The Garden Plot

Adrian Higgins
Washington Post Garden Editor
Tuesday, July 11, 2006 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.

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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Youngstown, Ohio: Hi Adrian; love the weekly chats. I just discovered an infestation of japanese beetles on my two weeping cherry trees; planted this spring. What's the best way to get rid of these suckers w/o harming my German Shepard Spencer? Thanks.

Adrian Higgins: The dreaded Japanese beetle. There is no easy solution. If you live in a subdivison, applying imidacloprid to the turf to kill the grubs will have some effect. Pheremone traps are only effective if you have a large property (probably a couple of acres or more) where you can entice them to a far corner, away from your ornamentals. The best thing, if you can reach them, is to pick them off and put them in a pail of bleach solution. By getting to them early, you prevent a mob attack.

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Pasadena, Md: For the first time ever, we have had some success with growing watermelons. We have crimson sweet and sugar baby varieties. How can you tell if the watermelon is ripe? We had read and heard of the tendril opposite of the watermelon turns brown and dies that the watermelon is ready but the watermelon we picked using this method had flesh that was just slightly pink.

Adrian Higgins: I'm quoting here from Taylor's Guide to Heirloom Vegetables: The spot where the fruit rests on the ground should be yellow, the tendril you refer to should be shriveled, and the melon will make a holow "punk" sound when you rap the rind with your finger tips.

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Vienna, Va: Hello,

I have creeping petunias in hanging baskets on my balcony that I planted in May. The flowers have been full and spectacular; however, they lost that full look because they are only flowering at the tips. I was wondering if I cut them back will they regrow and flower all over again? Thanks.

Adrian Higgins: Cut them back and fertilize. This is a good trick for containers when you are about to leave on vacation. I wrote recently about hanging baskets and how they need watering daily.

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Linden, Va: Adrian - What is the carrot planting strategy for this area? Plant in early spring and late fall or can they be planted all summer long? I planted some early this spring and let them go too long so they're not very tender and I'm ready to try again.

Thanks!

Adrian Higgins: Sow them over the next month for a fall harvest. You really have to thin carrots to get them to develop correctly, and it's a laborious chore but it makes all the difference. I cover the seeds with a light potting mix because any crust that develops on the soil will inhibit seed growth.

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Annapolis, Md: Hi Adrian - I was in Rehoboth last weekend and saw a tree, maybe 25 ft. tall with white flowers, very fragrant. My dad called it a honeysuckle tree. Do you have any idea what this might have been? I'd love to have a tree that blooms mid-summer - thanks!

Adrian Higgins: It's a lonicera species that is rather junky, soft wooded and tends to seed. I would avoid it.

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Silver Spring, Md: I have a container garden, and my potted herbs look very anemic after all of the heavy rains. I'm assuming that the rain washed away the soil nutrients. Is there anything that I can add to the soil now? (I would prefer organic as we do eat the herbs.) Many thanks.

Adrian Higgins: For certain herbs that lend themselves to trimming, such as mint, basil, oregano, even sage, I would cut them back by about a half, and then give them a gentle feed with a fish emulsion or seaweed fertilizer.

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Silver Spring, Md: Prof. Higgins, Question about zucchini: I have one plant that seems to be growing very well, with big leaves and many flowers. Right now there are about 4-5 small zucchini growing. Oddly, the 2 oldest fruits have seemingly stopped growing (maybe even be shrinking) and are turning yellowish. What can I do to keep them growing? Thanks

Adrian Higgins: Assuming this is not a yellow fruiting variety (and even if it is)you have to keep harvesting for it to keep producing. If the fruits are under assault from pest or disease, destroy them and keep the bed clean.

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Fairfax, Va: Adrian,

What can I plant to attract hummingbirds ?

Adrian Higgins: Salvias, monardas, geraniums, impatiens, agastache and cardinal vine. And a veggie called Scarlet runner bean.

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Alexandria, Va: Good morning, Mr. Higgins!

Several years ago I bought a plant called coralberry at a Virginia native plant sale. It is doing well - spreading out and growing. However, it has never flowered or gotten those "coral berries". When should I expect a little color from it? Thank you so much for doing these chats!

Adrian Higgins: If this is Indiancurrant, Symphoricarpos orbiculatus, it should set fruit in the fall without needing cross pollination. Perhaps yours is too young, or you are pruning the flowering wood in late spring as it prepares to grow.

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Washington, DC: I had a box turtle show up in my Capitol Hill Courtyard out of the nowhere about a month ago. He seems to like it back there but I've found no consensus on whether he's making it okay, as in do I need to supplement his diet?

