The Garden Plot

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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Pumpkinland, USA: Dear Mr. Higgins,

We have a single volunteer pumpkin vine now covering at least 100 sq ft of our back yard. The rapid growth of this thing has amazed our family and neighbors, and many small pumpkins are now forming.

If we pinch the ends to tame this monster, would that do any harm? Is there a way to encourage the vine to grow bigger pumpkins?

Thank you!

Adrian Higgins: Before I get to this question I want to thank everyone who emailed me their stories about tomato growing this summer. What a difficult year it has been: In Thursday's Home section, I will be throwing some light on why it went wrong and what we can do next year for a better harvest. On to pumpkins: Three or four fruit per vine is all you want to allow to develop to encourage large and robust fruit. Trim back the tip of the vine to a convenient point, remove any additional developing before the blossom fades entirely and keep the vine well watered. You may also wish to slip a piece of cardboard under the pumpkins to keep the fruits clean.

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Silver Spring, Md: Good Morning Mr. Higgins,

I have a 16' wide, 2-story brick wall that bakes in the hot afternoon direct sun. I'm looking for a vine-type of plant to climb and cover the wall. I've tried a japanese climbing hydrangea for a couple years now, but I don't seem to have much luck. No matter how much I nurture the plant, it wilts almost daily, and appears to get leaf scorch. I think the afternoon sun is too strong. Any other plant ideas? I'd appreciate any insights. Thanks much.

Adrian Higgins: Climbing hydrangea resents such an exposed location. I would consider a rambling rose or, possibly, a hardy kiwi vine. Both will need a system of trellising or wire supports before you plant them. Support them as they grow.

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Charlotte Hall , Md: I need to re-seed my back yard, lots of bare spots. I have not yet put down seed because of the dry weather and heat, now it is suppose to be a rainy week, I cannot re-seed until the week ends, if we do get lots of rain. How long do I have to wait after the ground gets soaked before can rake and seed the bare spots. I was always told not to work the soil when it's wet. By the way we have a mostly clay based soil

Adrian Higgins: First of all, it's a wee bit early to be seeding, but you are bound to get early germination, which is good if you stay on top of the seedling's misting needs. Second, and I'm sorry, but I no longer believe the weather forecast. I think watching which leg a chipmunk scratches itself with might be more accurate. It will take another deluge to cause the soil to become heavy and unworkable, so don't worry about that.

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Annandale, Va: Dear Prof. Higgins,

I recently saw some non-hairy caterpillars eating the needles of my lolloby pine en masse. I mean these guys were lined right up together, and I mistook them for plant parts because of the camouflage coloring. This way they leave no plant part uneaten as they move en masse. I wouldn't noticed except for the bared limbs, and the residue from the needle chewing on the sidewalk. I cut and bagged. Any idea of what these were?

Adrian Higgins: pines are afflicted by about half a dozen grub pests and none of them portend luck. I would make haste in identifying your pest at an extension office clinic and having it treated.

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Fairfax, Va: Adrian,

You answered my question about splitting cana at the end of the season "when you pull them out for storage."

I don't pull them out. I just cut them down to about five inches tall and mulch heavily around them.

So I guess I can thin them out this fall, eh ?

Adrian Higgins: It's possible with global warming that cannas can now be left reliably in the ground over winter. They will need a healthy winter mulch, which should be removed in April.

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Greenbelt, Md.: Can you compost tomato vines? The plants seem somewhat healthy, but I'm worried about causing blight in years to come if I add them to my compost pile.

Adrian Higgins: I think if they were blighted, I would not, because those spores are tenacious and may well survive the composting process.

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Washington, DC: My winter squash has grown all over the garden. It looks healthy and produces many blossems but rarely produces fruit and what squash it does produce grow about 4 or 5 inches and then fall off. I water about once a week. What do you think is going wrong?

