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.

He was online Tuesday, July 1 to offer advice on lawns, flower beds, vegetable patches and window boxes.

A transcript follows.

Catch up on previous transcripts of The Garden Plot.

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."

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Alexandria, Virginia: Did you by chance live in Montevideo, Uruguay in the early 1950s?

I knew somebody named Adrian Higgins there and wondered if you could be that person.

Adrian Higgins: Yes, but I was using an alias, Nigel Shorts. (I've never been to the Southern Hemisphere in my life, officer).

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Washington, D.C.: Last week a Richmond gardener asked about growing a gardenia. I live in Georgetown - which admittedly seems to have a mini-Zone 8 climate - and I have had a gardenia in my backyard for five-or-so years. It really likes the weather this year and is covered with blossoms. My garden faces South.

Adrian Higgins: This is very useful, thank you. Kleims Hardy and Chuck Noyes are two good choices up here. Although G'Town gardens have an amazing microclimate. I once knew of one that not only faced south but was coddled by walls in a garden where the owners kept the swimming pool covered and heated, so the roses didn't stop growing in the winter. It was a little unsettling, to be honest.

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Rockville, Md.: I am sure you have had this question before, but what is your favorite tree?

Adrian Higgins: When I was a kid, I used to buy a toffee bar and climb a favorite horse chestnut tree and just sit and watch the world below. Horse chestnut trees don't do well in our climate, so that isn't an option any more. I love crab apples that grow craggy with age, and are covered in blossoms in spring and decorative fruit in autumn. The key is to pick a variety that will not develop rust or scab.

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Bethesda: Dear Dr. Higgins,

I hope you can help a real beginning gardener. I planted a butterfly bush (actually it is like a tree) in a sunny spot. It is doing well, with lots of pretty flowers. However, it is growing out of control. Can I snip it back a little, even though it is flowering?? Or should I wait?? Any help would be appreciated. Thanks so much!

Adrian Higgins: I would wait until after flowering and then cut it back quite hard, perhaps removing a third of the branches and foliage, and it will thicken up and bloom again in early fall. The basic regimen for buddleia is to cut it back hard in late winter, perhaps to 24 inches, and then trim the new growth by about a third to a half in May. This will keep it bushy and floriferous.

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Reston, Va,: Last week I collected seeds from a friend's wisteria plant and wondered how easily it would start from seed. Any ideas?

Thanks.

Adrian Higgins: I wouldn't. It will take for ages to flower, years, and won't necessarily have the traits of the parent. I'd buy a vine, though they are considered an invasive pest in open areas, so if you are close to woods I would try something else. There is a native version, which flowers later.

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Silver Spring, Md.: Yesterday evening before the rainfall, I sowed some flax and bachelor button seeds that I'd collected late last summer on an assignment to Oregon (and nearly forgot about) and had stored in little envelopes in the fridge.

I'm uncertain about my timing on sowing these and wonder whether I would have been better off waiting until fall?

I'm hoping they come up like larks ascending.

Adrian Higgins: I'm sure they would come back, given your obvious care.

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Arlington Va.: I have about a dozen heirloom tomato plants. Ten of them are doing very well, but two of them (Black Krim) are tall like the others, but the leaves are turning black and dry from the bottom up. They crumble when you try to remove them. It is only these 2 plants. Do you know what the problem is and how I should remedy the problem?

Adrian Higgins: Doesn't sound good, it might be a wilt disease, unless it's some sort of spray damage. I would remove the blackened leaves immediately and wash your hands before touching other plants. If it progresses, yank out the diseased plants and bag them. I would also mulch with straw.

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Anonymous: Thanks for taking my question. I am trying to finish an ornamental memorial garden here in the city. I have gone through several kinds of hydrangeas and they just don't do very well. So, what do you suggest to replace them in a shady area that would provide long-term eye appeal?

Adrian Higgins: If is it on the dry side, I would try any number of yew varieties, as well as (dull I know) aucuba. I would also consider some perennials such as Mrs Robb's Spurge, hellebores and geraniums.

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First Time Vegetable Gardener: Hi, Adrian -- I'm a first time veggie gardener (well, first time in 30+ years since I was a kid and helped out my mom) with 3 4'x8' plots filled with veggies. For stuff like squash, watermelon and tomatoes, I can tell when it's time to harvest.

However, I also have onions, carrots, sweet potatoes, arugula and bibb lettuce. With the root veggies, how do you know when it's time to harvest?

For the greens, do I just pick off leaves as I need/want them or do they grow heads that are harvested whole?

Thanks for the help!

Adrian Higgins: With head lettuce, you normally take the whole plant, at the size you want, but before it bolts. With leafy lettuce, and other leafy greens, you can snip off the leaves with scissors and they will grow some more. Onions are taken when the foliage begins to wither. Unless you are growing them as spring onions, and can take them once they reach a desired size. Carrots take about two months to reach a harvest size, and then can be basically stored in the ground. I have harvested carrots right through the winter.

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Charlotte: My hydrangea has bloomed spectacularly this year, but now the blooms are fading. Should I take them off?

Adrian Higgins: No, it won't promote reblooming and they look fabulous as they age and dry.

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Martinsburg, W.V.: We have an area at the front of the house - facing east - that needs a plant (or 2). We're looking for something that will flower but won't be more than 3x3. Suggestions?

Adrian Higgins: I would consider some daphnes, perhaps Carol Mackie. Or Corylopsis.

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Richmond, Va.: Is there a better time of year to start composting than others? I'm pricing tumblers now for my smallish yard. Is it OK to start in the summer, or is another season better? Thanks!

Adrian Higgins: Certainly, warm weather will speed the decomposition, so now is a great time. Truthfully, anytime is a great time to start a compost pile.

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Springfield, Va.: Ants have been incredibly infestuous this year in our neighborhood. Is there an effective way to limit their populations? I've tried all kinds of chemicals and treatments with only mild success (once it rains, they come storming back). It's not just my home, which we keep pretty tidy, because my neighbors have been complaining too.

Adrian Higgins: My only suggestion would be to attract songbirds that will eat them. Chickadees, wrens, catbirds, thrushes, all would like to snack on an ant.

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Washington, D.C.: I know this is not really an open topic, but I am partial to live oaks myself.

Adrian Higgins: I definitely prefer them to dead ones. (Sorry). Live oak is supposed to be hardy to our Zone 7, so it might work, and it is a lovely tree. You don't see many around here.

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Alexandria, Va.: I looked on a Virginia website for hardy native shrubs and found the New Jersey Tea. The description of pretty flowers, humming-bird and butterfly attracting, drought-resistant, make your own tea, and ease of growing sounded so good that I wondered why I don't hear of these anywhere else. Am I missing something?

Adrian Higgins: It's a lovely if understated low growing shrub and it should be used more. The botanic name is Ceanothus americanus.

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Brooklyn, N.Y.: My broccoli is flowering. Am I to pinch off the flowers for growth? thank you

Adrian Higgins: No, harvest the terminal buds, this will promote laterals for later harvest.

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Washington, D.C.: Good morning. I know there are some plants that are heavy feeders, geraniums, roses, etc. Feeding other plants encourages foliage at the expense of flowers - clematis, morning glory, etc. Is there any good rule of thumb for helping keep me remember which to feed regularly? What about tropical plants such as cannas?

Adrian Higgins: Generally, lush tropical plants are heavy feeders, but what they really respond to is lots of watering. Generally, stay away from high nitrogen fertilizers, which push growth at the expense of flowering. It is far better to err on the side of underfeeding plants than to overfeed them. The key is a good soil mix (in a pot) or well amended garden beds. A thin layer of compost does wonders.

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Portland, Ore.: Hello Adrian, I know it's still early in the growing season, but once again I seem to be on track to grow a puny, sorry patch of peppers. I know it isn't easy here in the Northwest where night time temps even on the hottest days get down into the low 60s, 50s even sometimes. But my friends seem able to do it. Year in, year out I see other people's pepper plants get big and bushy while mine, typically store bought starts, go into the ground (maybe a bit too early, but no earlier than my friends) and they develop (I see some flowers starting to emerge down in their tippy tops now) but the plants remain tiny. They've hardly gotten any taller since I put them in. I'm growing in a somewhat new bed, put in last year -- a mixture of probably 4/5 garden compost 1/5 manure. No amendments this year. But still I seem headed for the same results I always get. Tiny plants. Tomatoes right next to them are humming right along. What am I doing wrong? Do you have to feed constantly to grow healthy, leafy pepper plants that will ever grow taller than about 15 inches?

Adrian Higgins: I wonder if you need to start pepper plants indoors in March so that you have really large plants ready to go for your somewhat shorter season. You may be choosing the wrong varieties too. The other obvious problem is a lack of sunlight, peppers demand full sun. I would talk to gardeners who are doing well and get their advice.

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Gainesville, Va.: Loved your 6/26 Harvesting Food and Knowledge article. Interested in growing lots of food, especially peaches as well as other fruits. Local well-established and respected garden center told me "no can do" without spraying heavily several times a year. What do the community gardens do to realize their peach yield? And other fruits? Any comments and/or follow up article on growing FRUIT TREES successfully organically would be fabulous...

Thanks.

washingtonpost.com: Harvesting Food And Knowledge (Post Home Section, June 26)

Adrian Higgins: The 7th St. garden had lovely peach trees, bearing so well. The gardener there said they were not sprayed. Peaches are plagued by an insect pest called a plum curculio, which lays an egg in the nascent fruit and ruins it, and by brown rot. The only reason these trees were spared these pests is that there have been no other peaches grown in this vicinity for a long time, and they are young. You can spray organically against brown rot, I'm not sure if there is an organic control on peaches for the curculio. On apples, they spray a kaolin mixture, perhaps it might work on peaches too.

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Wokingham, UK: I'm just starting to gather the harvest from a patch where I planted 18 seed potatoes. When it's bare, would you recommend any other vegetable that would be ready for the new year?

Adrian Higgins: What about carrots or beetroots?

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Gardenia: That hardy variety is Chuck Hayes, not Chuck Noyes. I've got a couple in bloom in my Shepherd Park garden.

Adrian Higgins: Yes, I'm losing the plot.

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Alexandria, Va.: Hello -

Why why why do my Gerbera Daisies die? I've tried everything - but they either die or just never bloom. Is there a trick?

Help - I love them but they don't love me, and I have a green thumb!

Adrian Higgins: It's too hot and humid for them to exist as a perennial in our climate. Pretty things though. Nice to have for a few weeks in the spring, greenhouse grown.

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Harrisburg, Pa.: Help! I'm being invaded by Japanese beetles. My roses look like Swiss cheese. I've declared war, but my Sevin seems to wear off each day. Any other suggestions?

Thanks.

Adrian Higgins: This is alarming because the word on the street is that the Japanese beetle problem this year was going to be much diminished because of last year's drought. Perhaps you got more rain than we did in D.C. You can pick them off and put them in a jar of bleach solution. The key is to get the early scouts, because once a few start munching, they signal to all their pals to join the feast.

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Arlington, Va: Good morning! Is it just my yard or are we having a serious lack of butterflies this year? My butterfly garden (butterfly bush, coneflower, etc) is virtually unvisited except by finches and my neighbor's abelia which is normally covered with swallowtails is also lonely! I do get plenty of bees which is good but, it's still worrisome. Are others experiencing the same?

Adrian Higgins: I think it is still early in the season, though I too have thought that we might have seen more swallowtails and fritillaries by now. The key to luring butterflies is growing nectar plants for the adults, but foliage hosts for the larvae. Also, butterflies actually go dormant when temperatures top 90 degrees.

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Falls Church, Va.: I have this ugly viney weed thing that is cropping up on several of my azeleas. It has a very think stalk and these horribly ugly leaves and it wraps itself super tightly around the branches. The whole thing completely grosses me out. Is there any way to stop it?

Adrian Higgins: Yes, put on some gloves and pull it out. If it is poison ivy, however, be on guard.

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Hydrangeas: My husband and I moved to a new home a few months ago. This past month we were excited to see a hydrangea plant start to bloom. However, we only had two flowers bloom and nothing else! Is there anything we can do to make sure the whole plant blooms either this year or next? Thanks!

Adrian Higgins: One of the main reasons you lose blooms is people think it needs pruning back hard at the end of winter, and they remove the buds that will produce flowering canes.

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Arlington, Va.: The Emerald Green Arborvitae is the exact type of tree that I need for a live privacy "fence" when it reaches maturity. However, I fear that these trees might split apart due to the lack of a single trunk. Is this a problem? If so, what do you recommend? Thank you.

Adrian Higgins: No, this conifer doesn't have that reputation. It might break in a wet snow, but other than that you'll be alright.

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NYC: Last week you mentioned companion planting. I see there are several books about this. Are there any particularly good ones you could recommend?

Also, thank you so much for doing these discussions. Every week I learn something new and useful from you. My garden thanks you too.

Adrian Higgins: To be honest, I think it's a bit hokum. I put plants together to look good and to perhaps mimic effects in nature.

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Havre de Grace, Md.: Harvested my garlic this past weekend (it seems early, but the leaves said to do it and it looks good). What should I fill the space with now? Is it too late to plant summer seed? (I know it's too early for winter crops).

Oh, and my peppers still seem stunted. They maybe added 1/2 inch and two leaves since we last spoke. My garden is full sun all day (except my okra, which ends up shaded by 5 pm, poor planning on my part)

Adrian Higgins: Again, carrots are a great crop to start now. Or scarlet runner beans, which will enjoy the cooling weather of early fall. Obviously, we have folks with stunted peppers. I'm inviting all you marvellous pepper meisters to share your tips with us.

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Basement Dweller: Hi!

I live in a basement apartment, but as you walk down from the yard towards my front door, I have a wide patio area. I'd love some type of hanging plant (since hanging will maximize the sun exposure). What are the chances I could get an herb to grow in non-direct sunlight? Cilantro, perhaps?

If not, do you have another recomendation? I'd love either function or flowers!

thanks!

Adrian Higgins: It's too hot for cilantro at the moment. I once grew different thymes in baskets, and they worked well.

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Help! My Roses are Infested!: Really hoping you can help me out...For the past two years I having been waging a losing battle with Japanese beetles -- beetles vs. my rose bush. I use Pyola, but the beetles are devastating my roses, and now this year, to add insult to injury, my bush seems to be infested with black spot. I really love roses, and this is my first real garden, but I am so disheartened by the beetles and the black spot that I just want to weep. My parents just gave me a new beautiful rose bush for my anniversary, but I almost do not have the heart to plant it...Is there anything I can do to get rid of the black spot? Any "natural" (or not so natural), DEADLY remedies in my war against the beetles?? Any help you can provide is really, really appreciated. Many, MANY thanks! Simone

Adrian Higgins: As for the black spot. Remove diligent all the affected leaves. This includes the ones that have dropped to the ground. Bag them. Then spray a fungicide to prevent it from returning. Organic sprays are available. Given this wet year, you will need to spray every two weeks until the weather dries up a bit. My earlier advice for the beetles applies. Don't despair, the roses will come back. I would get some kelp meal, alfalfa meal, Epsom salts and greensand and mix them, then top dress a couple of cups of the blended nutrients around the root zone, and water in.

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Watering for transplanted tree?: I posted a couple of weeks ago about a ten-foot holly that was moved from a friend's yard to ours. It was planted immediately and had an enormous root-ball, but I'd like some feeling for how much watering I should do and how often. Let the hose run around the trunk for ten minutes once a week? Half an hour every two weeks? Sprinkle every day? We'd really like to keep this beautiful tree alive through the miserable summer months.

Adrian Higgins: Don't water every day. Form a dish so that water channels into the rootball and give a good soaking (from a five gallon bucket, forget about the hose) once a week. Make sure no roots are exposed to the air.

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Washington, D.C.: Hello Mr Higgins --

My broadbeans have grown impressively but have produced few pods. There are some black markings on them too. People tell me to keep at it. Should I? Thank you.

Adrian Higgins: Beans can develop a bacterial disease that is transmitted by spores carried in raindrops. Try not to handle bean plants when they are wet, you will spread the disease. They are better watered at the roots, not from above.

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What to do with borage?: I planted borage for the pretty blue flowers but I'd like to know what to do with the leaves. Do you put them in a salad, cook them, or what?

Adrian Higgins: You can put the leaves in cold drinks, though I read you can get dermitis from too much contact. They are in bloom now, and lovely garden plants. The bumble bees love it. We're out of time, but would love to get some input on pepper plants that I can post next week. See you in Thursday's Home section.

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