by Lindsay Bond Totten
Scripps Howard News Service
Some answers to recently asked questions:
Q: When is the best time to divide re-blooming irises?
A: Most re-blooming irises are of the bearded variety, so they grow from rhizomes rather than from bulbs or fibrous roots. The best time to lift and split the rhizomes is right after the spring blooming period but before the rhizomes have resumed growth for fall.
About four to six weeks after the first set of flowers has faded, cut back the foliage, dig the roots and split the rhizomes into smaller pieces, each with two or three growing points. Discard the oldest portions--they won't bloom again. Reset the divisions about 12 to 18 inches apart and water them well. Growth should resume within a few weeks. Vigorous varieties may bloom that first fall; others will wait till spring.
Q: I'm having a terrible time with grassy weeds in my perennial border. Hand weeding seems to encourage rather than eliminate them. Is there something that will help?
A: Sounds as if you're struggling with perennials grasses, which spread by means of long, persistent underground roots. Unless you get the entire root, new shoots will continue to appear, up to several feet away from where the original weed was pulled.
A non-selective herbicide, such as Roundup, can be used if you're very careful. Using a piece of cardboard to shield the leaves of desirable plants, paint or spray a bit of the solution onto the weeds. Let it dry before removing the cardboard. Also, consider an application of Ortho's Grass-B-Gon, a product that targets grassy weeds in broadleaf planting. Be sure to read the label carefully to make sure the product is safe to use around the types of plants you're growing.
Q: I'm not having any luck growing cilantro. The leaves just don't have much taste. Am I growing the wrong variety?
A: Probably not; you may just be harvesting the herb incorrectly. Pick only the leaves from the very top of the plant and discard the rest. Sow seeds frequently for a continuous supply of cilantro in hot weather.
Q: Is there a way to get more flowers from the clematis vine on my arbor? I get a beautiful flush of flowers in late spring, but very few blooms after that.
A: Careful pruning can coax more blossoms from a clematis vine. Only you can decide whether it's worth the time and trouble. Here's how:
Instead of heavily pruning the entire top once a year, prune just a half to a third of the stems at one time. As soon as the blossoms fade on one stem, cut it back. This will encourage re-growth and more blooms on that stem later in the season.
Overall, the vine will produce about the same number of blooms as before, but they'll be spaced out, giving the appearance that your clematis is in bloom for a long period of time.
Obviously, this pruning technique represents a labor of love. If a busy schedule prevents you from giving the vine this much attention, consider planting another clematis that blooms at a different time of year. (Clematis jackmanii blooms in midsummer and should complement a spring bloomer nicely.) Or, plant an annual vine on the arbor next to the clematis for summer and fall color.
Q: It's late, but I'd still like to plant a few annuals. Is there any point in buying the "leftovers" available at my local greenhouse? The plants don't look great.
A: Flowers should be inexpensive now, with "end of the season" bargains available. Why not give it a try? When you get the plants home, cut them back hard. Remove all the flowers and much of the leggy growth. Before planting them into well-prepared soil, pull the roots apart and gently trim them. Feed plants immediately with soluble fertilizer to give them a quick start and again in two weeks, followed by a slow-release fertilizer. Keep them well-watered, and in a couple of weeks you could have quite a show!
Q: I grow climbing roses on decorative metal rose towers. Some bloom well, but others don't. Why?
A: It may be your choice of plants. Large vigorous varieties, such as "William Baffin," are not well-suited to rose towers as those with shorter canes, like "Climbing Sally Holmes." Since climbers bloom best at the ends of lateral branches, you may be pruning off the flower buds when training them to the tower.
(Lindsay Bond Totten, a horticulturist, writes about gardening for Scripps Howard News Service.)
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