Adrian Higgins gives advice on grooming your garden in the summer

Aug 25, 2011

Learn how three D.C. homeowners share their backyards to create an urban oasis, and get summer gardening advice.

Any suggestions on getting rid of wild violets? I have tried digging them out, but there seems to be way too many.

Greetings, everyone. Thanks for joining us today. Violets seem to be going crazy this year. Given their tuberous nature, I've always preferred to physically remove them than try to use herbicides, which may just kill the top growth. I have used both a fishtail weeder and a pick (actually a mattock) to great effect. Wait until the ground is saturated from a rain, they will come out much easier.

I am having an issue with maintaining both veggie garden and flower beds, (primarily perennials and shrubs) due to invasion of roots, presumably from trees in and around the yard. This is in College Park in a 50+ year-old community with two original maple trees, silver and red, in the backyard and gum trees and oaks surrounding the yard (in other neighbors' yards). Gardens have been installed for over 35 years. The issue arose a couple of years ago; I'm presuming it is from my attempts to keep gardens watered during drought conditions. I have now been dealing with thick mats of hairy roots throughout gardens, which seem to inhibit seed germination and seem to rob the surrounding plants of water and nutrients, killing a variety of perennials and making survival of new plantings near impossible. How do I stop this invasion short of cutting down trees? This past spring I had the two maples in the yard trimmed back by 1/5, maybe. Do I need to attack the roots similarly? Seems like alot of work to dig up all of the beds, replant, etc...

I'm surprised that you have enough sunlight with such root problems, and I'd advise against a lot of work if you don't have at least six hours of direct sunlight. If you do, I would build simple raised beds using pine boards on edge, and backfill with amended soil. You have to first peg weedcloth to the ground before backfilling to prevent the roots from growing into the raised beds. Good luck.

An adjacent county's conservation district is selling tulips. Besides well drained soil where should I plant them knowing these tulips will come out earlier than the tree leaves? Which type to you favor? Do I plant in masses for color or mix with the others. Polychroma is close to daffodils in color: white petals with yellow centers. Sun Lover is red with touches of yellow. The petals are many. To me it looks like peonies. Fantasy is a bright pink with saw tooth petals. Saxatilis is a light pink, yellow centers and, again more like a daffodil but a wider open bloom. Uncle Tom is a deep purple, nearly black, tulip with multiple petals. Flaming Bird is a variegated petal: white with raspberry red saw tooth, petals.

I love tulips but apart from a few species varieties, they're not reliably perennial and the best approach is to treat them as annuals. If you are bothered by the fleeting nature of tulips, I'd advise daffodils instead. I love all types of tulips, in recent years I've been planting a lot of lily flowered tulips, I think they look particularly elegant. This spring I paired white with orange lily flowered. I also like some of the stronger colors. Gavota is a champ. 

Hello. Thanks for doing this chat. Would you please recommend a fairly basic book for indoor gardening, particularly herbs? I have a condo with two south-facing windows, unfortunately surrounded by other high-rises. I'd love to learn about what types of plants grow best indoors and whether the seasons affect them. Thanks!

Generally, herbs are hard to grow indoors because they need light and lots of it. If you have an enclosed porch or a sunroom or something, you can go to town, otherwise your options are not a lot. I'd refer you to the website of the American Herb Society for more information.

Thanks you for the interesting story. I'm not sure that a shared garden like this would work for me--I like my privacy too much! I hope you are able to do a follow up after the house is sold.

Thank you. It was much harder to find shared gardens than I thought it would be. I think people who buy single family homes do so because they want the privacy, as you mention. The neighbors in this case were good friends and two were brothers, it was an ideal set up and I think though the gardens were not professionaly designed, the owners did all the right things to make them work together.

I'd love to compost and I bought a tumbler-type of composter but it didn't seem to work very well. I'm thinking that's because it is in the shade. I don't have a sunny spot for compost in my urban backyard - do I have any options for composting?

Compost piles tend to do better in sunlight, I think the heat encourages the microbes. But I think the problem may be that your tumber compost simply isn't big enough. Compost piles have to have a critical mass, the standard recommendation is one cubic yard of fresh material. They also dry out in our climate, which stops the composting action dead. You have to keep them moist. If a pile has dried and stopped decaying, you can rake out all the material, mix it with some fresh, and give it all a good watering as you put it back. Horse manure will kick start any lagging pile.

Should I cut the dead flowers off of my butterfly bush? I heard the deadheading can force reblooming on the plant.

Definitely. Use pruners to remove fading flowerheads. This not only encourages reblooming, it makes a weedy bush look much tidier. It also prevents unwanted seeding.

Hooray - my toad lilles, planted a couple of years ago, are finally blooming. Should the plants be separated, and if so, when?