Adrian Higgins: I suspect the large slug population in the wake of the storm will keep him happy. Does anybody else have any advice?

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Fairfax, Va: Adrian,

About the blue rose. There is a Japanese company working on one, but not as yet.

As far as what everyone else calls blue, it is merely lavender. Truth in advertising.

Adrian Higgins: I'm right! Bliss.

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Yellowing tomato leaves: Adrian, I have some better boy tomatoes planted in large (15" diameter) pots on my deck (potting soil, manure, peat moss, and sphagnum moss). In the last week, the bottom leaves have started to yellow, and the stems are easily pulled off. I am watering every day or every other day, and use Miracle Gro about twice a month. What's going wrong?

Thanks

Adrian Higgins: You're probably getting a condition called early blight, which is spread from spores in the soil and works its way up the vine. It is important to remove the diseased leaves and then not to touch healthy foliage. A thick organic mulch will reduce the spread of this disease.

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Japanese Beetles: Apply Bayer tree and rose systemic in the spring. Works for 12 months and has kept them off of my hibiscus, tea roses, and weeping cherry.

Adrian Higgins: I generally don't like chemical controls but this beast is so pernicious, sometimes that's the only solution.

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Del Ray, Va: Hi Adrian,

Many thanks for your advice!

What plants should I be planting/starting for my vegetable garden at this point? We have potatoes/summer squash/beans/tomatoes/cucumbers/peppers/eggplant and watermelons going right now. What else should one plant to acheive a "year-round" rolling harvest? Any books you can recommend on the topic?

Thanks!

Adrian Higgins: I would think about fall salad greens, another crop of beans, carrots, broccoli and brussel sprouts, and loads of Asian greens, as well as turnips.

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Durham, NC: Hello Adrian,

You may recall that I had a question a few weeks ago about pulling up poison ivy in my new backyard. I'm happy to say that effort was a success; although there is still poison ivy in the lawn, it's kept in check by regular mowing, and the pesky bits that were infesting the surrounding groundcover and climbing trees are now gone.

Now I have a new challenge: finding plants that will tolerate partial shade and that won't be a deer magnet. I planted some impatiens, but deer (either deer or rabbits) ate them all, without leaving a trace. I bought some gorgeous coleus at a farmer's market, but I have yet to plant it. If you think these would be vulnerable to deer-snacking, I will just put them in a hanging basket. Also, are coleus winter-hardy at all?

Thanks in advance for your help!

Adrian Higgins: Coleus wouldn't be winter hardy in Durham. Can you put out a sacrificial plant to see if they will eat it? What I would suggest is going to Plant Delights Nursery near you and see what they have in their display gardens that is deer resistant in shade.

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Madison, Va: Thanks for all the tips! I have always had a vegetable garden, but in my new house I have very limited direct sun, 3 to 4 hours max per day. Do you have any recommendations for vegetables that will thrive in such an environment?

Adrian Higgins: Very few. As my gardening friends in England would say: You're making a rod for your own back. Even lettuce and parsley needs some sunlight. You might try these, but I'd be inclined to plant a shady groundcover or ferns instead.

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Ashburn, Va: Are there trees or perennials that you think gardeners should use more of?

In the neighborhoods in my area, we all seem to use a relatively limited palette of plants in our yards.

Are there plants that you pine to see more of?

Adrian Higgins: I think there are lots of woody plants that have not been given their due. WHenever I visit the Asian collection at the National Aboretum and see the Camellia oelifera, I am amazed that we have not been growing that like mad. It makes a gorgeous small tree with time, and with a cinammon bark that rivals that of the strawberry tree. Also, the pseudocydonia and parrotia are two trees that need to be grown more.

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Bethesda, Md: For the first time in years I am having a terrible problem with chipmunks destroying my veggies. They killed by pole beans by biting through the stems at about 5" and dine daily on male and female zuke/yellow squash/pumpkin buds and flowers. I don't mind living in harmony with these and other critters, but this is getting very frustrating.

Thoughts welcome!

Adrian Higgins: I don't know what to say. I hate squirrels but I love chipmunks, and I put with them for that reason. I couldn't bring myself to trap them. Does anyone have any answers?

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Washington DC: I have about 20 large old boxwoods in my yard. About half of one of them has gradually turned yellow then brown since early Spring, and it is now losing the brown leaves. I have been told from different sources that it is boxwood cancer, a root fungus, or spider mites. I'm confused as to how to tell exactly what it is and how to treat it. I don't want to lose these big old boxwoods.What should I do?

