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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Fairfax, Va.: Hi Adrian --

I love these online chats! Can you please tell me (in your estimation) what are the five most prevelant summer weeds and the five most prevelant winter weeds which appear in our lawns in this area?
Thanks

Adrian Higgins: In the winter, you have crabgrass seeds ready to germinate in April and the dandelion, which is a perennial broadleaf weed. If your lawn is thin you will have such winter weeds as henbit and chickweed.
Summer weeds, wire grass, wood sorrel, crabgrass, and clover, if you count the latter a weed.
The cardinal rule of lawns and weeds: The thicker the grass, the fewer the weeds. Get overseeding.

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Springfield, Va.: Hi Adrian, I hope you can help settle a debate. I have some holly bushes that are over 20 years old and have become quite large and when I prune them they are pretty ugly and woody. I want to pull them out and put in something new. My neighbor says I can prune them to the stump and they will come back. What would you do?

Adrian Higgins: I have removed old, spindly American hollies to the ground. They do resprout, but not in a way that attractively rejuvenates the plant, in my experience. Better to dig them out and start again. If you were talking a yew or cotinus or lilac, I would say go ahead, but not with a holly.

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Germantown, Md.: There is an article about growing passion flowers in today's paper and it says Caerulea is hardy in this area -- is this true, even up in Germantown? I have a caerulea that is rapidly outgrowing its pot (started from seed this spring -- it's an amazingly fast grower!) and I would love to grow it up a trellis against my two-story deck. This is a relatively sheltered spot as there is a tall hedge of cypress right next to the deck and has a western exposure. When should I plant it out? Can I do it this fall or should I wait till spring to give the plant more of a chance to establish before winter cold?
Thanks!

washingtonpost.com: Passionflower: Fall's Showstopper, (Post, Sept. 9)

Adrian Higgins: Plant it now in good soil that drains well and it will develop a nice root system before the freezes arrive with the holidays. Make sure it is watered occasionally, especially if the fall is dry.

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Clinton, Md.: At the beginning of summer I planted a beautiful canna, but by summer's end the canna was destroyed -- eaten by some type of insect. I noticed a two ladybugs on it, but thought they were good for flowers and the garden. Could they have dined on the canna?

Adrian Higgins: No, most ladybird beetles eat other insects, not plants. I wonder if you had slug damage?

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Rhode Island: We just bought a home and removed an in-ground pool from the back yard. We now find ourselves with a pit of sand 15 feet across and 8 inches deep with about 6 inches of sand. Any thoughts on what we need to do to grow grass there? Remove sand and add soil? Add soil on top of the sand? Throw in the towel (trowel?) and build a patio?

Adrian Higgins: A number of ideas come to mind, though at 8 inches deep it is rather shallow. You could convert it to a decoratIve pond, though at your latitude you would need to drain it in the winter and find a home for aquatic plants. You could convert it into a bog garden with interesting plants such as pitcherplants and sundews. You could build it up and use it as a rock garden, knowing that it would provide the subsoil drainage you would need. You could fill it in and grow grass there, though the drainage and nutrient differences with the rest of the lawn may mean that the stand of grass will never look the same as the rest of the turf.

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Washington, D.C.: Dear Mr. Higgins: I am planning an indoor/outdoor event for the first week in May 2005. My small city garden currently contains summer bloomers -- daylilies, coneflowers, black-eyed susans, etc.; howeverer, it is rather blah looking in late spring. What can I plant now to give a good diplay next May? Recently, I looked at allium bulbs at the nursery. Would they be a good choice? Your suggestions would be very much appreciated. Thanks

Adrian Higgins: I wouldn't rely on bulbs alone, but alliums are a good choice because many varieties do bloom in May. I would plant low growing satsuki azaleas with scilla and camassias and bearded irises, with lots of filler foliage from say hostas and ferns.

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Alexandria, Va.: I need some ideas for fall planting in fron of my off-white brick townhouse. I am not into color unless it is subdued. Any interesting foliage ideas? Thanks for your help!

Adrian Higgins: Any shrub that can be trained to create a tracery of dark stems against the white would provide ornament year round. The key would be in shaping them and achieving the bare lower stems when they are young. Consider amelanchier, upright Japanese maples, even a lovely bamboo called Phyllostachys nigra whose older stems turn black. You will need to put some sort of barrier around the planting to prevent it from spreading.

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Falls Church, Va.: Adrian, my back and side yards are rather severely sloped. I'd like to terrace them, easily and cheaply. Any suggestions on terracing materials and what to plant? Thanks!

