The Garden Plot

Adrian Higgins (The Washington Post)

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."

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.

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washingtonpost.com: Adrian should be with us momentarily.

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washingtonpost.com: Adrian is here and scanning today's questions. Stay tuned.

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Alexandria, Va.: Novice gardener here who bought a house with an overgrown white rock garden (about 8 x 10) in the front (eastern exposure, lots of sun). We've started pulling out the rocks, the disintegrating black tarp, and grass with the hopes of planting a small vegetable garden there next spring.

I'm afraid that once it's cleared, grass and weeds will overtake it again. Should I throw mulch or something on to keep it clear?

And is a vegetable garden a good idea? I know that they can sometimes look "ugly" during certain seasons. The spot is right at the front of the house but I thought I should take advanatage of the sun.

Any advice is appreciated!

Adrian Higgins: There are ways of making vegetable gardens pretty, but you have to work at it. Use paths, flowers and trellising to keep your sprawling summer veggies, including tomatoes, looking tidy. Why can't you do the vegetable garden now? This isn't a big area, and if you don't get it cleared and replenished with soil for the May planting season, you can certainly plant fall crops beginning in August. I wouldn't wait a whole year, the area will be overrun with weeds.

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Arlington, Va.: In finishing off my garden pond, I pulled back some of the rubber pond liner and noticed TONS of cicada holes under the liner. I don't want to block in the little guys, but its too late.

My concern now is -- will they chew through the pond liner in their fight for the light?

Adrian Higgins: If you are an insect lover, certainly pull the barrier. They will not be able to chew through it.

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Gatihersburg, Md.: Hey Adrian, thanks for the chats!

I put in a perennial garden two years ago (this is it's third season). The garden is doing great. However, I put in a ground cover called creeping Jenny on one side of the garden under a tree. This year, the creeping Jenny is spreading, thinly, in amongst my hostas, and daylilies and ferns on the other side of the garden. Also, it used to be very full and compact in its original area, but now it is thinner. Is this to do with it's spreading? Should I trim it back to encourage thickness? Should I let it spread amongst the other plants or keep in it its own area?

I really like the plant a lot and would like to have it look like it did before.

Thanks so much!

Adrian Higgins: Creeping jenny loves moist soil and given rich and moist conditions will spread with abandon to the point that it will become invasive and you will have to dig it out at the margins. IN full sun it glows an acid green and is a fabulous ground cover if you can provide the soil conditions and are willing to keep it in check. It doesn't like poor soil or drought.

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London, U.K. & Alexandria, Va.: I live in London but have for the past few years been trying -- by mail order, e-mail and annual visits -- to help my parents in Alexandria develop their garden.

One thing that grows so well here in the U.K. are various types of hardy fuchsias, and I think my folks would really like some in Alexandria, but when we tried a magellanica it just rotted off within the first year.

Is there a variety that does well in Northern Virginia, or are the summers just too hot and humid?

Adrian Higgins: I know of no hardy or tender fuchsia that will grow well in the heat and humidity of Virginia.

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South Riding, Va.: I think I made a big mistake with a climbing rose that could cost me my marriage! Last year, its first full season, it was beautiful and climbed 20 feet high with tons of roses. In February, I was out trimming back our other roses and mistakenly chopped the climbing rose to the bone (about one foot off the ground).

My wife almost threw me out of the house. I told her it would be fine, but I was wrong. While the other roses have started to grow, the climbing rose has not budged.

Help me save my mariage... How can I save it and how should we keep it under control in the future?

Regards,
In the dog house

Adrian Higgins: It will not bloom again until the summer of next year, assuming you don't cut it back hard. Climbers flower off canes that are one year old.

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Bethesda, Md.: I have a very precious lilac bush that probably needs trimming. How and when do I do this? It is presently flowering, but not very lush.

Adrian Higgins: Give it sunlight and prune out the faded flowers. If it still doesn't bloom, cut it to the ground and wait two or three years. If it doesn't bloom then, find another shrub.

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Silver Spring, Md.: Should one even contimplate planting new grape vines this year with the cicada invasion? How much damamge would they do to a new plant like that?

Adrian Higgins: I would plant them. It will take a couple of years for the vines to reach flowers and fruiting size, so planting them now won't harm them even if they get some damage from cicadas.

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Harrisburg, Pa.: Why do you suppose our last year's luxuriant patch of bee balm has not appeared this year?

Adrian Higgins: Bee balm is not a particularly long lived perennial, you may need to plant some more.

