Bulletproof roses

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Adrian Higgins
Washington Post Gardening Columnist
Thursday, June 17, 2010; 12:00 PM

Washington Post gardening columnist Adrian Higgins was on line Thursday, June 17, at Noon ET to talk about new, disease-resistant roses.

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Arlington, Va.: Just how low maintenance are the new roses? We don't have a lot of time to spend in the garden, but I am bored stiff by the enormous hedge of azaleas that grows in front of our house. But they are very low maintenance, so there they stay. How much care do these roses need?

Adrian Higgins: Hi, everyone. It's really important that you pick the RIGHT variety, which is why I took pains today to direct folks to these specific roses. I have grown some of them, but not all by any means, so I am commending a bit on faith. But Peter Kukielski at the New York Botanical Garden is not going to put his reputation out there for roses that are dogs. He also grew some in Atlanta, which is blackspot heaven.

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Fairfax Va.: I follow your Ground Work blog every Monday. It is great to have a vegetable garden blog that is local to us. I planted quite a few heirloom tomatoes this year. Both Cherokee purple and gold medal have cat faced fruits at the moment. Do you usually let cat faced tomatoes ripe? How do they taste compared to not misshaped fruits?

Adrian Higgins: At this point in the season, I would remove them without any hesitation. This will encourage new fruit.

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Alexandria, Va.: I have two beds of knock out roses..love them! Only they are attacked by a leaf-eating pest (aphids, most likely) every year. We must spray every two weeks and they still get eaten. Any suggestions?

Adrian Higgins: They might get a little chewed from sawflies, but they are vigorous enough to outgrow that. I would try not spraying them to avoid killing beneficial insects that will go after them.

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Arlington, Va.: Hi there. Would you have any recommendations for a rose that would be similar (in look and fragrance) to a Fragrant Cloud? In your gallery, Rosanna looks good, but is it fragrant? Thanks!

Adrian Higgins: Few of these roses are terribly fragrant. That's the last nut to crack. Sunny Knock Out is supposedly fragrant, as is the climber Jasmina. I am sure that will be a trait that will now be drawn out in the years ahead.

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College park, Md.: Hi Adrian,

I really enjoy the "Groundwork" posts in the "All We Can Eat" blog. Looking at last year's posts, it seems you didn't harvest garlic until early August. My garlic that I planted last fall is starting to yellow now, and many web sources indicate to pull it when the foliage is about half-yellow, half-green. Also, the Grow It Eat it site by the UMD Extension indicates harvest for garlic in Central Maryland is around July 1.

So, I am thinking of pulling my garlic in the next week or two, though I wonder why this contrasts with your August harvest last year. I do have both hardneck and softneck varieties, and some have yellowed more than others, but all are showing at least the start of some yellowing. I did pull a plant last week as a test, it had bulbs formed and are of decent size.

Thanks!

Adrian Higgins: Garlic is beginning to yellow now, a sign that the bulbs should be harvested. This is a gradual process and permits the harvesting of garlic over several weeks. July is usually the peak period for taking garlic. Remember to let the bulbs dry in the sun for a day or two, to cure, and then knock off the dried soil. Don't wash it off.

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Charlottesville, Va.: Have you any recommendations for roses with a strong scent, particularly climbers?

Adrian Higgins: There are many heavily fragrant climbers, the difficulty is that they are once blooming and disease prone. Among this new group of disease free roses, I would seek out Jasmina, Kordes Golden Gate, Laguna and Kordes Moonlight.

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Silver Spring, Md.: Hi Adrian, thanks for taking our questions. You touched on this in your recent column, but what is up with those pesky whiteflies? This was a completely new pest to me last year -- my first year gardening in MD, but also the first time I tried to grow kale and broccoli. I didn't even realize how much damage they were causing until it was too late. I ended up giving up on the broccoli altogether once the harlequin bugs moved in. This year I've been able to salvage some kale by interplanting between arugula (which they don't seem to like) and picking leaves early and often. But I'd like to give broccoli a go again and try cabbage this year too; is it a futile effort? Do those sticky traps really work?