Adrian Higgins: Terracing can be tremendously expensive, especially on steeper grades. Cut and fill to create paths traversing the hillside and retain them with cedar boards that are pegged with wooden stakes. That is a relatively low cost (but high labor) solution.

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The land bindweed has not forgot: I (hope) I'm well on my way to defeating the bindweed invasion of my flower garden. Am I doing a bad thing by putting all the vines I pull up into the yard waste recycling? I think it gets turned into mulch.

Also, can you identify a perennial that had dark green leaves with maroon veins that look like marijuana leaves, woody stems, and large red flowers that look like hibiscus but flatter? Thanks!

Adrian Higgins: As long as the bindweed debris doesn't include flowers and seed, I think it should be all right. I don't know what the perennial is, except there are some varieties of hibiscus with the types of leaves you're describing.

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Bethesda, Md.: Good afternoon! I gathered a nice bunch of Tiger Lily seeds this year, planning to plant them in a similar, if dryer, climate than Washington's. But when I started looking up info for planting tips, I read in your book that what's commonly referred to as Tiger Lilies are actually another variety.

These are the orange kind that grow like mad on the border of the roads and almost everywhere else. Any suggestions? Thanks!

Adrian Higgins: Tiger lilies have black bulbils in the leaf axils, from which new tiger lilies will grow if you plant them.

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Washington, D.C.: Someone recently asked about where to get garlic seeds. I saw them last Sunday at the Dupont Circle Farm Market (Sundays 9 a.m. - 1 p.m.). Also you can order them from www.growitalian.com.

Question: I had very good yield from my green beens this year, but towards the end they were attacked by yellow beetle like bugs. I'm in an organic community garden so I can't use poisonous sprays, but I'm concerned about eggs from these bugs being in the soil and attacking my plants next year. I can plant the beans away from that area, but I'm afraid those ugly yellow bugs will hunt them down. Any suggestions?

Adrian Higgins: Useful information. My advice is to order your garlic seed now because when it comes time to do so in October, most of the varieties you want will be gone. YOur beans may have been attacked by the bean beetle. The standard advice is to clean up all the debris after harvest, turn the soil this winter to expose any eggs to frost, and plant your beans somewhere else next year.

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Bethesda, Md.: Sweet tomatoes have finally arrived to my garden, but squirrels have noticed them, too, and we're fighting what seems a losing battle. The plants are too large to cover with a net. Will sprinkling cayenne pepper around them work? I did this when I attached a bird feeder to the window, it didn't bother the birds but squirrels seemed to stop gathering under the feeder or trying to jump to it. Any other suggestions to keep them at bay? Thanks.

Adrian Higgins: Possibly, though I imagine a wayward piece of pepper could alter the tomato tasting experience entirely.

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Alexandria, Va.: I have several Hostas that are doing very well in a section of my property but want to move them to the side of the house. Wondering if this is a good time to transplant them. Some of them still have flowers.

Adrian Higgins: Wait until the flowers finish and then lift and divide them. September is the optimum time to lift and divide perennials because you don't have to worry about disfiguring the leaves, they have done their work for the year. I am interested in learning what others do with their spare divisions, do you find takers for them and can you count on them planting them with dispatch and care?

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Washington, D.C.: I live in an apartment, and like to help friends with yard work. I also just took Montgomery County Parks' Weed Warriors course, so I am now up on the invasives. One friend I'd like to help told me that her backyard is "basically all weeds..." If that's so (I haven't looked yet), and by pulling the invasives I'll be leaving big gaps, I suppose I should be prepared to help her choose and install shrubs and perennials, etc. I've never planted shrubs, however -- what's the best time of year to do that, and how do I find out about the mechanics of this kind of planting?

Adrian Higgins: Filling gaps in garden beds is important, because if you don't weed will move back in quickly.
But it is also important that you don't stick in a plant that will way outgrow its allotted space. Most perennials have a finite spread, but woody plants can sprawl for many feet, so it is vital to know the mature size of whatever you put in. As for planting, now is a terrific time to plant both perennials and, especially, trees and shrubs. The most common pitfalls for beginnings is in digging too small a hole for the new plants, failing to score and tease out roots, planting too deeply, and smothering new plants with mulch. New woody plants need a good soaking when planted and another in a month or so, especially in a dry fall. They need similar soakings their first summer and during periods of drought. But do not overwater, or you will kill the plant.

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Delray, Va.: Is there a kind of hosta that you can plant in fall and that will last all winter? A friend of mine wants to plant some this fall, but I thought they only come out in spring and die off in the fall.

Adrian Higgins: The latest hosta I know is called Hosta tardiflora, and it blooms into November. But eventually the leaves will die back. Hostas are meant to do this. Being deciduous is a way for plants to live in areas with cold winters.