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Annandale, Va.: Last summer I planted five hellebores in an area of my yard where azaleas, hostas, ferns, astible, and bleeding heart do well. The hellebores are doing fine in terms of leaf growth, but they did not flower this year. Should I be concerned? They are planted under an evergreen tree -- was this a bad idea?

Adrian Higgins: No, hellebores will take shade, even dry shade, but it does take a year or two for them to get established. Care for them this season and you will start to see blooms next winter into spring. Be careful in removing the old foliage in winter that you don't damage the emerging growth from the crown.

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Charlotte, N.C.: We're having sod put down in our back yard today. I don't know if we're out of cicada territory here, but if we're still in it, does the sod prevent the cicada from emerging? I'm not sure I want to kill them; hardly seems fair after a 17-year wait. On a related note, if they emerge anyway, will they destroy my newly laid sod?

Adrian Higgins: I don't think the sod would prevent them, though I believe you are too far south for the Brood X eruption about to happen here. We could send you some if you want.

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Alexandria, Va.: We just bought a home in Alexandria with raised vegetable garden beds. However, it looks like the 2x6's used to line the beds are pressure-treated. Is this dangerous? I know that the soil was replaced a few years ago, but the beds are narrow -- about two feet -- so there's no way to plant "away from" the edge...

Adrian Higgins: The good news is that the arsenic in these timbers doesn't tend to leach out. Ideally you would replace them,and you may not want to plant a long standing crop like potatoes or carrots, but I think you'll be all right for some leafy veggies.

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Springfield, Va.: Hi Adrian, I am having difficulty growing grass in the area around a Norway Maple in my front yard. Is there anything that I can do plantwise, or can I put some mulch around it? Though in the past I believe you have recommended not to put mulch down around trees.

Adrian Higgins: Mulch in the root zone of a tree is really good for the tree. It's mulch against the trunk that is the harmful practice. It is not possible to grow grass (or much else) under Norway maples. They are considered inferior plants these days and you may want to replace it with a fresh tree.

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Washington, D.C.: Help -- my clematis is growing beautifully, but it flowered only meagerly last year and doesn't show signs of a better season in 2004. It is a type C variety in a semi-shady location. I pruned it back quite low to the ground in February. Should I cut it back again to encourage flowering? Food ideas? Thanks.

Adrian Higgins: Type C, that sounds like me. I'm not sure what variety it is or hence its pruning regimen. It may be sulking from the shade and they are not readily moved. If it responds vigorously from your pruning, then next winter cut it back more gently. You will know in 2005 whether it's a keeper.

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Baltimore, Md.: I live in Federal Hill and like most city dwellers have to be aware of the rat problem. My back courtyard is cemented, but I really want to get planters and create more of a garden space. What can I do to discourage the rats from burrowing in the planters? Are there certain types of plants I should get/avoid? Thanks for you help!

Adrian Higgins: I'm told rats can chew through metal but I refuse to believe it. I think I would plant containers with lots of gravel at the bottom, and line the edges with hardware cloth. Perhaps not a good year then to grow edible plants in containers for you. Also avoid the sweet potato vine, which I hear can attract vermin. Don't keep a compost pile until the rat problem is solved, and get some rat traps.

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Alexandria, Va.: Adrian -- I know you will be inundated with questions about Cicadas, and I read the article today in The Post. All very informative, but I'm still wondering about a lot of fragile trees in my yard. I have five Japanese maples that are about six years old. Do I need to worry about them? I also have a young (about four years old) lilac tree and several young (three-year-old) forsythia bushes. I also have several 5-6-year-old trees that I can't identify, but they are somewhat fragile. Should I try netting, or just hope for the best?

Thanks.

Adrian Higgins: If the maples are upright varieties, I wouldn't bother. If they are weeping versions whose branch structure is very important aesthestically, I would cover them in netting, I think. Leave the lilac and forsythia alone. Cut out any damaged branches in late summer.

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Annandale, Va.: What is the difference (in appearance, and in their effect on trees, etc.) between the 17-year cicadas and the ones we see and hear every summer around here?

Adrian Higgins: The regular ones, called dog day cicadas, are slightly larger, and don't have the red eyes or orange wing edges of the 17-year cicada.

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Rockville, Md.: We have a known bunny and mouse in our yard... however, we would like to grow a small veggie garden to show the kids about plants, etc...what is the best way, yet not expensive, to protect a new garden from our garden friends?

Adrian Higgins: The mouse won't be a problem, but rabbits can burrow down two or three feet, so I would dig a trench all the way around the garden that is two feet deep and stick in a wire fence that is, say, five feet in height, with three feet sticking above ground, if that makes sense.