Adrian Higgins: I have found whitefly to be highly localized by garden. Yes, they can be a real problem for brassicas, and they seem to overwinter no matter how cold it is. I have had luck with yellow stick traps. I like to go out and clap my hands so the devils fly off the veggies and alight on the yellow card. Cruel, but it works. If I have a serious infestation I think I would consider buying some predatory wasps (encarsia, maybe?) to deal with them. Anyone else got ideas?

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Washington, D.C: Novice gardener here. Just planted a "Double Knock Out" rose in my front yard a few weeks ago. It was covered with blooms when planted but after the original blooms faded there are no signs of new buds. The plant gets full sun and I have been watering conscientiously --the leaves look fine, just wondering if there's anything I can do to get it to bloom again. Thanks!

Adrian Higgins: There is a lull with Knock Out between blooms, just be patient. A little balanced feed might help.

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Easy Care roses: Good morning, Adrian. I enjoyed seeing the variety of roses suggested for easy-care roses. It is very distressing for a rose lover like myself to go to a nursery these days and see nothing but Knockouts and Carpet roses. Nothing against them, but I'd like more of a choice. One of my other concerns about the "easy care" route is that scent seems to have gone by the wayside. If people would get over the notion that roses must bloom all the time, there are a lot of once bloomers that are very healthy and fragrant. I have two Paul Barden Marianne roses that are covered with beautiful fragrant blooms for about 4 weeks in the spring, and the rest of the summer have nice pretty foliage. They're mixed in a garden that has other things blooming in the summer, and they blend in nicely. That's just one example. I've pulled out a lot of roses that don't work - I don't spray - and am finding those that do work and have healthy foliage, attractive blooms, and, if possible, good fragrance. It would be nice if local nurseries would educate themselves about what works in the locality they serve.

Adrian Higgins: Thank you, that's useful and interesting.

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Richmond, Va.: I have a five-year-old Knockout rosebush that bloomed beautifully this spring. Upon seeing some insect activity, I sprayed a rose insect repellent on my bush early in the day. The next morning, ALL my blooms were wilted and now the green leaves are dropping. How does one control insect activity without "killing" a Knockout rosebush?

Adrian Higgins: Sounds to me as if you used a sprayer that had previously contained an herbicide. Moral, keep one sprayer for herbicide and the other for everything else. Super Moral: Stop spraying pesticides. If you are growing plants well, using compost and not using pesticides, most pest and disease problems will be minimal or controlled by other organisms.

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Part shade evergreen screen - Bethesda: We planted some cherry laurels for wintertime privacy screening -- once the leaves drop, headlights for cars on the somewhat busy street behind our house shine into our living room. We were told these would grow about 8-10" a year, up to 10-12' tall. They don't appear to be growing at all. We aren't really fans of arborvitae. Any suggestions? They get full sun until about noon, then mostly shade (and mostly full sun until about 3 p.m. after leaves drop).

Thanks.

Adrian Higgins: You might need Skip laurels, or I would consider Hicks yew or even some of the new faster growing boxwood varieties. In a bit of shade, camellias might work as well.

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Green Bay, Wisc.: I was told that if you put Epsom salt into the soil in spring it gives it a jolt start. What do you think?

Also, I can not find your article only this Q & A.

washingtonpost.com: Here's the story on disease-resistant roses: http://www.washingtonpost.com/wp-dyn/content/article/2010/06/15/AR2010061504325.html

Adrian Higgins: Epsom salts put magnesium into the soil and help with vigor, flowering and disease resistance. But just a cup, don't go mad.

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Alexandria, Va.: We have some large azaleas surrounding a sunroom that we'd like to replace. I was thinking maybe some kind of shrub rose, but any other ideas? The area gets direct sun from about 1 to 4, with shade to dappled sun in the morning and evening.

Adrian Higgins: That would be a perfect alternative. When you think about it, what other shrub blooms for so long as a rose? I would check out the website of Conard-Pyle (Star Roses), which will give you some variety ideas, though they only sell to the trade.