Adrian Higgins: Boxwood die from a number of pests and diseases but there are a few things to do that keep boxwood healthy or give them a fighting chance: Plant them in a bit of shade, particularly a place where they will get shade in the winter; don't plant them too low in heavy clay, they hate waterlogged soil, and mulch them lightly. A thick mulch will kill them.

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Suburban, Pa: My condo complex is completely infested with skunks. I think they are attracted to the same slug population as that box turtle...

Any ideas of what I can plant that might help deter them? I've heard lambs ear, but I was hoping for some flowers in my tiny little garden!

Thanks for any help you can provide.

Adrian Higgins: I would ask the management to apply some of the condo fee to getting rid of them.

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Lorton, Va: Hi Adrian,

Could you please tell me what the tree is that has the fuzzy pink balls all over it? I see these everywhere along the highway and in yards. The fuzzy pink balls have been out for about a month. I would like to plant one of these in my yard, could you please tell me what type of situation it needs?

Thanks so much!

Adrian Higgins: This may be the mimosa tree. I'm sorry I hate this thing, its color is a dirty pink, the tree is messy and seeds all over the place, and it is soft wooded. It may also be an invasive exotic. Yes, the hummingbirds like it but I would like it to be visited by another kind of Hummer.

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Madison Wis: Another pest problem.

My daylilys seem to have something attacking them. When the buds open, the flowers look like they have had something eating at them. I am also noticing that it looks like they have black pepper sprinkled on the buds/flowers.

Any idea what is causing this damage? And, what can be done about it?

Thanks, again.

Adrian Higgins: This may be thrips, which are tiny, elongated insects that feed off daylilies. Some form of system pesticide may be in order. Try spraying first with a horticultural oil.

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Rockville, Md: Prof. Higgins, We recently moved to a new home with a crab apple tree. I just discovered it has apple cedar rust. Almost every leaf is covered in yellow-orange spots. I read that the only treatment is a fungicide cocktail applied in early spring or removal of the diseased cedar(s) within a 1/2 mile radius (not practical). Is there anything that can be done between now and next spring?

Adrian Higgins: Certain varieties are more prone than others. My advice is to select crab apple varieties very carefully. It may be that this year's odd weather contributed to the rust. See what happens in the next year or two. If it still gets rust, I would chop it down. This fall, make sure you clean up all the fallen leaves.

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Arlington, Va: Adrian,

I have a 10 year old concord grape vine that in the last couple seasons does not produce well. Many of the grapes ripen and fall off very early and small. I inherited the vine and know very little about what is required to keep it in top shape. Are there basic things i should be aware of ? Thanks.

Adrian Higgins: Grapes benefit from thinning. You don't need to thin every berry cluster, but remove entire bunches at flowering time or shortly afterwards. The ones that remain will be larger. I would also spray it with a copper fungicide against mildew and rot.

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Hyattsville, Md: My curly leaf parsley has been sulking - little growth, some yellow stems which I removed. It is in a large pot with fresh potting soil and chives and flat leaf parsley that are doing fine. Any ideas what I can do to help it thrive?

Adrian Higgins: Parsley is a biennial and may be getting ready to flower and die. Or the wetness of late may be the culprit. I think I would buy some fresh plants and start again, making sure they have good drainage and some afternoon shade.

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Box Turtle: In response to the Box Turtle question earlier . . . I had Box Turtles in my back yard as a kid and they will eat just about anything. They are used to roaming over large areas scavenging for food, so if you plan on keeping it, be sure to feed it occassionally. They love fruit, and if the supply of insects/slugs in your back yard dwindles put some raw ground beef or other meat out because it needs protein in order to bulk up for its winter hibernation. Have fun.

Adrian Higgins: I thank you. The box turtles of the world thank you.

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Lovettsville, Va: Adrian - my fruit trees are looking a little tired. Yellow leaves, slower growth. Should I fertilize? They've been kept pretty well watered.

Also, my weeping peach is looking a bit withered. Again, do I need to fertilize?

I planted these last fall with some slow-release fertilizer. Thanks!

Adrian Higgins: You may be watering them too much. Check the soil moisture and give them a break from the hose.

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Arlington, Va: Hello Adrian,

Can you please recommend a (low maintenance) house plant or two that would work well in a condo unit with somewhat limited natural light? I'd like to spruce up my bachelor pad a bit. Thanks!

Adrian Higgins: A clivia is one of my favorites, though it takes three or four years to flower.