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Frederick, Md.: Summer's almost over and my flowering plants are fading away. frown. I want some fall color in my garden but I do not like mums or kale. Anything else out there that is pretty carefree to grow in the fall?

Adrian Higgins: There are many types of chrysanthmums, including more daisy like in habit, such varieties as Sheffield Pink. Other fall blooming flowers include goldenrod, tender sages, inulas, helianthemums, sunflowers and lots of different asters. The difficulty is that short of buying large container plantings now and sticking them in, the more economic and horticulturally sound approach is to plant and sow these things in early summer or late spring. Also, perennials that you buy now will be young and spindly. I would splurge on some flowering plants in pots, dig them into your border, but plan this winter to go to town next year. Also, fall ornament is derived from leaves, grasses, and the whole kaleidescope of late season beauty, not just blooms. Though these are important and serve to perk up any border.

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Arlington, Va.: Is now the right time to spray poison ivy vines and roots, or should I wait a bit longer? I'm OK with using Roundup -- is this the most effective spray? Many thanks.

Adrian Higgins: The late season is the best time because that is the period the plant is storing sugars and will translocate the herbicide to the roots, where it will kill the weed.
Roundup or others containing glyphosate seem effective and are universally used. They are considered of lower impact on the environment than harsher herbicides because the chemical breaks down quickly with no lasting presence.

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Gambrills, Md.: I am growing a peach tree from scratch in a container on my deck. The three seeds have sprouted to a height of about two feet each. I am wondering what I should do when the temperatures eventually start going south? Do I leave the container outside? Should I plant the saplings before the first frost?

Adrian Higgins: Peaches are hardy plants and need cold dormancy. Saplings, though, are most at risk in their first winter, so you should give them a temporary winter mulch after a good watering. The mulch is removed in March. I would wrap the bark to prevent rodent damage and sunscald and plant htem in a location that will be protected from northerly winds. However, I would advise against giving them too much of a microclimate, such as against a south facing wall, because this will draw them out of dormancy early and cause forst damage.
The seedlings will not produce the same fruit as the parents, and may be inferior in a number of respects. But the accomplishment of growing them from fruit is not to be dismissed. Well done.

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Washington, D.C. (U-Street Neighborhood): I wrote in last week about my Croton. It is still not doing well. The colors are no longer vibrant. The leaves are droopy and sad looking. It has thise white formations on the stems and leaves. It's become an eyesore... I'm thinking about calling Dr. Kavorkian to put it out of its misery.

Can you recommend another plant that is not so needy and susceptible to trauma?

Adrian Higgins: Since last week, I looked up the website of Glasshouse Works, which has a section, I believe, on Croton culture. (This sounds like a script from a bad Star Trek episode). You might want to check it out. Certainly there are easier houseplants to try.

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Sterling, Va.: We have a smallish Magnolia in our front yard (that gets pink blossoms. I think it is called a Star Magnolia). It's only about 8 feet tall. At the beginning of the summer we noticed that it had all kinds of bees and flies swarming all around it. Upon closer inspection we noticed a black tar substance on many leaves. Some Internet research revealed that our Magnolia has a bad case of scale. And indeed the branches are filled with bumps. We purchased horticultural oil from a garden center and sprayed it last weekend (with water dilution). So far nothing seems to have happened. What procedure can we use with this oil (it says not to apply any more than once a month)and what results can we expect? Is there any saving our poor little tree? Thanks.

Adrian Higgins: Yes there is saving the tree and you have taken the right steps. It would have been better to have sprayed when you first noticed the symptoms, but at least now you will have interrupted the cycle of the scale insect. The oil works by smothering the insect but the results take time and you will not of course reverse this season's damage to the leaves. In addition to spraying the stems, spray the upper and lower surfaces of the leaves. Spray again before the leaf drop and apply a winter spray (more concentrated solution) in February and keep an eye on it.

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Silver Spring, Md.: Adrian,
I started preparing to plant some shrubs in front of my house which I purchased less than one year ago and discovered concrete in some places. The front is completly bare and the area I was planning on planting is the sides of the small porch against the house. (The most logical and natural place)It seems my 62-year-old house was completely renovated five years ago and this is the old drive way. I am looking for hardy shrubs, colorful ground cover or perennials with good color that have shallow roots. The area gets lots of sun particularly the early morning sun.
Thanks for any suggestions

Adrian Higgins: Planting over buried concrete is fraught with potential problems, including lack of roots run and flooding. If you cannot remove the concrete and need to plant above it I would go with some shallow rooted ground cover such as liriope or even dwarf azaleas. Unfortunately we have run out of time. See you next week after another crazy weekend of garden work.

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