The Garden Plot
Hosted by Adrian Higgins
Washington Post Garden Editor
Thursday, Sept. 28, 2000; 11 a.m. EDT
Adrian Higgins will be online Thursday to field your questions and comments concerning gardening and horticulture.
Got a chronic case of green thumb? Like getting your hands dirty? Adrian Higgins, garden editor for The Post's Home section, is here to help. Higgins is a firm believer in "tough plants for tough times" -- the varieties that combine good looks with stiff resistance to disease and pests. He currently rules over a garden filled with spring bulbs, daffodils, ornamental onions, perennials, asters, yarrows, hostas and day lilies. Higgins, an avid organic gardener who believes chemicals are a last resort, also tends his own herb and vegetable gardens where he grows peas, garlic onions, lettuce, rhubarbs, radishes, carrots and more.
Higgins is the author of two books, "The Secret Gardens of Georgetown: Behind the Walls of Washington's Most Historic Neighborhood" and "The Washington Post Garden Book: The Ultimate Guide to Gardening in Greater Washington and the Mid-Atlantic Region."
Below is a transcript of today's discussion.
Editor's Note: Washingtonpost.com moderators retain editorial control over Live Online discussions and choose the most relevant questions for guests and hosts; guests and hosts can decline to answer questions.
My wife and I live on a pie shaped lot on a cul-de-sac. The rear of the lot is wide and quickly slopes down a hill to parkland and tall trees. It has southwestern exposure and full sun (no trees). We are considering a stone terrace and planting beds so we won't have to mow the lawn. Do you have any suggestions? What types of plants and trees would do well in this situation?
Adrian Higgins: As with most landscapes, the best planting schemes are the simplest and boldest. I would use a mixture of conifers, a shade tree or two, and several strategically placed ornamental trees as building blocks, filling in the spaces beneath them with small and medium sized shrubs. As the larger trees grow, the site will become shadier, so plan and adjust your plantings to take that into account. Since you will be looking down on plants, select ones with ornament seen best from above, kousa dogwoods, mahonia, vitex, come to mind. Make sure you have a broad and appealing path into the hillside so that you can go down into it and enjoy your plantings. The beauty of terraced beds is that you can create your own soil and drainage conditions, you don't have to cope with waterlogged hardpan. Hence your plant choices are greatly expanded.
I live in a basement apt., but would still like to have some houseplants around. Do you have any suggestion of plants that require very little natural light, but will still be nice?
Adrian Higgins: Some of the plants that will survive in darker conditions are aspidistra, English ivy, clivia, and various fern species. Go to a garden center or florists and ask what they have that would be suitable for your apartment.
I've just moved into a new (to me) house and started planting. It's my first garden and I don't know that much about plants. I've just planted two crape myrtles (the Victor variety) a lilac (a new variety resistant to powdery mildew) and two camelias. The soil is that great Virginia clay. I loosened it up as best I could, put in about 3" of topsoil all the way around the hole and added some Plant-tone to the soil. What can I do to keep them alive through the winter?
I also have some beautiful (but huge) hydrangeas (oak leaf). Should I prune them and how?
Thanks a lot, I have found your book (The Post one) to be very helpful.
Adrian Higgins: Newly planted shrubs and trees need special care. The first consideration is siting: Is the location sunny/shady enough and will the plants have enough space to grow. The second consideration is soil condition, can the native clay be improved and drainage corrected? Third the roots must be scored or loosened to allow them to grow out into the new soil. Fourth, you must not plant too deeply, causing the root crown to die in wet winter weather, or to shallowly, where the fine feeder roots will dry and die. Then you must water well and regularly until the first hard frost. You could apply some fertilizer formulated for root growth, but don't use a high nitrogen one, which will force tender growth that will be hit by frost. Prune the oakleaf hydrangea in late winter, you can take wood off to just above swelling buds, but don't go overboard, the beauty of this shrub is its large, layered look and people wait years to attain that.
What's the secret to growing successful brussel sprouts? I love the things and grew them quite successfully one year in our community garden plot. Last year's plants were all consumed by worms (cabbage moth?). This year I bought some very healthy looking plants from Johnson's and planted. All but one have leaves bitten to shreds. Don't see any worms this time though so can't be sure what's "bugging" them.
Adrian Higgins: The caterpillar of the cabbage white is a green hue that matches that of the plant: it's very difficult to detect one. There are also leaf and bud joints where they hide. I would apply an organic insectide or Bt and then police the plants carefully and regularly to ensure they remain bug free. With cabbages, it's fairly easy to cover them with a landscape fabric that will keep the butterflies from laying eggs, but it's more difficult with brussels, which are more upright.