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Fairfax, Va: I have 4 watermelon and 2 cantaloupe plants growing in a bed. The vines are growing like crazy and have completely covered the bed. Every so often, I trim the ones that cross over into the lawn. I see some tiny watermelons growing. Any advice on controlling the growth and helping the fruit?

Adrian Higgins: You can steer the vine back into the bed. Watermelons are heavy feeders, a sidedressing of compost is good for them as is organic liquid feed. YOu only want a few fruits per vine and should remove any nascent fruit that will draw resources from the keepers.

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overrun with chipmunks: Yes, chipmunks are cute little devils, but when

there are too many (as with any creature), they

can cause problems. For example, they tunnel

under my bricks-in-sand walkway so it eventually

collapses and I have to reset the bricks every

couple of years. You can buy small chipmunk-

sized live traps made by Havahart that you can

bait with peanut butter. Then you can make a

statement by where you release them. I target

Burning Tree Country Club in Bethesda, where no

women are allowed on the premises-not that I

have a burning desire to play golf, but it's a matter

of principle.

Adrian Higgins: So that's why the golfers wear plus fours!

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Central Massachusetts: Despite the bunnies, our squash and pumpkin plants are flourishing. However, I am finding a black and white striped bug on the blossoms. It is not quite a quarter of an inch long and very active. What do you think I have and how do we get rid of them?

Thank you.

Adrian Higgins: This is the cucumber beetle, which not only feeds on the plants but spreads a virus, and should be hand picked for as long as it takes to get rid of them.

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Baltimore Md: Hi, love the chats. Thanks! I have tomatoes with blossom end rot. Tried the egg shells in the soil... still not helping. Any other ideas?

Adrian Higgins: First, remove all the fruit showing this, and then cultivate the soil around the vines to aid in drainage and evaporation. (Waterlogging can cause this). I wonder if the egg shells alone are enough to supply the calcium the plant needs. I would top dress with bone meal.

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Annandale, Va: How practical is it to transplant a large boxwood? I have two American boxwoods that were undoubtably cute 40 or 50 years, but are now about 5 feet tall and wide, and are obscuring the end of the sidewalk. However, it seems a shame to destroy large healthy boxwoods. I'm thinking of advertising them on Craigslist in September, free to whoever digs them up. Or are there landscape/nursery companies that collect established bushes for new owners?

Adrian Higgins: There are companies that will dig them, don't give them away. Boxwood move relatively easily if you know what you are doing. If you see large boxwood installed at a new garden, they are inevitably purchased from boxwood brokers. Find out who the landsscape architect is, and see if they will tell you who the broker is, and then contact them.

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On the subject of trees with pretty bark...: ...and of trees I'd like to hit with a Hummer. I just cut down a mulberry tree in my yard. I'm thinking of replacing it with a Chinese Elm. I want a medium-sized tree that will provide some shade and something pretty to look at. And no nasty berries!

Adrian Higgins: Chinese elms are ok, wouldn't be at the top of my list. What about an American hornbeam?

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Washington, DC: I seem to have a huge infestation of azalea lace bugs, following all the rain. The leaves of my azaleas all turned silvery and there are bugs and black dots (droppings?) on every leaf. I'd rather not use pesticides if I can avoid it. I've just been trying to spray the bugs off with a hose - is this worth a try? what will happen if I don't do anything?

Adrian Higgins: This is most prevalent on plants in too sunny a location. Can you move them to a darker spot? You need to spray horticultural oil on the leaves early in the season, and then repeat to prevent populations from building up.

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Washington, DC: you are so kind to do these chats and help us out like this.

My collards are looking a bit lackluster, a bit too pale and some are drooping and even yellow. I read that maybe they need nitrogen, so I added some amendment. Any other recommendations? Thank you!

Adrian Higgins: The pleasure is all mine. I wonder if a lot of veggies are reacting to all the rain. I would again loosen up the soil around the plant, this will aid in soil breathing and drying out. Continue to feed every couple of weeks with some gentle nitrogen fertilizer, or just a mulch of screened and well rotted compost.

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Aphids and Basil??: What to do? This is the third year now and nothing seems to work. The insecticidal soap deters them for all of an hour or two, then they're back...I've even tried throwing out plants and dirt and starting over altogether, to no avail. Is there any solution to this problem?

Adrian Higgins: If you remove the top couple of inches, that is the lushest part of the plant and the growth they like the most. This will promote a bushier plant. Keep washing them off. Alas, we have run out of time and I am sorry that I can't get to all the questions. Check out Thursday's Home section for lots of great gardening coverage.

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