Adrian Higgins: I would think a simple lack of water, if the fruits are falling off. Are you sure you're not seeing male flowers go through their natural cycle? The female blossoms have a swollen base that develop as fruit.

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Palisades, Washington DC: Hi. We moved three months ago into a new house. The builders planted seven medium sized plants -- called "upright steed's holly" -- planted around the air conditioning units. One is completely dried up and brown, although we keep watering it in hopes that perhaps it's not completely dead. Three of the others have patches of dried brown leaves but are otherwise green, and the other three appear healthy. Is there something we can do to improve the chances for these plants, which I assume are to become a border to hide the A/C units? I bought some tree and shrub fertilizer spikes -- should I stick some of these in the ground near the shrubs? Thanks!

Adrian Higgins: You only fertilize when a plant is in active growth. Lots of plants are not in active growth at the moment because of the drought. Water the survivors, remove the dead ones, and sort it out in about three or four weeks when the weather has cooled. It is entirely likely that your contractor planted the hollies too close together and that you don't need more, you just need to reposition them. I don't know what an upright steed's holly is, perhaps you mean Nellie Stevens Holly, which grows to 20 feet and a spread of 10.

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Washington DC: Just moved into a new house and I'm determined to not destroy all the expensive plantings put in by the builder . . . but I don't have a green thumb can't afford a knowledgable gardener to guide me. My question is this: should I be cleaning out any brown/dead leaves that accumulate beneath bushes or shrubs? I've wondered if I am helping or hurting the plants as I do this. Thanks!

Adrian Higgins: Unless they are smothering ground covers, they might help in conserving soil moisture at the moment and would be worth keeping. But do water things deeply.

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Washington, DC: Currently I grow thyme and rosemarry in small pots. They seem to be doing very well with minimum care. Will they last through the winter? What spices and flowers might I be able to grow in the winter?

Adrian Higgins: The plants will do fine, the pots may crack. Spices through the winter? You could grow cilantro with a little protection, and parsley as well. Winter flowering plants include hellebores, witchhazels and wintersweet.

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Columbia, Md: I have peonies and some of them started with white dusty looking leaves and have progressed to very white dusty looking leaves. Do they have a fungal infection? What can I do to stop it or treat it?

Adrian Higgins: It sounds like powdery mildew. Try spraying to contain the disease, or if the leaves are so unsightly, cut them off and bag them. Make sure you clean up all fallen material in the crowns of the peonies this fall.

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Laurel, Md: Hi Adrian, thank you for offering this great chat.

I am a novice gardener. This past May, I planted 6 or 7 big daddy hydrangeas. THey looked healthy for couple months, couple even had a flower or two. However, in August, they started wilting, and now only one layer of green leaves are on top.

I water them every other day, so I don't think it's lack of water. Is this normal? I keep hearing that the first year they don't do too well, I'm hoping that's the case.

Also, what is one supposed to do for plants as fall and winter approaches? Do I keep watering?

Thanks again.

Adrian Higgins: If you are watering them every day, you may be drowning them. Check the soil and see how wet it is. If it's soggy, don't water for a week or more.

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Bethesda, Md: Thanks for taking my question Adrian.

Is now a good time to move a lilac? I know they don't move well, but I have no choice.

Adrian Higgins: I would wait a month, for cooler temperatures and some chance of rain.

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Chantilly, Va: Adrian,

Thanks for your suggestion about the compost tea. I found a site with some very good directions for making it in small amounts.

Adrian Higgins: Great. I keep meaning to making my own, but there are so many other chores at the moment in terms of trying to rescue the plants from the stress of drought and heat.

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Washington, D.C.: I am interested in replacing 2 unhappy Azalea bushes in the front yard of my rowhouse. It is a very sunny spot, can you recommend any bushes to replace them that would give us some cover from the street? Thanks!

Adrian Higgins: I think some of the shrubby, dwarf varieties of crape myrtle would be a good choice for a hot dry site.

