Those of us with long driveways often fantasize about having a stately planting of matching driveway trees on both sides, forming a shady “tunnel”. This type of planting is called a colonnade. We’ve all seen them; perfect matching ranks of mature trees marching along the lane leading to the house of our dreams. My favorites are down in Bourbon County, Kentucky, mature pin oaks planted more than a hundred years ago.
Choosing and planting heirloom trees like this takes some planning. Not only must the trees match, but they should be planted at the same time in exactly the same way, and carefully trained so that they continue to match as they mature. Here are a few simple rules:
Pay attention to growing conditions along your driveway. Soil fertility and drainage can vary from one side to the other, or along the drive, which will cause trees to grow unevenly over time. If there are obvious, extreme differences in moisture or soil quality along your driveway, I wouldn’t suggest attempting a colonnade of matching trees.
Start out with quality, matching trees so that they will be from the same seed stock and root stock. Pedigree really matters if you want the trees to match over time. “Limb up” the lower branches so that the bottom limbs on all the trees are at the same height. Driveway trees should be spaced so that when they are fully mature they won’t crowd each other. Spacing should be about 1-1/2 times the mature tree spread; further apart will look skimpy. If you want the trees to form an archway over the drive, they should be the same distance across from each other as their mature spread.
Trees that overhang driveways and streets must be “limbed up” high enough to provide clearance for vehicles. This should be done in stages over several years, particularly if you start with fairly young trees. Spreading trees like Bradford Pear and Norway maple should be avoided because they will eventually block traffic. Upright growers like Cleveland Select pear, Gingko, or pyramidal hornbeam work much better. Shade trees like oak, thornless honeylocust or sugar maple work well too, but should be spaced further apart and further from the roadway. Trees that naturally droop, like pin oak, should be avoided. Red oak, elm or zelkova are better choices since their limbs naturally arch upwards.
For many years, our favorite driveway tree has been Cleveland Select pear. It is easy to limb up to a high crown when young, forms an attractive high oval or cone-shaped crown, and has an alternating branch structure so it won’t split under ice load like Bradford pear. Cleveland Pears are fast growing, very adaptable to poor soils, drought tolerant and disease resistant. They hold their leaves longer than most trees, have showy red fall color and white blooms in spring.
Unfortunately, the state of Ohio has classified all ornamental pears, including Cleveland Select, as invasive plants. Nurseries have stopped planting them, and they can only sell their existing stocks for a few more years.
Years ago we planted 33 matching Cleveland pear along our frontage, and after years of diligent maintenance we now have an impressive line of perfectly matched trees. Our only regret is that we chose ornamental pears instead of longer-lived, sturdier hardwood trees. Ornamental pears are short-lived, softwood fruit trees. If we had it to do over, we would be more patient. Then our stately colonnade would give our great-great grandchildren something to remember us by.
Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are online at www.goodseedfarm.com. For more information call GoodSeed Farm Landscapes at (937) 587-7021.