Green Scene

Keeping Temperamental Christmas Roses Happy

The white bracts of kousa dogwoods hold for as long as six weeks.
The white bracts of kousa dogwoods hold for as long as six weeks. (By Sandra Leavitt Lerner For The Washington Post)
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By Joel M. Lerner
Saturday, February 21, 2009

It's time to answer some more gardening questions.

Q: I bought some gorgeous hellebores (Helleborus niger) that were blooming profusely in six-inch pots. The ones in my garden are frozen. How should I maintain the new ones until it's safe to plant outdoors? I have grow lights where my double impatiens is happily blooming. -- Marilyn Cornfeld

A: This hellebore is often called Christmas rose because it flowers early in winter. Growing conditions are seldom perfect for outdoor blooming then. Early spring tends to be their showiest period in the garden. They are root hardy and will grow new shoots in winter when the weather is warm. Then they will freeze and the young leaves will die. Due to this temperamental nature, in winter keep them in the same light and drainage conditions you have provided for your double impatiens, with a cool environment. Plant in a shady garden around Easter.

If you don't have room for them inside, find a protected area outdoors where you can heel them in -- that is, plant them temporarily. Line pots against a shaded house wall with a liberal amount of compost, leaf mold or other mulch to protect and keep root zones from drying out. Lenten rose (H. orientalis) is much hardier, with foliage and flowering characteristics similar to the Christmas rose.

Q: A few weeks ago, you suggested red buckeye or hop hornbeam to replace a tree. What do you think about pond cypress (Taxodium ascendens) or prairie sentinel pond cypress? Are they appealing to wildlife? How do these trees compare in interest to the hardwoods you recommended? -- Joy Kopyto

A: I like pond cypress. It's a deciduous conifer that displays russet red foliage in fall before dropping its needles. This is rare, as most conifers stay green year-round. It grows about 18 feet over 20 years and is tolerant of a wide variety of soils. Often found along stream banks or at higher moist elevations, it's a very tough, dependable native from Virginia south to Florida and Louisiana, and will thrive into New York state, New England and the northern Midwest. Prairie Sentinel is one hybrid that has a tall (60 feet), narrow (10 feet wide) growth habit. Both pond cypresses are slow-growing trees best used as sculptural elements near lawn or with wooded areas as backdrops, designed as vertical and overhead elements bringing your house into the landscape. Several can create a parklike setting. Any native tree will provide a wildlife habitat by creating shelter. Pond cypresses should be available at local garden centers in March, which is a good time to plant them.

Q: My bird of paradise is about three years old and hasn't flowered. We bring it indoors each winter. This year the leaves started to brown and curl. Can I undo the damage? How should I care for the plant? -- John Malone

A: Bird of paradise (Strelitzia reginae) is native to subtropical areas of South Africa, a vastly different environment than ours. If the leaf curls and turns black, it's probably too cold. Avoid temperatures below 50 degrees. Warmer temperatures are more desirable. If leaves curl and stay green, there might be too little light. Dry, brown leaves could indicate too long a period between watering or low humidity. However, plants should dry almost completely between watering or stems might rot. They begin blooming when they're four to five years old and are most ornamental in locations that receive full sun. Protection from wind in hot afternoon exposure is advised.

Locate it indoors near a sunny window, using supplemental lighting during dark winter days. Use a moist, well-drained medium through spring and summer, and allow it to dry somewhat between watering in fall and winter. During the growing season, lightly mist it daily. In winter, mist once or twice a week. Fertilize every other watering with a water-soluble fertilizer such as Jacks or Miracle-Gro. Fertilize once a month in fall and winter. Repot in spring where the plant can remain and grow root-bound. Flowers form when the plant has slightly crowded roots and healthy new growth.

Q: Can I purchase a liquid de-icer for my hand-held sprayer? I plan on applying it to a wooden porch and stairs. Is this a good choice? -- Bill Callahan

A; Liquid de-icers seem to be available only for professional uses. This method of application is most successful for highways, and probably not practical for you to de-ice wooden porches and steps. I recommend a dry granular material. To decrease harm to plants, use magnesium or potassium chloride. If plants are not a consideration, rock salt is a good material to spread before a storm to liquefy the frozen precipitation as it falls and to apply again after shoveling. Use all salting materials sparingly (one to two pounds per 100 square feet), and allow about a half hour to melt the ice.

Q: Can you recommend a hardy, beautiful dogwood for an area about 20 feet from a house and about 20 feet from a Norway maple? -- J. K.

A: The celestial dogwood (Cornus "Rutcan," Constellation) is a beautiful, small, disease-resistant flowering dogwood for part sun or shade. It has an evenly upright habit. Showy in bloom, it flowers about four or five days after the native flowering dogwood, about the same time that it's pushing spring leaves. Fall leaf color is maroon to purple. Another small flowering dogwood for part sun or shade I would choose is the disease-resistant kousa. This dogwood (C. kousa) flowers after it leafs in spring. Its creamy white bracts hold for as long as six weeks, fall foliage is a red to maroon color, and bark has a mottled appearance of tans and browns that is quite noticeable in the winter.

Q: I have a deer problem and am looking for a tree or shrub to plant at the end of my front lawn that will grow tall and have a flower. The garden is in shade and consists of red clay. -- Joyce V. Hoyle

A: The most important step you can take is to prepare the clay soil with about one-third compost before doing any planting. Till about three to four inches of leaf compost into the top eight to 10 inches of red clay. That will create rich, well-drained soil for the following shrubs. The front shade garden is a natural for viburnums. Semi-evergreen Alleghany viburnum (V. x rhytidophylloides) has large (three to four inch) leaves that offer good screening, flowers in late spring and berries in fall and winter. Mature size is about 12 to 15 feet tall by 8 to 10 feet wide. A fully evergreen viburnum that performs admirably for us in shade and protected sun in the Washington region is Chindo (V. awabuki "Chindo"), growing 15 to 20 feet high and 10 to 12 feet wide in three to five years. It does not flower in this region. We have planted them for many clients in this area and have never seen the deer eat them, but there are no guarantees.

Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site, http://www.gardenlerner.com.


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