May 23, 2008

A Few Good Trees

Choosing good trees is an important - but sometimes difficult - part of landscaping. Unlike smaller plants, trees are difficult (and often expensive) to move or remove once established. Their large size means that any problems (ie weak wood, insect infestations, messy fruit or seed pods) eventually become big problems. One common mistake that homeowners make is planting a cute little tree right next to their home or in another unsuitable position. It's hard to believe that every giant tree began life as a tiny plant. Those little trees keep growing, and growing, and growing . . . so give them the space they'll need!
For a fairly quick-growing but sturdy shade tree, maples (Acer) are a good choice. Be sure to avoid 'Norway' maples, which have weak branches that break easily in wind/snow/ice storms. 'October Glory' and many others have excellent fall color.
With yards getting smaller these days, most of us don't need huge shade trees (such as maples) that take over our neighbors' sky and require a lot of cleanup in the fall.

A wonderful medium-sized tree is a 'Shademaster' honey locust (Gleditsia triacanthos 'Shademaster'). Instead of reaching 80-100 feet in size, honey locusts grow to about 25-30 feet wide and 35-45 feet tall. Their small leaves make less mess in the fall, and though some types produce seed pods, 'Shademaster' is podless. Their branches have a lovely form even in winter, and the shade they produce in summer isn't so heavy that it kills the grass underneath. 'Sunburst' honey locusts are also podless and their new leaves are yellow. This can look a little strange on a young tree, but mature trees are lovely with "bursts" of yellow leaves on the tips of branches set against the green leaves on the rest of the tree.

My favorite ornamental small tree is a dogwood (Cornus florida), but these trees require A LOT of water. I inherited one from our home's previous owners that is planted in a sunny and rather hot spot. In addition to being watered by the sprinklers every other day, it needs to be soaked deeply with the hose once or twice a week during July & August. I do it gladly, however, because I adore the beautiful pink flowers that appear in May (there are also white-flowered forms). In my fairly dry climate, dogwoods do best when shaded from the hot afternoon sun (ie when planted on the east side of the house).

Other nice spring-flowering trees for zone 5 climates are 'Spring Snow' crabapples (Malus) with white flowers and a columnar-shaped crown, and 'Kwanzan' cherries (Prunus) with pink flowers and a spreading, vase-shaped crown.

The crown is the part of the tree formed by the branches. Both of these trees are fruitless, which means less mess in the fall.
And now a few trees to avoid . . . 'Bradford' pears are lovely trees but their branches break easily. A note about flowering pears - these trees have glossy green leaves and pretty white flowers in the spring, but the flowers kind of stink! Poplars and willows grow quickly but also have a problem with weak wood that leads to breaking branches. Even if a large branch doesn't come crashing down in a windstorm, many twigs will be blown off and make a big mess. Quaking aspens are a popular choice in my neighborhood, but these trees send up dozens (even hundreds?) of "babies" from their roots. If you don't want an ever-growing thicket of aspens, you have to continually pull up the baby trees, which is a pain in the rear. At one nursery where I worked, we sold "Swedish" aspens which weren't supposed to send up as many baby trees. I'm not sure of the latin name for that one. But if I had my heart set on aspens, I'd do a bit of research to find some "Swedish" ones. Finally, blue spruces and other large coniferous evergreens are usually too big for a typical suburban yard. They grow to 25 feet wide at the base, which takes up most of the yard and is difficult to balance visually.