A primer for suburban tree selection
What is it that sucks up all surrounding food like a vacuum, seems to grow even while you're looking at it, and resists all your best efforts to train it to grow in the direction you'd like to see it take?
Your teenage son? No, it's that Norway maple you bought from the big box store and put in the front parkway. Like watching the neighbor's 10 cats while the neighbors go on a monthlong vacation, it seemed like a good idea at the time.
So, the scrawny sapling you put in is now a 40-foot specimen, its roots have invaded the parkway, the leaves block the morning sun completely so that the cat has had to find another window to take a morning nap in and you are now the proud owner of hundreds and hundreds of maple seedling helicopters that litter your sidewalk, driveway, gutters, and planting beds, and have your otherwise kindly neighbors referring to you as "maplehead."
Again, it seemed like a good idea at the time. That's the thing about planting trees - since the finished product takes years to produce, it's best to try and get it right the first time. It's of little benefit to be 60 years old and think, "Maybe I'll plant an oak." Mature trees take time to grow. Lot's of time.
At the Master Gardener help desk in the Friendship Park Conservatory, those of us staffing the desk to answer gardening questions from the public are often asked what is the best tree to plant in my suburban yard? With the advent of the emerald ash borer and subsequent decline of many suburbs' ash tree population, this is now a very common question.
One of the first things to learn from the ash borer epidemic is the lesson from the ravages of Dutch elm disease that wiped out the stately arches of elms that graced so many suburbs. The lesson is a simple one: plant variety.
Botanists cannot tell you when we will be hit with the next big one, but inevitably, there will be another virus, insect or climate variation like prolonged drought, or climate change that will impact certain trees while leaving others in good shape.
The questions to ask when selecting a new tree are much like those a good reporter would ask when digging into a hot lead for a story: where, why, what, and when?
Taken in order, the first question to ask is where? Where is this tree going to go? Is it going on the parkway? In the middle of the yard? In the front yard? Side yard?
Once the site is determined, then the first winnowing can begin. If the tree is going on the parkway, are there utility lines overhead that will require the tree to be trimmed? Bear in mind that tree trimmers hired by utilities tend to lean toward function, rather than form. Planting an eastern cottonwood that will end up 80 feet or taller may result in a tree that looks as if Mother Nature took a weed whacker to it. Conversely, a hawthorne, or dogwood coming in at half that height could be under the wires and not require any trimming.
The same thought should go into the width of the tree. A tree that will be 20 feet wide at maturity at its base shouldn't be put in a site 5 feet from the side of the house. Will the tree block your view of the sun? Will the branches block your satellite dish? Will the leaves or seeds wreak havoc with your two story gutters?
A line of silver maples in front of a house is an invitation to hours of leaf raking and gutter cleaning. Consider how the tree will impact your lawn. Will the shade be so dense that you won't be able to grow any grass?
The next question is why? Why are you planting a tree?
Do you want beautiful fall foliage to brace yourself against the winter? Pick a sugar maple, oak or sweet gum.
Do you want a harbinger of spring to burst with April bloom? Pick a flowering pear, hawthorn or dog wood.
Do you have a large yard and want to block a view of parking lot lights? Pick a Norway or Colorado spruce, or another of the pine or fir family.
Do you fancy growing some of your own food? Pick a dwarf or semi-dwarf cherry, apple or pear.
Next comes what, and this is the heart of the matter. Just what type of tree do you want? Drive around through some neighborhoods and see what others have planted.
Take a day and visit the Morton Arboretum, or the Chicago Botanic Garden, or some of the suburban parks and forest preserves. Bear in mind that Chicago and the suburbs are generally considered a Zone 5 area, meaning the coldest winter temperatures can hit -20 degrees. There are areas that may be closer to Zone 6, or 10 degrees warmer. We're all familiar with the fact that the city of Chicago is a heat island and minimum winter temperatures will be warmer there. The south side of a brick home will generate a microclimate around it that will tend to be a bit warmer than the north side. Trees such as fruiting trees will fare better if planted in an area that stays warmer in winter.
The University of Illinois extension website, extension.illinois.edu/treeselect/index.cfm, has an extensive list of suitable trees for Illinois and it includes size, growth habit and potential problems. Look under the trees and shrubs heading.
The last question is when, as in when should I plant?
For most trees, spring planting is recommended; however, fall planting provided the tree is adequately watered and planted prior to a hard freeze will generally also yield satisfactory results.
Look for good stock that has been properly maintained. A tree plucked out of a nursery yard and then left to bake on an asphalt temporary garden lot may not have a high likelihood of long-term survival.
Look for a specimen that is not root bound, that is, the tree is in a plastic pot and the roots have grown in a circle.
Your site and your preferences will dictate the species and variety of tree that will work best for you and give you the optimum pleasure for the cost and effort of planting one.
Just remember where, why, what, and when and that a tree is an investment in time, money, and effort that can yield big dividends in memories and beauty.
• Provided by Master gardeners through the Master Gardener Answer Desk, Friendship Park Conservatory, Des Plaines. Call (847) 298-3502 or email northcookmg@gmail.com.