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Bethesda, Md: Good morning. This summer I planted three brussel sprout cabbages and they've been growing strongly, if only now they're starting to show the buds. But in the last two weeks or so, they have become a magnet for flies (!). I doubt they're harmful, and the only damage the cabbages show seem to date from an early invasion of cabbage worms that I erradicated, but it sure is nasty when you walk past them (they're on the side of the path to the front door) and all the flies fly around, startled and buzzing. Is there real danger to the plants and, anyway, can I get rid of the flies? Thanks.

Adrian Higgins: It's hot for maturing brassicas at the moment. I hope this is not the cabbage maggot fly, but it may be, especially if it has red eyes.

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Silver Spring, Md: Hi, Adrian, Thanks for doing these chats! The previous owners of our home did a nice job of planting masses of daffodils which are followed by hosta that cover up the yellowing daff leaves. I'd like to do something similar in a vacant flower bed that gets part to full sun. We have an overabundance of hosta. Do you have suggestions for other perennial greenery (flowering or not) that would appear just in time to cover dying daffodil and/or tulip leaves? I would probably plant summer annuals among them.

Adrian Higgins: You may consider the hardy begonia or epimediums, if the site is a little shaded, or asters or coneflowers for a sunnier location.

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Chantilly, Va: Dr. Higgins,

How do you properly divide and transplant? This is the first time I will be dividing hostas, lavender, and day lilies, and want to make sure I do it properly. I will be doing this toward the end of September. Thank you.

Adrian Higgins: You really can't divide lavender, that's best propagated from cuttings. For the others, lift the entire clump and then get a hose and gently wash off the soil so that you can see the parts to divide. Hostas may need a sharp knife to make the separations but I find daylilies are best separated by hand.

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Vienna, Va: Adrian,

I planted morning glorys in late June and I have yet to see one blossom. Lots of green leaves, vines a crawling all over the place, but no flowers.

I'm giving them another ten days, and if no blooms, out they go !!

Adrian Higgins: This is a common complaint with morning glories and I'm wondering if it is in someway related to the high nighttime temperatures of August. If you stay with it, it will bloom in late September and October, I believe. There is something to be said, however, for yanking out plants that are underperforming, it's a form of mental health for the gardener, a way of asserting that the problem is not with the gardener but with the lousy plant.

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Washington DC: Another question for you about fertilizing a new planting: We have a small dogwood that was planted 2 months ago that isn't exactly flourishing, although it doesn't have lots of dead brown leaves. We've been trying to water it frequently in this drought. Would it hurt it to give it some plant food or stick in one of those fertilizer spikes? Many thanks for all your help.

Adrian Higgins: In retrospect, given the heat and dryness of this particular summer, it might have been wiser to plant it in September. I wouldn't feed it now, for one thing you don't want to encourage fresh growth that will be harmed by November frost.

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West Orange, NJ: I am a serial failure with rhododendrons. Every one I plant fairs poorly or dies. Does some prime mix of planting depth, sun, water, and pH assure success? Or are these plants just plain hard to deal with?

Adrian Higgins: Rhododendrons are native to mountain regions where soil temperatures do not get as high as they do on the Eastern seaboard, certainly below New York. The only way to succeed, in my view, is to plant only the few varieties that can put up with these extremes and reject all others, no matter how pretty they look in the nursery in May.

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Bethesda, Md: Adrian,

Help me outsmart our fruit thiefs -- ee have two apple trees and a fig tree all of which started to produce fruit which subsequently "vanished" before ripening. Should I surround the plants with mesh?

Also, when and how is a good time to prune wigelia?

Adrian Higgins: I noticed a blasted squirrel had eaten one of my few ripening apples this morning. I don't know how to cage a lone apple in an effective way. Soft netting would not prevent a squirrel from getting to the fruit, you would have to net the whole tree. If others have solutions, let's hear them.

