen via the lawn fertilizer and shouldn't require any other.
Selecting the Right Tree
You can give your tree a head start by selecting from those that are proven winners in the Upper Midwest. If you have a larger site, perhaps wooded acreage, picking from the long list of native trees might be perfect for your land. For gardeners with a more cultivated, constructed garden, there are many recommendations of hardy, handsome, disease and insect-resistant specimens. The Chicago Botanic Garden's Chicagoland Grows® program is dedicated to growing, testing, and eventually introducing into the trade new varieties with ornamental appeal and a strong performance record. Choosing selections from that program is always a good idea. Log on to Illinois' Best Plants on the Garden's website for additional detailed information, including color photographs.
Try to avoid weedy or poorly adapted species that have suffered from overuse and improper use such as buckthorn, silver maple, Norway maple (especially when planted as a street tree), pin oak, some overused spruces and pines, as well as all the crabapple trees that are not resistant to apple scab. Planting and nurturing a beautiful tree is a personal reward. Taking the time and having the patience to educate yourself to do the best job possible benefits not just yourself, but generations to come.