If I apply pre-emergence crab grass killer to my vegetable garden in the spring, will it adversely affect the vegetables?
Adrian Higgins: Possibly, I wouldn't do it. The preemergent is meant for turf, to prevent crab grass seeds from germinating. In your vegetable garden, pull all existing crabgrass plants now and then turn the soil in February or March, adding compost, in preparation for the growing season ahead. This will disrupt the seeds of crabgrass. If you see any seedlings emerge in the spring, pull them as you patrol your garden.
I live in a rented group house in DC (Glover Pk).
Needless to say, our postage stamp yard is a mess. I was thinking about planting some ground cover (ivy or pachysandra) as I'm tired of mowing weeds and crabgrass.
Any procedural suggestions? Should I use some weed killer before planting or is uprooting sufficient? Spacing of plants to ensure spreading and growth?
Adrian Higgins: Now is an excellent time to do this. You could use Roundup and wait a week or two and then plant your ground covers, but since your space is small, I would buy or borrow a very good brand of garden fork and turn the entire patch. Separate the earth from the weeds, add some bags of humus, and turn the soil once more. Rake it smooth, and then plant your groundcovers. Both suggestions are fine but a little pedestrian. Consider liriope or even a low growing shrub such as Japanese garden juniper or barberry 'Crimson Pygmy' Space according to label intructions. The junipers, for example, should not be any closer than three feet apart, while the liriope would be spaced 12-18 inches apart.
I have a shade perennial garden with hostas, phlox, bleeding heart, hydrageas, and a rhododendron. What do I need to do in terms of maintenance for winter so that they will be healthy in the spring? I've already put a fresh coat of cedar mulch over the garden about a month or so ago. Do I need to cut back the hyrdrangeas? They're still green-leaved, just without flowers now.
Also, should I be planting any bulbs now for flowering in the spring? If so, can you suggest any flowering bulbs that will do O.K. in the shade? Thanks!
Adrian Higgins: The hostas, phlox and bleeding heart will die back, simply remove the spent top growth this fall, for a clean start next spring. The best time to prune a hydrangea is in the early spring, after you see which of the canes survived the winter. You may need to thin out the tangle, but leave enough emerging buds to provide a flower show next June. Spray the rhododendron in November with an anti-desiccant such as Wilt-Pruf, and water it well between then and now. Some bulbs do better in shaded conditions than others, I have had luck with miniature varieties and species of daffodils as well as chionodoxa and smaller fritillaries.
Tina in Falls Church:
Rhis year I planted three "pennisetum rubrum" plants. They have done pretty well in a northwest exposure. They have beautiful burgundy leaves and pink foxtails. A neighbor has told me they will not survive the winter here. Is there something I can do to try to winter over these plants? Dig them up, cut to the ground and store somewhere? I really don't have a place inside to let them continue to grow since they are so tall. Thanks
Adrian Higgins: Most people treat them as annuals and simple discard them. I suppose you could try and overwinter the plant in an unheated shed or garage, occasionally watering it. I don't think it would do well in an indoor, heated room. Alternatively, take the seeds and start them in styrofoam cups under lights.
I have a poinsettia, currently in a north window, that seems to be thriving, though it's a bit leggy. What care does it need to "flower" this winter?
Adrian Higgins: Divine intervention. Only joking. It needs total nighttime darkness, a stray light inside the home or out would prevent its bracts from coloring up. Greenhouse raised plants are disbudded several times and treated with a virus, I believe, to promote bushy shape. You may have the leggiest flowering poinsettia on the block.
Lawng Island, N.Y.:
Can I really eat the berries off of my Kouza tree? What should they taste like?
Adrian Higgins: I have never heard of people eating them. I don't think they are berries, they are seed pods. Either way, leave them for the birds.
I bought a hibiscus plant at a local home improvement store, where the garden department manager assured me that it was a variety that would do well in the outdoors year-round. I have put them in a sunny location that gets some protection from weather (the tall fence nearby acts as a sort of windbreak).
What sorts of precautions would you recommend I take to ensure that the hibiscus will be okay through the winter? I am considering building a chicken-wire collar around the plant, and filling the collar with compost and grass clippings, in an effort to insulate it a little bit, but am unsure as to what time of year would be a good time to set that up -- I don't want to set it up too early (and not give the plant enough sunlight), but setting it up too late could have dire consequences.