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Washington, D.C.: Hi Adrian, this is a very timely discussion as my neighborhood is thinking about drought- tolerant plants that could be planted in a street median. We are planning some super- tough plants like Russian sage, but would like to include roses if we can to have a bit of a wow factor. We have knockout roses in our yard and the best part is that they bloomed from the beginning of May until about Dec. 10. Are there good roses that could survive street median conditions - combining drought tolerance with a long blooming period?

Adrian Higgins: Yes, but I think you would need low growers, which would also need to be cut back in late winter. Check out Meilland Drift Series roses.

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Fairfax, Va.: I am a rose lover but I had a difficult time fighting black spot when I was growing just hybrid tea roses. A few years ago, I finally got rid all of them and bought myself some hybrid musk roses. They are fantastic shrub roses with amazing fragrance, and they are resistant to black spot. Even when they do get it eventually in late summer, they seem to survive it pretty much intact.

Adrian Higgins: Yes, a good approach. Another is to use rugosas.

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North Potomac: The weather conditions that promote Black spot in this area are also prevalent in other countries such as India, New Zealand, China, South Africa, and especially England.

Warm, moist days and cool nights promote Black spot but the countries mentioned have developed many rose varieties that don't seem to be as prone to Black spot as common varieties in our area.

Are any of your bullet-proof varieties from these other countries? And why haven't we seen Black spot roses from these countries sold here?

Adrian Higgins: Many of the roses were developed and tested in Continental Europe, though I would say the black spot pressure here is even worse. Look for ADR winners, which were tested in 11 locations in Germany over three years with no spray at all.

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Vienna, Va.: Any suggestions on a rose (climbing or bush) that I can put in front of a two-board fence? They would be in a location that gets 6-8 hours of pretty intense sunshine and next to a busy road. I'd like something fairly hardy that would bloom regularly. Thanks.

Adrian Higgins: I'm almost out of room in my garden for climbers, but I would love to try that Rosanna, and may well find a spot for it.

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Washington, D.C.: I planted my knockout roses last fall, and I got a first bloom this spring, and am now in the middle of the second bloom. The weird thing is (or maybe this normal?) the bushes sprouted some very tall new growth, which is where the second bloom is happening, so the original shorter rounder part is all green. It sort of looks like two plants -- any way to get a more consistent look?

Adrian Higgins: No, that's the habit of the plant, that's why it blooms successively. You can thin out the branches, and should do so in late winter, to give it a less congested look.

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Alexandria, Va.: Soapy water is often an effective homemade insecticide you can use before resorting to pesticides. A tablespoon or two of dish soap per quart of water is a good rule of thumb; just put it in a spray bottle and it won't hurt the plants.

Adrian Higgins: Yes, my mother used that against the aphids, and it was most effective.

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Washington, D.C.: My favorite roses are the ones that grow in my neighborhood. All kinds of colors and fragrances. They have a short blooming season, but they thrive on cigarette butts, dog pee and shade. Propagation requires a simple clipping and a little potting soil.

Adrian Higgins: Can we get the coordinates? (Just kidding).

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Wilmington, Del.: I replaced one of my regular roses last year with a Knock Out and I love it. Now I'm dying to replace the rest; can I do it now, or is fall better, or should I wait until spring?

Adrian Higgins: You could plant a container grown rose now, keeping it watered and mulched. Many of these roses (especially from Canada) are shipped in the off season bare rooted. They have to be planted fairly quickly to avoid root desiccation.

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North Potomac: Where can one obtain a full list of your favorite 100?

Adrian Higgins: It's not my list, it's Peter Kukielski's. I'm not sure it's available yet but when it is I'll post it on my Twitter incarnation (posthiggins).

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Epsom Salts?: This makes sense. Am wondering now if you could make a weak solution and use it as a one-time/once-a-year application for container plants? What do you think?

Adrian Higgins: Absolutely, but in the spring before new growth.

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Washington, D.C.: Where can I find the "Sunny Yellow Knockout Roses" in this area? I haven't seen them in the big-box stores yet.