Toad lilies or tricyrtis are just coming into season, and have the most amazing orchid like flowers when we most need a boost in the garden. I love them. They are not one of those perennials that need regular dividing and I would only do so if you find an old clump that has become congested. Yours are probably too young for that. They should be divided in the spring, as new growth emerges. They are a woodland plant and it is important to keep them moist during the growing season. (Especially one like this, that was dry in the first half of the summer).

Adrian, is it too late to plant seeds for a fall harvest? Spinach, lettuce, beans, beets, that sort of thing. Thanks Adrian!

It's not too late for lettuce, arugula, mesclun, radishes and other cool season, fast growing greens. I think beets wouldn't work at this point, and beans are running out of time. Your spinach will germinate and produce small plants this fall, but should overwinter and grow well next spring.

Adrian, I'm thinking of making part of my garden a weed garden. I'm planning on planting some Queen Anne's Lace, and a variety of other flowers I see on the side of the road. Is there anything I should be wary of in this approach? Thanks.

You don't want real weeds, i.e. noxious interlopers, you want wildflowers that exist in nature but have some eye appeal. I would consider black eyed susans, coneflowers, joe pye weed, asters, ironweed and the grasses little blue stem and prairie dropseed.

Good Afternoon Adrian. Not on topic, but may I ask a question regarding my kiwi vines? The leaves this year were "speckled" (I think mites? as the same symptoms showed on the boxwood and pieris shrubs nearby). I would prefer a natural approach to control, but am confused about when to introduce a beneficial bug to solve this issue. Thank you for your advice.

Mite damage is particularly obvious in dry years like this one. The best thing is to keep them hosed (upper and lower leaves) but within reason, you don't want to induce fungal disease, and to give these plants a little bit of shade, particularly the pieris and the boxwood. A winter oil might also help in February.

Adrian, Great column on the shared back yards! I hope you'll take an unrelated question. I have no luck growing bell peppers. No matter what variety I try, the peppers are small, thin-skinned, and low-yielding. I'm growing them in my community garden plot; they are in full sun and I've amended the soil with lots of screened compost. What can I do next year to improve my harvest? Thanks.

Generally, peppers need a long season, especially bell peppers, and should be started indoors early so that you have pretty large plants come May when you set them out. They do need a lot of sunlight, which you have, and benefit from mulching to retain soil moisture, and some potassium and calcium feed. For next year, I would consider earlier season sweet peppers that are smaller, such things as Marconi, Golden Baby Belle or Costa Rican Sweet.

About this time of year, some diseases have started to pop up (typically tomatoes and cucumbers), but my plants are still producing. I sometimes trim the affected leaves--is there any point in this, other than aesthetics? Also, if you have any tips for securing my plants against the wind expected this weekend, I'd appreciate it. I plan on building more sturdy trellis next summer, but I need immediate help that won't become projectiles!

I think at this point the tomato vines are long, scruffy and diseased and why keep them going for the sake of a few more fruit when you can pull them, cultivate the soil, and throw in a mesclun mix for the fall. That's what I'm doing on Sunday, Irene permitting.

I have several heucheras, heucherellas, and tiarellas, which I have moved from damp shady spot to damp part-sun spot and they just sit there. They don't die, but they don't grow and they don't bloom. Is there a particular type of soil that they favor? What am I doing wrong? (And I don't move them often, have only moved them twice over seven years)

Heucheras are maddening plants. They look so beautiful in the nursery and they last a year or two in the garden. The problem is they hate wet winter soil. One thinks of them as woodland plants, but they really dislike any sort of heavy clay soil. Villosa hybrids are less fussy.

Dear Adrian, I desperately need your wisdom! Our lawn is a mess. It is more weeds than grass and a vast variety of weeds, at that. What can we do to restore it? Does it need to be completely torn up and replanted? Or would using roundup to kill the weeds, followed by aeration, seeding, and fertilizing be enough of a first step? Signed, Sick of Being the Neighborhood's Worst Yard

First of all, I'm a big fan of seeding over sodding. And we are approaching the optimum time for seeding (October).  If your lawn is ready for a major renovation, you could spray it now with Roundup, again in a  couple of weeks, and in late September get to work. If you don't want to use Roundup, you can devote the next two or three weekends to getting out there with a shovel to skim off all the old vegetation. You'll need to add some topsoil/compost, cultivate the soil, sow and press seed (turf type tall fescue) and keep it moist for a month or so. It's not that hard, but it is a methodical commitment. Worth it!

I know that true clover is good for soil, but I've noticed more and more oxalis in our lawn; is it beneficial too, or do I just shrug and thank heaven that it's green? Or try to get rid of it?