Adrian Higgins: If it is a tropical hibiscus, typically with large red flowers and prominent pistils and deep green, glossy leaves, then it won't overwinter outdoors in our climate. The only hardy version I know is the swamp mallow or hardy hibiscus, which is a native perennial that demands moist conditions and then flowers in late summer. If it is that type, you won't need to go to the trouble of protecting it this winter. If it is the other type, find a cool, bright room in the house for it to spend its winter.
I am planning a white flower garden for our backyard, so that we can still see the flowers late into the evening. The backyard varies from partial sun to full shade, and the soil is mostly clay (although I'm doing what I can to amend it).
What sorts of plants would you recommend for a "white garden" that would do well in this area under these shady circumstances? (Not restricting to just white flowers of course ... any advice you may have on plants with light-colored foliage would be great too!)
Adrian Higgins: Various hydrangeas and viburnums, azaleas, dogwoods, cherry-laurel, Solomon's seal, hostas, sweet woodruff, lily of the valley, trilliums, white blooming scillas, Allium moly, lamiums, and various hellebore varieties. Japanese painted ferns and foam flowers would be good too.
I have an indoor flower box, which the builders of the my home (in their infinite wisdom), constructed in wood with no drainage outlet. Watering the plants means mopping up water that seeps through the walls into the basement.
So basically, it's a box with dirt. It sits in a prominent place in my home, at the curve on a winding staircase near a cathedral ceiling window.
What can I do to waterproof this box and grow plants or flowers, or should I consider another use for it?
Adrian Higgins: Surely there is a plastic liner you could buy to put in it, or a fancy copper one for the outside. It does sound like a good place for a planter, with plenty of natural light.
thanks for less pedestrian suggestions on ground cover.
I looked up liriope on the Internet: It is both a ground cover and a kind of jellyfish (Liriope tetraphylla Phylum Cnidaria)!
Jellyfish in my garden - neat, huh?
Adrian Higgins: Would look neat in a hurricane. All wobbly.
Usually, our tomatoes are the best in the world. We live in a karst region alongside Lost River. This summer, they had blossom-end rot. How should we prepare the soil this fall so this won't be repeated. I know it probably is due to weather, but what must we do? We had too much foliage around them I know, for we had zinnias on one side and cucumber on the other side. Broccoli, then corn up above them. Could be due to over-crowding. Broccoli was excellent, we harvested a long time. Usually in hot weather this plant has worms, but not this year, I wonder if these hybrid plants contained something the tomatoes didn't like.
Adrian Higgins: Blossom end rot is usually caused by uneven watering and a lack of calcium in the soil. Next year, make sure you work limestone into the soil and keep the soil evenly moist.
Do you know what the diffrence in purple African basil and normal basil is? Can I start normal basil inside for a winter plant?
Adrian Higgins: Purple basil is another variety. It is possible to grow and keep basil indoors over the winter. Take a cutting and place it in a vase of water with some charcoal pieces at the bottom. The basil will root in the water and grow through the winter, given enough light. Snip off leaves as you need them.
I recently bought some American holly plants that had some fungus/discoloration on parts of the bark. When I asked the guy at the nursery he said that it was normal and the discolored parts were that way becuase they didn't get enough sunlight (like other parts of the bark did). The discoloration/fungus is dark and sort of looks speckled (not a solid color).
Should I be worried or is this normal?
Adrian Higgins: American hollies show this mottling when young. As long as the leaves remain a healthy green, no worries. Some leaves will turn yellow next spring, but that is a normal leaf dropping exercise.
Is there any way to protected outdoor container plants? I have several plants in LARGE pots on the deck (hard to move indoors). Is there a way to insulate the containers to prevent root damage?
Adrian Higgins: You don't say what's in the pots. If they are tender plants such as lantana and impatiens, you would want to lift and discard them anyway. It is a false economy to try to keep them through the winter when fresh, disease free plants are grown professionally for the spring annual market. The same goes for soil. Old soil is nutrionally spent, compacted and may have plant pathogens. Empty the pots, brush or scrub them clean and store them indoors.
If they are hardy plants, you may need to insulate the roots with some sort of protection, such as bubble wrap or foam sheets. Generally, the smaller the pot the greater the danger of root or bulb freeze.
If you have tender bulbs worth keeping, such as dahlias, cannas, colocasias, and caladiums, wait for the frost to kill off the top growth then lift the bulbs, spray them with a fungicide, let them dry in the sun on a warm November day, and then bring them indoors for the winter.
Thank you for all your questions today. Now is a great time to get out into the garden for planting, dividing, and cleaning up material before the leaves drop and become the overwhelming chore.
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