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Kensington, Md.: We have a 40+ oak tree that is covered in vines. We have cut the major roots away to try and kill the vines, how do you suggest I take down the dying vines, or will they come down on their own over time? And how do I keep new vines from growing/spreading?
Thanks

Adrian Higgins: Sever the vines and daub the cuts with glyphosate weed killer. If they show signs of resprouting, repeat the process. In time, the vines will die and you can rip them down. Watch out for poison ivy.

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Washington, D.C.: About 18 months ago I planted a climbing hydrangea next to a fence in a semi-shady (in the summer it is mostly shady) spot in our garden. In the summer it gets lovely lush green leaves, but no flowers so far. I was told by Behnkes that they like the shade, but a friend told me they don't bloom if they don't have enough sun -- do you think this is the problem, or is it still "settling in?"
P.S. I heard you on WAMU last year and guess you are a long-transplanted Brit, like me. I am a novice, but enthusiastic gardener, and am amused that people seem to think I have a natural gardening ability just because I am English! I am trying hard to live up to my friends' expectations. Also, after hearing you extol the environmental virtues of using a hand mower, I am no longer so embarrassed to use this "primitive" method for my tiny lawn. I hate the sounds of power mowers and especially leaf blowers (I find raking quite theraputic) To me, gardening is a wonderfully quiet activity.

Adrian Higgins: Climbing hydrangeas actually prefer a little shade, and they will bloom nicely in partial shade. They take a while to get established. I waited six seasons for my first bloom, but the flowers appear exponentially every season afterwards. Reel mowers are good, the problem with them is that they don't allow cutting at the height really required for tall fescues in this region, which is 2.5 to 3 inches.

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Kensington, Md.: I had a 3.5" caliper Kwanzan cherry installed last fall and was disappointed to find that the nursery had cut off all the limbs below 6 feet. Now some little shoots are coming out of the lower trunk. Can I hope that they will grow into real branches, or are they just little nothings? Thank you.

Adrian Higgins: These are suckering branches and should be removed. In time your tree will have a broad canopy and you won't worry about the bare lower trunk.

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Arlington, Va.: Spring has sprung and so have the weeds in my garden beds. For years I've been struggling to control several types of white, fleshy root weeds by digging up what I could, to no avail. The worst looks like a morning glory vine. This year I also have a plethora of a multi-leaved, multi-lobed weed, approx. 6" tall, that already created a solid ground cover in amongst my rudbeckia. Any advice?

Adrian Higgins: Some weeds are more difficult to beat than others, certainly established morning glory vines are murder to eradicate, as are thistles. The only remedy is to keep pulling.

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Boston, Mass.: Dear Professor Higgins: Maybe you can explain to me why the seeds (lettuce, broccoli, tomato, portulaca, nicotiana) I've tried to start are all doing so badly? They were put in little peat pots inside a plastic tray and cover, with a gro-light over them 24/7. I kept them warm and moist. Yet resulting seedlings are extremely spindly (hair-thin in fact); many have bent in the middle. Very discouraging!

Adrian Higgins: The growing light should be just a few inches above the seedlings to avoid stretching. Also, the lamps should not be on 24 hours a day, but 16 at the most.
When the plants develop four leaves, replant them (obviously gingerly) in their own little two inch pots. You will need to harden them off gradually before planting outdoors.

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Arlington, Va.: Cicada questions: Will they hit my lilac? Also, I had a front lawn put in two years ago, literally had the old one stripped out and sodded. Figuring I won't get cicadas out of the front lawn.

Adrian Higgins: CIcadas will do a great deal of good in terms of bringing air and water and nutrients to the soil in the tunnels that they leave. They have saved the expense of core aeration of your lawn this spring.

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Rockville, Md.: About 10 feet away from my house there is a maple tree. I have found it near impossible to dig through the surface roots to plant anything in the bed between the tree and the house. The Man of the house says that nothing is impossible, and that he can dig through the roots to plant something. Would this hurt the tree? Or shall I skip this display of manpower and resort to container gardening (in the shade?!).

Adrian Higgins: Heavy handed root destruction will harm the tree, no question. Revert to containers. Might is not always right.

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Free as a cicada: Your passionate response regarding the cicadas under my weedblock clothe encouraged me to rip the cloth up (largely with eyes closed) in order to give the little guys a shot. I have encouraged them all to get out of my yard and give you a buzz by as a thanks.

Adrian Higgins: If I were the Queen of England I would knight you. Arise, Sir Cada.

