Green Scene

Green scene: It's springtime, and readers have a lot of questions

Even if azaleas were flattened in a snowstorm, robust varieties will be full in a few years.
Even if azaleas were flattened in a snowstorm, robust varieties will be full in a few years. (Sandra Leavitt Lerner/for The Washington Post)
By Joel M. Lerner
Saturday, April 3, 2010

Trees, shrubs and herbaceous plants are flowering, lawns are growing, plants are leafing out quickly, and the pruning and repair of broken limbs and other damage from February's blizzards should be almost finished. As reader questions suggest, it's time to renew lawns, plant shrubs and control garden pests.

Q: My young, two-story-high magnolia bent over in each snowstorm this winter. Each time I shook off the snow. After December's storm it rose back to its full height, but after the two February blizzards it remained partially bent over. Can I expect it to become straight again? Can it be propped up until it grows straight, or is this the end?

A: It doesn't sound like the end, since you didn't indicate there are brown leaves on the tree. If foliage is green and wood is bent but not broken, the tree will straighten if it's in good sun. If branches broke, the remainder should rise with spring growth.

To prop branches, use three 24-inch-long, 2-inch-square stakes driven into the soil at a 45-degree angle. Place them equidistant around the tree. Thread some 8-to-12-gauge wire through a length of garden hose (which keeps the wire from cutting into the bark), and loop the protected wire around the trunk. Wrap the ends of the wire around a stake and pull them until the tree appears to be vertical. Leave the tree cinched no longer than six months. When you remove the wire and stakes, the tree should remain straight.

Q: Do you have suggestions about reworking azaleas that have broken branches or other damage? How do I know when to replace them?

A: Azaleas will renew dependably. Prune cracked branches and any stems and branches that were stripped by ice and snow but are still partially attached to trunks. This will encourage new growth. Evaluate plants after pruning. Even if there are only roots with no wood left, azaleas can renew. If there are stems, shape them by lowering healthy ones and heading back to viable foliage. Selectively prune so shrubs are a fairly even height with one another. In July, by natural selection, azaleas will decide which ones will renew and which might not. If they were robust, they will become so again, in a few years. Cleanout pruning and patience is key. Then decide if the damage is so bad that the plants need to be replaced.

Q: Where can I get corn gluten weed preventer?

A: Cornmeal (gluten) weed preventer is available at most garden centers. Apply it before crabgrass germinates -- by the time forsythia is in full bloom. Be sure to follow application instructions on the label.

Q: I planted a blueberry bush too close to the house. It's about two feet tall. When can I transplant it?

A: Your blueberry bush (Vaccinium corymbosum) is a shrub regardless of species. Some grow as groundcovers, others grow six feet tall. It needs full sun and should be protected from birds when berries are ripening. Transplant now, before growth begins.

Q: During the last snowstorm, our evergreen fell down. We have a small area. Could you please provide some suggestions for plants native to the D.C. area and best time to plant?

A: Try filling the bare space with a native shrub like viburnum offering flowers, berries, fall color and bird-attracting qualities.

Research the characteristics of the following native species and you will find a match for your space: mapleleaf viburnum (V. acerifolium), blackhaw (V. prunifolium), American cranberrybush (V. opulus var. americanum), witherod (V. nudum var. cassinoides), and arrowwood (V. dentatum). Flowering and berry set will be most prolific if shrubs are planted in full sun or in very light shade. Viburnums can be selectively pruned to fit spaces. Plant as soon as you can find one that fits your needs.

Q: Our 25-year-old, 20-to-30-foot-tall Colorado blue spruce and 15-year-old, 20-foot-tall Italian stone pine bent nearly to the ground in the February snows. I removed as much snow as I could from the spruce. It has righted itself about two-thirds of the way. The stone pine is still leaning about 15 degrees. The trees do not receive much sunlight. They appear to be firmly rooted. In the past two weeks their return back to vertical seems to have halted. Is there anything we should do to help them? Also, our 25-year-old, 30-foot-tall hemlock had six feet break off the top of its trunk. Will it survive?

A: The Colorado blue spruce and Italian stone pine will regain their prior form unless they suffered many broken branches. Time will tell as they grow or turn brown. The shaded sides of trees will recover more slowly than the sunny sides. Follow directions given in the first question to help straighten leaning trees. Spruces and pines, as well as most other trees, tend to have a more open growth habit on the shady side of the tree, usually growing toward the sun. The hemlock is different. There is no need to stake it because of storm damage. The branches that have needles will continue to grow as long as they are healthy trees. You might want to cut the damaged area with a smooth angled cut so water will not remain that could decay splintered wood.

Joel M. Lerner is president of Environmental Design in Capitol View Park.

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