Oxalis is horrible and won't stop germinating. I just keep pulling it before it goes to seed. Again, weed work a day or two after a good rain is the way to go.

Professor Higgins: I am thinking about planting two autumn blaze maples about 30 feet from my house, surrounding a deck. I like them because they grow quickly and seem to be good shade trees, in addition to growing in so-so conditions. Any reason why this would not be a good choice, or is there something better? Both would get about 5 hours of good sun a day, but are also shaded during the early morning and later afternoon. Thanks!

No I think these would be good shade trees, recognizing that if you get bitten by the veggie garden bug in three years, you'll have to find somewhere else to raise your edibles. There are several fine varieties of red maples (some sources list Autumn Blaze as another species), so plant different varieties. Autumn Flame is a good one, as is Sunset.

To piggyback on the previous question, is it too late if you plan on using row covers, plastic greenhouse covers, etc.? I find the summer to fall transition my biggest challenge in gardening, as I just can't get the timing right. However, I had several crops overwinter in my plastic greenhouse during "snowmageddon"--under three feet of snow!

I was referring to crops planted openly. Row covers will give you a few more degrees of frost protection, and may get your lettuce through to January instead of December, for example.

Hi Adrian, I have a bag worm infestation and am looking for some advice on how to deal with them as non-toxically as possible since everything I've read seems to be involve far more pesticides than I'm comfortable with. Any ideas?

First, avoid plants that attract them (like leyland cypress), second pick off the bags before they start chewing on the foliage.

I'll be in the DC area around 8am Sunday. Plant Saturday.

Here we go. Maybe i'll attend to the garden on Saturday, though I'm going to the DC State Fair for a little while. Yes, there is one.

Weeds have taken over my backyard, including the patio area, which is paved with stones. The weeds have grown up in between the stones, and I've tried to pull them out, but only ended up breaking them close to the base of the roots. How do I get the rest of the roots out? Some are as thick as 1/4 inch and are extremely stubborn.

You could use a powerful herbicide, or you can get propane burning weed flamers that do a pretty good job (If you're careful). Check out Gemplers or Leonard's.

Should I deadhead my Sweet William?

Sweet William are biennials, so they won't flower again. You should be planting seedlings now for next year (same as foxglove). Or, if the seed is ripe, sow it for to germinate in the spring.

Hello, Adrian--i had the strangest veggie garden this summer. Everything is about fairy size. My Juliet romas are the size of grape tomatoes, my Cajun bells are about the size of walnuts, and the corn never got bigger than cocktail-size pickled corn. What did i do wrong? i even had compost, but maybe it wasn't really "done"? it seemed crumbly and black, or maybe i didn't use enough of it. Anyway, I planted spinach, arugula, mustard, and fennel last night, so maybe i'll have better luck with fall plantings.

Lack of sunlight can stunt veggies, so check your light conditions. Another factor can be lack of moisture. We really did have it dry until recently at a crucial time for summer vegetables. The heat this year was brutal (on plant and gardener alike).

We have a south-facing concrete garage painted white, where we plant our tomatoes and herbs. It gets full sun basically all day. Would it be possible to espalier a Meyer lemon against it? Would it survive our winter? We're in Ellicott city.

'Fraid not. Global warming isn't that advanced yet. Established citrus trees can survive a little frost, but not our winters.

Last year I had tiny little beetle-looking insects that bored into my turnip roots. This year they are into the radish roots and they are starting into the beets. What can I do to rid my garden of this pest? I circulate the plantings in my raised beds so the beds don't hold the same plant 2 years in a row. Thanks!

This is the work of the maggot fly. You're doing the right thing with crop rotation, but obviously it's still a problem. I could tell you to create some sort of soil barrier, which can be successful, but the better course is to avoid planting root vegetables and cabbages for a few years. You could try growing radishes and turnips now rather than in the spring, and see if that helps.

Over the past year, we've reclaimed the yard in our new home from ivy and weeds by pulling them out (without using any chemicals or sprays). Now they are all growing back, and with the recent rain they've been popping up faster than before. I finally think it's time to use a good weed killer but I don't want to harm my other plants (liriope, crepe myrtle bushes and tree, japanese maple tree, burning bush, arbor vitae, etc.) in doing so. Do you recommend any specific sprays or tools to get rid of these persistent, invasive weeds? Thank you.

I'm a great believer in handpulling weeds, and believe they can be defeated for the most part if you are out there once or twice a week. We're out of time, but thanks for your questions. I'll be back in about a month. Happy gardening!

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Adrian Higgins
Adrian Higgins is the Washington Post's gardening columnist. Read his latest story on turning shared yards into an urban oasis, and watch his latest video on preparing a lettuce garden for the fall.
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