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Silver Spring, Md: Adrian, Just wanted to share with you and the gang that my crabgrass crop was severely diminished this year. I harvested on Saturday and most of the plants were nearly dead. I suppose I can attribute this to our lack of rain, same as my poor tomato crop. Oh well, it does make them easier to pull when they're half dead.

Adrian Higgins: True, but I suspect they have been seeding for a few weeks and I wouldn't expect an easy time of it next year. I would recommend laying a crabgrass preemergent herbicide next April.

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Oklahoma : I have two pumpkin plants growing in a window sill planter that is sitting on a bench. The ground doesn't have very much nutrients and how can I let the plants live without them becomming rotten in the planter?

Adrian Higgins: Pumpkins are heavy feeders so your only chance, I suspect, is to keep the planter watered daily and given a weak fertilization once a week.

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Frederick, Md: I have a large spruce tree in the front yard (close to 20 feet tall). Last summer it dropped needles heavily on the north side, but the rest of the tree looks very healthy. This summer the needles have come back a little. Any guess as to what's ailing the tree, or how to correct it? By the way, love your segments with David Burd on Saturday mornings!

Adrian Higgins: Spruce gets a dieback disease called leucostoma canker. Watering in drought will help reduce stress. The affected branches won't grow back, because it's a conifer. It is important to remove the affected branches to prevent its spread up the tree. It's fun with David, we're on from around 7 a.m. to 8 a.m. on Saturdays and we love your questions, the number is 1-800-POST-1077.

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Chantilly, Va: Adrian,

I planted a weeping cherry tree two years ago. It's starting to fill out in the branches, but doesn't seem to be getting taller.

The tree is supposed to get to 15 feet, but I'm wondering if it'll be a few more years.

Adrian Higgins: Please be more patient, and please water it, cherries get borer in droughts. Weeping trees, by design, are not so tall and 15 feet may well take 20 years.

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Falls Church, Va: There are a few plants on the side of my yard that need to be moved to make way for some construction. They are all over 10 feet tall and spread about 5 or 6 feet. There is an azalea, some type of boxwood, and a leyland cypress. Can they be moved as early as November and what preparations should be taken now so that they have a good chance of surviving?

Thanks!

Adrian Higgins: I would prepare a bed with deep rich soil, then dig the plants in about a month. You can wrap the rootballs to contain the soil, using burlap, and then place them on a tarp, and drag them immediately over to the holding bed. Give them a thick mulch of leaves. All three plants have shallow root systems and should move well for you.

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Arlington, Va.: Mixed results with the community garden this year. The zukes were huge plants with very little production, same with three varieties of beans. Flowers were hit or miss, and I'm thinking perhaps it's the soil in my plot. (First year so I have no standard for comparison.) What should I add to the soil (now? in a month or two?) to boost it for next year? Thanks!

Adrian Higgins: If you are building soil for over the winter, you can certainly pile shredded leaves over the soil as well as manure, and then use a garden fork to dig them under. You might also sow a cover crop such as red clover or vetch to keep the weeds away, and then turn it over in early March.

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Manassas, Va: posting early because of meeting.

I planted cherry and grape tomato varieties this year. I have beautiful plants probably 8 feet high and loaded with fruit. I noticed a problem with the cherry tomato variety (but not the grape variety) for most of the season. Quite a lot of fruit was splitting on the vines as they ripened. On some occasions I would pick a quart or so of perfect fruit take them into the house and rinse with water and they would split before my eyes. what is causing the splitting in the cherry variety but not the grape? Actually do your readers realize that the grape tomatoes are much more flavorful than the cherry types?

thanks john

Adrian Higgins: I think grape tomatoes are going to become very hot in the next few years, especially with the release of sweet consumer varieties. You may be watering them a little too much, if that's possible. Cut back on watering as they begin to color, and this should minimize the splitting. Well, folks, another chat has come to an end, let's pray for rain. I'll see you on Washington Post radio tomorrow at 11:30 a.m., on Saturday in the 7 a.m. hour, and, of course, in Thursday's Home section.

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