The Garden Plot
Hosted by Adrian Higgins
Washington Post Garden Editor
Thursday, Nov. 2, 2000; 11 a.m. EST
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."
The transcript follows.
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.
Adrian, I planted my Breck's bulbs about two weeks ago as soon as I received them--this was on the advice of Breck's and what I read in the Post. Unfortunately a few tulips have started coming up already. What can I do? Will they still bloom next spring?
Adrian Higgins: Bulbs grow through the winter, that is normal and the appearance of daffodil tips and tulip stems in the dead of winter is nothing to be alarmed about. However, the fact you can see the top growth only two weeks after planting suggests that you set the tulip bulbs too shallowly. The rule of thumb is that bulbs should be planted two and a half times as deep as they are wide, and that means five to seven inches for standard hybrid tulips. This is really quite deep. You can either lift the bulbs and try again, though this is risky, you may well damage the bulb walls and induce rotting, or simply pile more dirt and mulch on top.
I've recently become enamored with daylilies, and have bought about 40 different varieties in the past 18 months off the internet. How often should I split them? What time of year is best for splitting daylilies?
Adrian Higgins: I am fortunate to have a friend who hybridizes daylilies for a hobby and have been able to buy, as seedlings, his rejects. They are still superb plants and I am struck by how much better cultivars are than the standard tawny lily or common old varieties. If you look around you can find plants with extraordinary color combinations, heavy bud set, and, most impressively, very thick petal substance that stands up well to the hot sun of summer. The best time to lift and divide daylilies is early fall or early spring. It is now rather late because you want fresh root growth before the winter to avoid rotting. If you must do it, I would water in your divisions and then put a heavy mulch over them. Otherwise, wait until early March.
Do you have any ideas for a yard that gets a little sun, has a big maple tree in the middle sucking up all the moisture, and gets a tough licking from a 5 year old boy and a dog?
Ground cover as opposed to grass in bare spots? Gravel? Mulch? Rocks? I am open to anything. Because of my circumstances, I am not looking for perfection, but I am tired of having big dust bowls--big open dirt spots. I have managed to section of small areas near the house for some nice prennials. Unfortunately, I have to keep the boy and the dog!!!!
Adrian Higgins: I would simply lay a few inches of mulch, replenished once or twice a year. (The tree will love it). You can then fill large containers with tropical plants for the warm months, and place them where they will make nifty goal posts.
Adrian, hi, its Ann Donnelly. I'm up here with Dad and have noticed a pine tree seedling which has germinated under the porch. Do you think this will survive in Louisiana? Zone 9, alkaline soil.
Adrian Higgins: Hi, I'm looking at a book that tells me that the white pine doesn't like it warmer than zone 8. If it is a Japanese black pine or Austrian black pine, I imagine it would resent the heat even more. Pines also prefer acid soil. So the brain says no, but the heart is a better guide for gardeners. I would pot it up in a mixture of sand and peat moss and grow it in an area that gets a bit of afternoon shade. If you keep it in a pot you can move it around to a preferred location. Good luck. Hi to Bill.
I planted a climbing rose last year. How far should I cut it back for the winter?
Adrian Higgins: Tie the canes so they don't whip around in the winter wind, and then prune it in February. Keep an eye on the buds on the canes and know that new stems will emerge below the cut, so prune with that in mind.
Hi Adrian, I've still got a ton of tulip, crocus, and iris bulbs to plant. Is it too late, do you think?
Adrian Higgins: Not too late at all, but the soil is really dry and you might want to sprinkle it Friday evening so that it is nice and workable this weekend.
Chevy Chase, Md.:
Can I fertilize a Dawn Redwood now? Or, should I wait until late February? Its a conifer most of the year but it loses its "leaves" in the fall so I was thinking I could fertilize now like I do for the oaks and maples. thanks
Adrian Higgins: If you do, pick one low in nitrogen, certainly not with a lawn fertilizer. The best thing you can do for it is water, water and water. Dawn Redwoods demand moist soil, which is absent now after more than a month without rain.
My hydrangeas are getting too big and blocking the sidewalk. Can they be pruned back hard during the winter?
Adrian Higgins: Wait until after the winter, which may prune the stems back for you. If they have survived the winter (green cambium beneath the bark will tell you which stems are still alive), cut back some of the stems to just above lateral buds. If some stems are blocking the passage, remove them at ground level.
White Plains, Md.:
How long does grass seed last in a bag? (Years? Months?) We have some in the garage and it has been there for a couple of years. Do we threw it away or can we use it? Also, is it to late to plant grass seed?
Adrian Higgins: I have used two year old seed with good results. The germination rate will fall off so you will want to use it at a higher rate than recommended, but do it this weekend. You may have to overseed in the early spring.
