Monday, June 11, 2012

Around the Garden

“How tall will that tree grow?”  That must be the question that nursery and landscape folks hear more than any other. Sometimes it seems as if the answer given is, “How big do you want it to be?”  At the very least, a great many people I talk to are surprised at how large their trees have grown.

Pictured at right is a Kousa dogwood over twenty feet in height, with a canopy over forty feet in diameter. Its owner told me the tree was planted about 50 years ago, when it was pretty much a stick, three feet tall.

This a tree commonly sold as an ornamental, just like its native cousin, the flowering dogwood, along with cherries, crabapples, redbuds, etc.  Most of us think of ornamentals as trees we can tuck into a corner somewhere, often very close to a building. Certainly, you would not expect it to rival a mature beech tree – yet this one does.

What is the reason for this seeming aberration? Well, as one visitor on a recent garden tour said to me, “This is a tree that was planted with enough room.”  Trees, as I may have mentioned (harped on?) in the past, will keep reaching for sunlight as long as they are healthy enough to do so. If they are planted in a spot with plenty of sun and minimal competition, they will gradually fill that spot.

A vanishing sight these days is a sugar maple or a white oak grown in a pasture, probably to give shade to the pastured animals. These trees, sometimes called “wolf trees,” frequently grew to a massive size, while trees of the same species – likely sisters or brothers – grew stunted and narrow in nearby woods. Unlike a vine that can romp through a garden until it finds sunlight, a tree has just two directions in which to grow: sending its leader straight up, or its horizontal branches out as wide as possible. Sometimes, in very shady woods, you will see an oak or a hickory with leaves so large they look tropical; this is the tree’s strategy for maximizing photosynthesis. More sunlight captured by the leaves means more sugar to store for future growth.

I have been lucky enough to manage a small orchard of American chestnuts growing in Middletown, and have watched since they were planted in 2009. The largest of these trees is now a little over six feet tall, with a spread of about five feet. Planted as seeds, they have been fertilized just once, and watered almost entirely by rainfall.  How tall will these trees grow? At two feet a year, they might be twenty feet tall by 2019. But that's still very young for a chestnut -- imagine where they will be if they reach 100 years.

Perhaps a better question to ask before buying a tree is, “How fast will this tree grow?”  Especially before planting it next to your front door, or under your utility wires!

No comments: