Summer Gardening
Adrian Higgins
Washington Post Garden Editor
Tuesday, June 24, 2008
11:00 AM
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, June 24 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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Pittsburgh, Pa.: I just wanted to pass along an experience of mine regarding destructive insects. I have a small garden where I like to grow some potatoes. Recently, I noted an infestation of the Colorado Potato beetles. I handpicked what I could find and removed any egg masses that I could see. Over a period of days I noted an increase in Daddy Long Legs spiders, Lady Bugs and other insects. With my efforts and the beneficials helping out at this point the Colorado beetle are gone. I also cut all my asparagus plants to the ground recently and haven't seen a single asparagus beetle since. The asparagus is now left to go to fern. I was tempted to spray but, I was truly amazed at how the beetles were eradicated. Now if I could find a way to eliminate the cucumber beetles!
Adrian Higgins: Great story, thanks. One tactic against the cucumber beetle is to sow your seeds now, i.e. late, for a mid to late season crop when the beetles are not so abundant.
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Rockville, Maryland: OK. I have my three tomato plants in the pot on the balcony and they are happy enough (when I remember to water them) and they are very green. But no flowers or fruit.
What should I do?
Appreciate the green?
Adrian Higgins: Be patient, it has been a cool cloudy spring and plants are behind a couple of weeks or more. Also, you must ensure that the plants are adequately (but not excessively) watered to minimize the development of blossom end rot on the fruit.
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Central Virginia: In last week's chat, a reader asked about getting rid of woodchucks. Well, since this is anonymous, I'm willing to share my tactics.
A woodchuck dug a hole beside my foundations and would NOT leave. I tried everything! I'd fill in the hole with sharp gravel, I'd shove mothballs down the hole, I'd stick a hose down there and try to fill the den with water, and that blasted oversized rodent would just redig the hole, kick the mothballs out, and put on his galoshes.
But I fixed him. That sucker's gone! I'd heard that woodchucks hate the smell of used cat litter, so I put some of that down the hole, and then I thought, "What if it's the smell of cat urine they don't like?" And then I thought, "Cat urine, eh? I can go one better than that!"
So, morning and evening, for two or three days, I'd pour a mayonnaise jar of urine down the hole. (I'd cap it and let it sit for several hours first, to intensify the odor.) After the first day, he moved out, and he hasn't been back since. And if he does show back up, I can get another mayonnaise jar!
Adrian Higgins: Personally, I prefer to unleash a family of skunks on those groundhogs. That really does the trick.
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Arlington, Va.: First year growing cilantro from seed and I'm amazed at how fast it bolted (supposed to be a slow-bolt variety too!). The plants were still so small, so I really hadn't pinched them at all - there wasn't enough to make it worth harvesting yet. Was that my mistake? I have sowed some more seeds and am hoping for better results with round 2. Thanks.
On the plus side, the basil is loving this weather.
Adrian Higgins: Cilantro likes it cool, as you have discovered. I would save your seed until August and sow then for a fall crop, and sow every week or two to keep it fresh.
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Strasburg, Va.: This wet and hot spring and early summer has left one group of my peonies covered with white powdery mildew.
They are strong vigorous plants (Sword Dance) - should I cut them back to the ground and dispose of the infected material - or just spray with baking soda and keep the leaves/stems?
If it was anything but a peony I would have cut them back already. Thanks
Adrian Higgins: It's early to cut the foliage. I would spray with baking soda and hope it doesn't get worse. Ironically, powdery mildew seems to be worse in dry years. Perhaps you should move your plant to an area with better air circulation.
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Infested Office, D.C.: Dear Mr. Higgins,
My beloved begonia (happily living on my windowsill at work) is harboring little black flying bugs. They're not doing anything to the plant, but I fear a massive infestation of my office and the wrath of my co-workers.
Do you have any advice on how to kill off the bugs? I can spray something on Friday evening and leave the door closed over the weekend, if that helps...
Thanks so much!
Adrian Higgins: This sounds like fungus gnats, which thrive off soil that is constantly moist. You could spray them with insecticidal soap or use a yellow sticky trap. Then put a thin mulch of gravel or grit in the pot, and cut back on the watering a bit. That should do the trick.
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Chesapeake, Va.: I have a brown thumb. I love plants, and I try really hard to take good care of them, but they never last long. For instance, I bought some blueberry bushes and planted them next to my house where they would get plenty of sunshine. I watered them every day, and they still withered and died. My daisies never last long either. How can I tell what soil is the right soil, what water is the right amount?
Adrian Higgins: They withered and died because you watered every day. Nothing should be watered every day, except plants on balconies in pots, or bonsai. By amending soil and then giving your plants a thin mulch, you enable the rootzone to remain amply moist with occasional deep waterings. You should only water when you feel the top inch or so is dry.
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D.C.: What would you do if someone knocked on your door and offered to spray the entire premises for insects for $75? It happens often.
Adrian Higgins: This is awful. What insects? What are they spraying with? Are they licensed and trained? This is like someone arriving to say I want to spray nerve gas in your home. I should alert the authorities.
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Silver Spring, Md.: My neighbor asked me to grow some tomatillos for him - he has no sun in his yard. I checked online and I am concerned that they will turn into an invasive presence in my veggie garden. The variety is Goldie which I learned is more of a ground cherry. Can you tell me anything about this plant?
Adrian Higgins: These are annuals, I haven't heard of them seeding madly like some cherry tomatoes. Go on, be neighborly.
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Richmond, Va.: Is Richmond too far north to plant gardenias? I have a location on the southwest corner of my property that gets lots of sun, that I thought a gardenia would look good in. Do you have any particular cultivars you could recommend? Thank you.
Adrian Higgins: Gardenia should be OK in Richmond, especially if you pamper it for the first two years. I would site it in an east facing bed and spray anti desiccant the first couple of winters.
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Chevy Chase, Md.: Help! My Aucuba Japonica bushes have a lot of leaves that are turning black starting early this spring and are falling off. Is it a fungus? If so, what kind of fungicide should be used? How is it best applied? (leaves? base? how long and often?) Also, a wide swath of pachysandra also croaked last summer (don't think it's related) What would be a hardy, shade-loving and quick growing replacement groundcover? Thanks!!
Adrian Higgins: Both are blights related to the wet spring. You can cut the infected stems, clean up the area, and new shoots should regrow.
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NoVa.: We live in a wooded neighborhood west of town. Lots of trees and weeds in the woods and this leads to invasion of weeds, saplings from seeds, etc., in our yard. We have long, thorny, leafy vines springing up everywhere in the "natural" parts of our yard. I try to cut them back but they keeps re-emerging.
Any idea what this is and how to kill it?
Also, with the bad storms, my flowering perennials are taking a beating (from the hail, etc.) Any ideas to help perk them back upright?
Adrian Higgins: The weed is probably tearthumb, get a thick pair of leather gloves and pull it out. Watch out for poison ivy.
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Washington D.C.: Hi Adrian -- I'm confused about when to cut back my potted hydrangea. It's grown quite big and I'm afraid if I don't cut it back it will be a monster next year. I hate to prune while it's in full bloom, but I know if you wait too long you lose the flower buds for next year. What should I do?
Adrian Higgins: You can take out many of the old canes after flowering, and trim back some of the remaining ones, but not too much. If the shrub is too large for its space, consider moving it in September.
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Gaithersburg, Md.: As an experiment, this year I planted a pumpkin vine in my small garden. Little did I know that it would take over; every day it's crept a little bit closer to the tomatoes, and I expect it will devour them some night while I'm asleep. Can I trim it at all without hurting it? And should I be pinching off flowers, or just let them grow? It has quite a few, but I can't imagine that they'll all develop into pumpkins.
Adrian Higgins: Most of the flowers will be male at this point, you may get four female fruiting flowers on the vine, but I wouldn't cut it back until you can see fruit developing. By leaving just, say, two pumpkins on the vine, they will grow larger than if you had more. Steer the vine tips to their desired course before they root.
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Washington, D.C.: Help, professor. More than half of a 40-year-old English boxwood has turned straw-colored with those branches dry and brittle. Do I prune the dead wood and hope the plant fills in, maybe 40 years from now? Do I replace the bush? Or do I look to another variety of plant that won't succumb to the same ailment and can thrive in shade?
Adrian Higgins: I wonder if they have succumbed to the wetness of the season, if so, the roots have gone and you should remove them. Boxwood enjoy a light mulch and some occasional moisture, but they detest wet soil and should always be planted with their crown a couple of inches above the gradient.
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Brooklyn, N.Y.: Do some plants or vegetables ward off bugs that attack other plants? Are there certain herbs or plants that should be grown near each other in order to protect each other from bugs? I.E. will my rosemary defend my basil or vice versa? And if so, is there a reference guide to this or Web site? Thank you.
Adrian Higgins: This is an approach called companion planting, and yes, much has been written about it. The most obvious use is of marigolds, which deter soil nematodes. Generally, the more diverse your garden, the healthier it will be. I don't think your rosemary will defend your basil (which may get a few whitefly, but that's about all) but it will give you some aromatherapy.
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Springfield, Va.: We had a bartlett pear tree on our front lawn that's been ripped apart by all these winds we've had. Do you have a stronger/prettier replacement?
Adrian Higgins: Two great pears for the mid-Atlantic, Magnus and Potomac. See if you can find them.
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Leesburg, Va.: Hi Adrian, I planted a Red Bud and Yoshino cherry tree in mid May. Both trees had their leaves shrivel up, turned brown, and some fell. My question - is this trauma of planting or are the trees dead? If they are possibly dead, how can I determine that conclusively? Lastly, is there a way of avoiding this in the future when I plant other trees? For the record, I have planted other trees successfully in my yard. Thanks for your advice.
Adrian Higgins: Trees are always stressed when planted. You can minimize the stress by doing this on a cloudy day, making sure the roots are gently teased from the container or rootball, that the tree is planted at the correct height and that the backfilled soil has no air pockets. I'm not suggesting this happened in your case, but the biggest killer of new trees is the owner, who overwaters them, by the way.
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Havre de Grace, Md.: I finally gave up on my pepper seedlings this past weekend. They never got past the 4 to 6 leaf stage, but never really died either. I've replanted with purchased plants in hopes of getting something, but I want to learn what I might have done wrong. I thought it was the cool, wet spring, but even once it finally warmed up, they never grew.
Adrian Higgins: It's still early, I think you should have stayed the course. Pepper plants need full sun, and well drained soil.
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Wilmington, N.C.: Do you have any advice on when and how to divide Yuccas and New Zealand Flax? I have 2 of each that I planted 4 years ago. They have gotten quite large (at least 4 feet in diameter)and put off new plants. I tried to divide with a pitch fork in the spring but the roots were so dense that I wasn't able to divide them.
Adrian Higgins: I would try a pruning saw.
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NYC: Do you know anything about the Mosquito Cognito? It's supposed to get rid of the pests without sprays or chemicals by blocking its senses. Does this work? What is the best thing to get rid of them. They can make it so I don't want to go out back.
Adrian Higgins: I think it's a device that emits carbon dioxide and warmth, and makes the mosquitoes think it's a Homo sapiens. They are then sucked into the funnel. I have a friend with one who reported that it did trap mosquitoes, but not enough of them.
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Frederick, Md: Our irises were wonderful this year and the hostas look great. Both are doing so well, we will need to divide and give away plants - wait until cool fall weather?
Adrian Higgins: Irises are generally divided in late August, and hostas about a month later.
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Kensington, Md.: Good morning,
My lilac has been loving the rain, but I've noticed in recent weeks that select branches appear to be afflicted. The leaves are curling (down) and yellowing. This seems to be random, all around the bush. Should I be treating it with anything?
thank you!
Adrian Higgins: Only if you know what's causing it. Look for signs of bark stripping below the dead areas, which would be the work of a hornet. Lilacs also get borers, so look for holes. You may find a systemic pesticide for the borers but there's nothing you can do about the hornet damage, other than remove it.
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Washington D.C.: Hi there,
My front postage-stamp is planted with vinca, but it has been invaded by crabgrass and weeds of every description. The vinca is thriving, so much that it's hard to find the base of the weeds I want to pull.
Any brilliant solutions for fixing this mess? Thanks so much!
Adrian Higgins: I would get a cushioned kneeler, some sturdy gloves and a weeding tool, and spend an hour this weekend methodically removing the weeds. You can part the vinca stems to see the base of the weeds, and be rough with it if necessary, it will grow back.
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Shepherd Park: Adrian,
I'd like to mention to Richmond that we have a couple of gardenias in our yard that are currently in bloom. The variety is "Chuck Hayes" and they survived the severe roller-coaster winter that we had 2 years ago.
Adrian Higgins: Yes, and I think the other one is Kleim's Hardy. I meant to mention that. Also I hope everyone realizes that my skunk tactic was a joke.
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Pepper Problems: I purchased a pepper plant at the local nursery. The tag claims them to be long, red, slender chilis.
What I have now fruiting look more like bell peppers, stout and boxish.
