Let's improve our tree-planting practices!
Most trees planted in Seattle are TOO:
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| Common . . . We need more diversity in planting. Why? Our mild climate allows it (Seattle has more different kinds of trees than any other city); diversity is more interesting to the beholders; it is safer also --as is a diversified investment portfolio. Yet, most tree kinds sold and planted are the equivalent of jade plants in the house, and neutral beige or gray painted houses. If we plant only trees that we know will succeed, we'll become stuck in a rut and never discover new species of merit. Nothing ventured, nothing gained. Plant a wide array of both native and non-native species. Too much reliance on elm planting proved disastrous in the Midwest and New England. Too many maples in Seattle may cause trouble in our future. |
| Thirsty . . . We should plant more trees that need little or no watering once established. Seattle has a dry-summer climate, as does most of western North America. Yet we plant many trees that hail from summer-rainfall regions such as Back East, and Japan. Katsura-tree, for example. We ought not exlude thirsty trees, but they should be used more sparingly --or planted where ground-water is accessible such as near streams. Water is precious. And in gardens of mixed plantings, watering encourages more growth, fungal problems, and weeds --hence more maintenance. Less watering on many species also induces brighter fall color. Aspens are an example. |
| Deeply planted . . . Trees grow better on a slight mound. Go look at large old trees; most are up on a mound and show a swollen base. In contrast, trees planted too deeply show little or no taper at the bottom, are smaller, and often less healthy, while being more prone to rot problems. (Of course, if the goal is a stunted tree that will not grow "too big" then planting a sapling too deep may be a helpful move.) Plant on a slight mound, and your little tree will settle properly. But if you plant "level with the nursery line," it settles too deeply. |
| Close to buildings or wires . . . Trees need space as they grow. It is wondrous that one can legally plant a tree underneath high-voltage power lines, and then not be assessed a pruning fee when Seattle City Light contractors do line clearance. The public picks up the tab. It is sad when even SeaTran permits such trees. The Urban Tree Replacement Program has helped greatly. To be sure, it is our right, as individuals, to plant too close to buildings, wires or whatnot --so long as we prune as needed to keep our trees from causing trouble. But the more sensible approach is to use more small trees, shrubs or vines where there is insufficient room for big trees. Then we get greenery's benefits without the more expensive pruning needs. |
| Root-bound . . . Free roots bring best growth. Most nursery stock has the root mass too tangled or twisted for optimal growth. Some are stunted for life, and are often more likely to blow over. But, as with deeply planted young trees, if our goal is to stunt a tree rather than have it grow exuberantly, this is a good thing. It is good that you can more or less untangle your small tree's roots before you plant it. In similar fashion, young nursery trees that are topped to make an attractive bushy crown --and thus grow too many branches too close together-- can be pruned to secure a stronger branch system. |
| Big- or small-growing for their site . . . We should seek the ideal size for each site. Just like we do when choosing our shoe size. This is problematic insofar as we must admit that a tree can be suitable for some years --before it gets too big. If it is replaced upon gettting awkward, then no problem. What is more deplorable is when there is room for a big tree and little species are already there. We hear much about the desirability to increase the city's leafy canopy. A good way would be to replace small trees in certain places with species that will grow larger. For example, the very old --yet small-- bigleaf and littleleaf linden trees south of the Montlake bridge could be replaced with silver lindens that would not be stunted, not be aphid-infested, and would get enormous. |
| Large when planted . . . Smaller-potted (or burlapped) trees are advantageous: less costly (so more can be bought with a budget); require smaller holes to be planted in (saving labor/time); are easier to handle; are easier to transport; and often if not usually adjust better to their planting without suffering major trauma. Large, container-grown specimens are often doubly- or triply- root-bound. Growers, landscape architects and contractors all make more money on larger sizes. And most clients enjoy more status and gain more satisfaction from big sizes. That is why the practice is prevalent. In some cases, due to vandalism risk, larger trees are almost a necessity. But for most purposes, small stock is not only okay, but better. |
One-dimensional . . . We should seek more than merely beauty. Landscape architects and designers tend to be visual foremost, and so they specify trees that look right. Fair enough, but also we should, in every case possible, consider striving for maximum other benefits. Such as: optimal shading level for the site; food-producing where appropriate; a windbreak role if warranted; air pollution cleansing ability (trees vary); useful wood (when finally cut down); notable wildlife value. This "permaculture" approach is common sense. It just depends on more education. PlantAmnesty is one avenue for helping people learn such things.
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(originally published in PlantAmnesty newsletter Spring 2009, pages 1-3)
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