My American boxwood have cobweby stuff in their branches and light-colored mottles on their leaves which are also slightly bumpy on the underside. What is the problem? What should I do? Thanks.
Adrian Higgins: You probably have two boxwood pests: spider mites and a leaf miner. This winter, spray with a dormant oil, taking pains to coat the underside as well as the top of each leaf. This should kill overwintering mites and eggs. Spray at a growing season rate next spring to check the first population of mites. For miners, spray against adults when they are on the wing, I think in June, and apply a systemic insecticide to kill the tunneling larvae.
Help! In my enthusiasm I bought about 150 tulips, daffodils and hyacinth bulbs. Now they need to go into the ground. Any suggestions on a good way to do it without breaking my back? Is it too late by the way and can I do it in phases like next couple of weekends??
Adrian Higgins: As I mentioned earlier, soak the soil the day before you are to work it. The most powerful muscles in the body are in the leg, so any tool that requires the leg will be much more efficient than a hand tool. Buy a sturdy (have you noticed how garden writers always counsel to buy a sturdy tool, never a flimsy one?)bulb planter that you step on to use. It looks like a pogo stick with a cylinder on the bottom. Then summon your husband/grown son or other sedentary, muscle-bound man in the vicinity and point to where the holes should go.
Should I dig up my cantas
Adrian Higgins: Cannas I presume. See today's Home section for a feature on how to deal with tender bulbs and plants. You can dig them now or after frost, the choice is yours.
The flower on some of our recently planted mums have turned brown. Should we only cut off the dried flower or should the mums be cut down to the ground?
Adrian Higgins: If all the blooms have faded and you don't like to look at them, you can take hedge shears and give the perennial a haircut. Leave plenty of leaves. Otherwise just remove the ones that have gone over.
We discovered grubs in our lawn last month and treated lawn with a granular 24-hour grub control. When a planted mums in the flower garden I discovered more grubs. How do I treat the grubs? Thank you.
Adrian Higgins: Grubs are back with a vengeance after a respite from last year's drought. The chemical control is with a granular pesticide containing imidocloprid (I think I misspelled that). Alternatively, use a biological control called milky spore, which takes at least three years to be effective but does a better job of long term grub reduction.
I want to plant a lot of miniature daffodils in pots. Do I need to bring the pots inside (basement, garage, house?) or can I leave them outside through winter? If I bring the pots inside, do I need to keep the soil moist?
Adrian Higgins: Most miniature daffodils (paperwhites are an exception) need a chilling period and should be planted outdoors, and yet pots are wont to break in freezing weather. I would work some soil up in a spare bed and bury the pots containing the bulbs. Mulch them well. Starting in mid-January, bring in the pots, forcing the daffodils into precocious bloom to enjoy indoors. Growing bulbs need moisture.
My pansies have plotzed. They are in window boxes on a west-facing balcony. The flowers are limp, and don't grow back, but the actual plants (leaves, etc.) seem okay. What am I doing wrong?
Adrian Higgins: I suspect that you haven't watered them. Pinch off the wilted blooms, make sure the containers drain adequately, and then water like mad. They should rebloom in a few weeks.
Good morning! Do you have any suggestions for replacing a pair of ornamental conifers (trimmed as topiaries) that fell prey to spider mites? I have something tall but danling in mind, but I don't know what it's called. It needs to stay outside all winter in a large concrete pot so as to decorate the side entrance to our house. Thanks!
Adrian Higgins: You don't say how tall, but you could plant some hollies, yews, cryptomerias, even pines. If you like the winter outline of deciduous plants that get big and thin, consider a ginkgo or weeping beech.
My sister, who lives in Warrenton, Virginia, has a lilac. It is the standard native lilac. She has asked me why it is not blooming much anymore. I asked her about sunlight exposure, which is full. I am wondering if maybe pruning the bush would encourage better blooming next season. I know some plants bloom off of "new wood" and was wondering if this is the case for lilacs. Also, any recommendations for fertilizing a lilac.
Thank you for your advice.
Adrian Higgins: Lilacs bloom off old wood so removing stems now will cost you flowers next April and May. It may be getting too much shade from a growing tree, or simply has become old and less floriferous than in youth. If you have the courage, you can remove all the oldest, fattest stems (wait until you see how it blooms in the spring). This will then promote suckering growth which should be thinned somewhat in subsequent Junes. It will take about three years to get back to flowering strength, but will bounce back. Some lilac growers use superphosphate fertilizer to promote blooming and remove faded flower panicles before they set seed.