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re: Weeds: What is your position on products like Preen?

Adrian Higgins: I am not inherently opposed to herbicides, they certainly are a useful tool under certain circumstances. But treating weeds without addressing the underlying problem won't fix anything in the long run. A weed moves in where you have created a vacuum. If you keep your plants healthy and robust, and weed beds regularly (by hand) and lay a thin blanket of mulch, weeds should be less of a problem.

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Fairfax, Va.: We're new to northern Virginia and are wondering where to find information about native plants and places to buy them.

Adrian Higgins: Go to Green Spring Gardens Park in Alexandria, where they have a native plant demonstration garden. I believe the visitors center there also has information on native plant societies and events, including plant sales.

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Baltimore, Md.: Hello Adrian-

What do you recommend for a 5-7 foot privacy shrub/tree? I'm creating a sitting area and want some privacy from my neighbor, but don't want to create a massive screen.

Also... how do I get rid of onion grass?

Adrian Higgins: Some of the merserve holly varieties, or conside a tall grass such as miscanthus.

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Cicada Friendly: Hi Adrian, I am in Arlington, Va., and looking forward to this long-awaited visit from our guests. I had planned on just cleaning up after them (raking their shells), but I have since heard that their decaying bodies contribute a massive amount of nitrogen to the soil. But I have also heard that a bunch of wet, dead cicadas will smell. To rake, or not to rake, that is the question.

Adrian Higgins: I don't remember them smelling, nor can I imagine they would add much nitrogen. They dry out and litter the place. Maybe we can start a line of jewelry with them.

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Burke, Va.: I live in a three-story townhouse. I am removing a dead dogwood tree in my front small yard and would like to replace it with another tree, preferably one that will give shade and privacy to the front of my house and grow at a good rate. The front of my house gets Eastern exposure.

Can you give me some suggestions as to what tree would be best and when I should plant it.

Adrian Higgins: What you don't want to do is fall into the trap of planting something that will grow so fast as to give instant screening butafter four years will squeeze you and all your plants out of the garden. I would consider an upright Japanese maple, maybe a redbud of some variety, a crape myrtle, or Japanese snowbell. These are all deciduous, of course.

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Arlington, Va.: Mr Higgins, it was thrilling to see you on the Merrifield Gardening show the other Saturday. Thanks for that. I wanted to call in and ask this question but I was too star struck.

I have an elm tree, probably 80 years old or older, and it has a ton of surface roots. I want to put in some raised beds in the area, and I am wondering if I cover two or three of those roots, will it do harm to this valuable tree? It has slime flux already, so I don't want to stress it any further.

Adrian Higgins: I am humbled. If you have an 80 year old American elm, you are to be congratulated since 95 percent of them are now gone. I would devote all my effort with this plant to keeping it free from Dutch elm disease and not really worry too much about the root zone. Certainly you don't want to do anything that would be detrimental to the tree, in terms of root disturbance, excessive watering, application of fertilizers and fungicides to flowers. etc. You might consider planting a little moss between the deepest crevices. I started late due to technical problems, so will be here for another five minutes or so.

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I'm on to you!;: Everytime someone asks about onion grass, you avoid their question!; Could it be, that you too don't know how to get rid of that pest?!;

Adrian Higgins: No. I think I once offered the idea (not mine I concede) that if you bruise the leaves, they will take up a herbicide more effectively. What I try to do is wait until after a good soaking rain and then pull them. This takes skill, because if you tug too hard they will snap and you will leave the bulb. Wear rubber gloves to avoid onion hands. You touch on a good point. I don't know all the answers, I'm just relaying my own experiences.

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Cleveland, Ohio: Am I too late to plant trees and shrubs? How much time do I still have this spring?
Thanks!;

Adrian Higgins: Landscapers plant things all through the year. You can do it, but the risks of losing a $200 sapling are higher if you plant it in June than in September because of the heat stess piled on tranplant stess. If you do the ground work, plant the crown a couple of inches proud of the grade, and then mulch it correcly, with a watering saucer of mulch, you should be all right. You must walk a very fine line though between giving a new plant too much and too little water in its first summer. Water perhaps once a week to a depth of four inches. Don't water every day, this is a common mistake that kills new plants by the gross.

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Bethesda, Md.: Adrian
Thanks for doing these chats. Could you be so kind as to advise me when the optimum time would be to plant Provence lavender?

Adrian Higgins: Now is a good time as they approach bloom. Thanks for bearing with us this week. Same time next week, and keep those cicada reports coming.

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