If they sold me a mislabeled pepper, what to do?
I want spicy not sweet!
Adrian Higgins: Give them to me! I love sweet peppers, I hate hot ones.
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Washington, D.C.: I planted snow peas this spring in a small, full sun bed (grew them up a trellis) along with some thyme, sage, and parsley. I think they're done for the spring (leaves starting to yellow, production slowing down) so I was going to pull the plants and replant in the fall when it's going to be cool again. Any suggestions for something I could plant in that space in the interim?
Adrian Higgins: I might try another vining legume, perhaps pole beans or scarlet runner beans.
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Alexandria, Va.: We have a section of our yard that becomes saturated periodically from a spring that becomes active when we have rains like we have lately. Any suggestions for flowers or shrubs that would look nice and tolerate the wet regime, in a shady fairly wooded area? There are currently some tiger lilies in one of these areas that seem to love it, but I'd like to change things up a little. For shrubs I was thinking blueberries might like this environment...
Adrian Higgins: No, blueberries like it evenly moist but they will perish in waterlogged conditions. I would consider some shrub willows, or red twig dogwood, perhaps some creeping jenny and ferns.
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Brooklyn, N.Y.: May is clearly the best month to visit a botanical garden, at least in my area. Sadly so much is gone by now. Aside from the roses, what's due to bloom soon?
Adrian Higgins: I once looked at a study of flowering perennials at Longwood Gardens, and saw that more varieties bloomed after July 1 than before. It's just a question of picking the right plant. What's going to bloom soon? Perovskia, coneflowers, rudbeckia, hydrangeas, lilies, coreopsis, the list goes on and on.
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bunny central: Hello, I'm the lilac lady from Kensington, forgot part two of my query.
My growing garden has apparently caught the nose of a bunny or three, who are delighting in my daisies and other tender, small blossoms. A fence aside, is there anything that will deter these cheeky cottontails, who aren't bothered in the least by my presence?
Adrian Higgins: I've got foxes in my garden as well as dog who is eager (but easily confused) and still have bunnies. I don't have the heart to trap them, even though they have done a number on my poppy bed. A fence is the only option, I'd say.
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Silver Spring: Is it too late? Should I let the weeds win?
Our postage stamp back yard is over-run by 5' tall weeds. If I hit it with a roto-tiller then mulch over it will I be able to prevent the growth next year? We live in a town house with a shady back yard.
Adrian Higgins: It's not too late to battle weeds. The key is to break their life cycle of germination, growth and reproduction.
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Havre de Grace, Md. (again): So the tiny peppers might still make it? Some of the little 4-leafed peppers remain amoungst the newly purchached ones, as my husband insisted we let them keep trying. He is far more patient than I. We have a large garden (20x40), so there was enough room. I'll let you know if they ever turn into anything.
Adrian Higgins: Stick with them and tell us how they do later this summer.
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New York: You mentioned earlier not to water blueberries too often. However, I keep mine in large pots. Does this mean they need more watering than if they were in the ground?
Adrian Higgins: Absolutely. But make sure the pots drain freely.
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Washington, D.C.: Speaking of withering and dying, one of the shrubs in my new garden died has succumbed to all the rain - since we need to replace it anyway... what do you think of Beauty Berry? Any particular variety you like?
Adrian Higgins: Beauty berry is a splendid shrub. It is not highly ornamental, however, until it sets its purple berries in the fall, so I would not put it in a highly visible spot.I don't like the white fruited form, seems to defeat the purpose. There is a native species, but I have not grown it.
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Richmond Va.: I recently saw an ad for David Austin Roses and looked at the company website and fell in LOVE with a yellow climbing rose, Malvern Hills. I have ZERO experience with rose gardening and am not a terribly patient gardener. Should I give it a try, or realize I'm out of my depth?
Adrian Higgins: Some of the David Austin roses are superb. Heritage is a wonderful performer. However, Richmond is blackspot capital of the world. My first consideration would be resistance to this disease and I wouldn't entirely believe everything the grower/nursery says about this trait.
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Pulaski, Virginia: Good morning,
Last spring I planted two Endless Summer hydrangeas. They did fine all summer but I haven't seen the first sign of growth yet this year. Shouldn't they be leafing out by now? I kept them watered during last year's drought.
Adrian Higgins: I think their Endless Summer has ended. And so, alas, has our session today. Check out Thursday's Home section, and our next episode of Community Plotlines online at washingtonpost.com
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