I have a few questions about my first-ever spring bulb garden that I finally finished planting this week:
I've planted tulips, daffodils, iris, muscari, hyacinths, chionodoxa, dwarf iris, bluebells, lily-of-the-valley, and my lily bulbs from last summer. I laid 1 inch chicken wire across the top of the beds (to keep out a large family of squirrels that lives in Fairlington) and added bark mulch on top (after watering).
What else do I have to do at this point - do I need to keep watering until the first frost or beyond?
Can I just leave the bulbs in the ground for next year (I got the Darwin tulips that are supposed to be fairly reliable perennial performers)?
I tried to interplant early spring, mid spring, late spring, and summer bulbs to ensure a continuous bloom and to camoflage dying foliage. Is this a good idea?
Sorry for the novice questions-
Adrian Higgins: You have done all the right things and your diligence will pay off. Bulbs don't need tremendous amounts of water but yes, keep the soil moist with a weekly soaking, until you have to bring in the hose or it is too cold to schlep a watering can around. After the winter thaw, consider laying a bulb food on top of the mulch. The rain will leach it down to where it is needed.
Can you tell me the right time to trim crepe myrtle and should you trim crepe myrtle?
Adrian Higgins: Wait until after the winter: A hard winter, even in OK, may kill some of the top growth and you would naturally remove the dead wood before anything else. Crape myrtles leaf out late, so be patient. It blooms on new wood so you won't be removing flowering wood. Some varieties want to be multi stemmed shrubs, others trees, don't try and torture one into the other. The best time to shape (as opposed to prune) any plant is when it is young.
Can I still plant winter cover crop in my garden plot? If so, which should I use? I just want to get the extra nutrients and then cut, turn over next Spring.
Adrian Higgins: Winter rye, buckwheat, or crimson clover.
Hi! Can I plant ranunculus bulbs now or do I have to wait until spring in this area? I bought some for the first time from Breck's, and the planting instructions were rather vague. Thanks!
Adrian Higgins: Ranunculus are an early season, spring flowering bulb and should go in now.
Hi! I have a very fickle plant. A hibiscus that I rescued a year ago has been in a cyclical mildly leafy to leafless cycle. It did okay while it was outside, but it didn't entirely fill out like the bushy hibiscus I see other places. Now I have to bring it in for the winter and I know it will have a negative effect, because it is starting to drop leaves like crazy.
How can I stablize this plant? New pot? Add something to the soil? Pruning? Ack!
Adrian Higgins: We had a Q&A question last week in Scott Aker's column on this topic. Hibiscus will lose leaves when you bring it indoors, but the object is to keep the plant alive, not to keep it pretty.
This is Scott's wise counsel: Bring it in to a cool, bright room and water sparingly and don't fertilize (or prune).
Wait until May before putting it back outside. When you do, "thin the weak branches and cut any scraggly growth back to two or three buds. When growth begins, keep the soil evenly moist and fertilize weekly with a liquid fertilizer."
oh I thought I missed you! I am a very novice gardner. I have two Hydranias (sp?)that a friend gave to me which are now a foot tall. Someone told me I need to bring them in for the winter or else they will die is this true and when is the best time to plant them in the garden. Thanks!
Adrian Higgins: Hydrangeas are hardy plants and are best placed outdoors. Florist varieties may not be reliably hardy here. You should plant them in a south or east facing location and mulch well.
Round Hill, Va.:
Happy Garden Clean-up Season! I'm hoping you can help clear up what is a long-going family feud. My husband and I are at opposite ends of the opinion meter on this one. I say it's important to clean-up rotting and bug-eaten debris from the garden as you go along. My husband, on the other hand, regularly chucks rotting fruit and vegetables -- tomatoes are his favorite, the black oozing kind -- in a part of the garden we aren't using, like where we dug up the potatoes or pulled up corn. We have an ongoing problem with earwigs and centipedes, not to mention borers, and this year, for the first time, lots of ants, although they didn't seem to eat much. Who's right? I'm familiar with the principle of composting, but I believe rotting tomatoes, potatoes, squash and beans that aren't fit for human consumption should be cleared from the garden soil. Wha'd' ya think? Thanks for your time!
P.S. -- my husband's fairly reasonable -- he'll either take your word, as the expert, or keep searching until he finds someone who agrees with him!
Adrian Higgins: We are talking about two things here, removal of debris and the operation of a compost pile. The two are complementary. You can and should pick up fallen leaves, fruit and other debris to keep your ornamental and vegetable beds free of disease and pests. Then take all this stuff and dump it in a remote pile. This will rot over the winter and the process will go faster if you chop up the stuff with a lawn mower first and keep the debris moist and turned. Sounds as if you are both right. Now that I've settled that one, I'll try my hand at the Middle East. On second thoughts, I think I'll stay in the garden. Thanks for all your questions, sorry I couldn't get to all of them. Get those hoses running.
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