Adrian Higgins: I wouldn't count on finding them at the "Big Box Stores", where I can't even find organic fertilizers or sprays. I would check with good local independent garden centers and, failing that, check out the mail order sources that I list in the article.

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Shrub question: Adrian, Thank you for your amazing work. I bought a house last year and have been slowly fixing the yard which was quite a mess when I moved in. We live next to a house of renters and there is an 8-foot tall stand of trees and shrubs that separates the front yard. This privacy shrubbery is incredibly overgrown to the point where it probably all needs to be removed and replanted. However, I'm not excited about removing the only real privacy barrier I have between the two properties. I'm also certain the folks renting would strenuously object to trimming them back as far as I'd like to. What can I do in this situation to tame the shrubs?

Adrian Higgins: It's hard to say without knowing what the plants are. If they are conifers, you probably can't do much chopping back. It is amazing how quickly certain plants will grow, given sunlight and decent soil. I'm thinking of things like upright hornbeams, various hollies (Burford, Nellie Stevens, Fosters), chindo viburnum. In a couple of years you wouldn't miss the loss of the existing stragglers.

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Alexandria, Va.: We had a honeysuckle plant in our yard growing up and the smell is one of my favorites of the late spring/early summer. Now that I own my own house, I'd love to have a honeysuckle plant, but I have no idea how to start one. Can they be purchased like any other plant? (I feel like I only ever see them growing kind of wild, not entirely on purpose.) Do they need support like a trellis or a fence?

Adrian Higgins: The one growing wild (Hall's or Japanese) are invasive, and you don't want those. There are decorative types, such as Lonicera sempervirens (various cultivars). They're yummy, though a little aphid prone.

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RE: Skip Laurels: We planted a similar screen of skip laurels along side a busy street to block light, etc. While they grow fairly regularly, they also seem very prone to black spot, powdery mildew and winter damage. Granted this past winter was tough, but we've been battling the black spot and resulting leaf drop for months. They seem a little better now, but be careful.

Adrian Higgins: Thanks for that. They would benefit from a little shade and they don't like drought at all.

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Upper Marlboro, Md.: How to care for iris plants which bloom in early spring only? Should I cut down stems after blooming? I have no color in my yard after iris bloom. Can I add hydrangeas next to iris plants to add color in front yard? Are they compatible? If not please suggest other plants that are compatible.

Adrian Higgins: Bearded iris don't like a lot of competition. You could grow them close to other long flowering perennials such as Russian sage, coneflowers and asters. I can't imagine they would work well with hydrangeas. Bearded iris want well drained conditions, hydrangeas are thirsty fellows.

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Anonymous: You said no to pesticide, but does an insect-killing soap count? It says it's okay for organic gardening on the label. Is this different from pesticide? Also, it has the added benefit of smelling like doughnuts.

Adrian Higgins: What flavor? That would clinch it for me. Seriously, though, organic pesticides are still pesticides. They are less effective (which might be good), less residual (very good) but they still have the potential to kill beneficial insects, such as predatory wasps and flies and pollinators.

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Brooklyn, N.Y.: I have a glorious blueberry bush, which is the pride of my garden. But I've noticed little ants crawling on the leaves and some branches. Not a lot of ants, and I can't see much damaged caused by them. Still, I don't know of and benefit ants contribute to. Do I need to do anything, or just let it be?

Adrian Higgins: Let them be. The only harm that ants do, is they farm and protect aphids. But they are fascinating creatures and deserve a much better press. (Ok, not fire ants).

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English Ivy: Whoever owned my home before me LOVED English ivy. The stuff is everywhere and was starting to climb trees, etc. I've been clearing out as much as I can by mowing it down and then using a rototiller to help loosen the soil so I can pull as much of the vines as possible. I've then been putting down weed mat to try and discourage new growth. I'm winning, but there are still places where this stuff comes back. Are there any products that would keep new leaves from forming or simply kill it without resorting to scorched earth?

Adrian Higgins: You can spray triclopyr to kill the top growth. I have found that ivy vines can be pulled by hand, and they yield better on wet soil. Just make sure you wear gloves and boots etc., to protect against thorns, poison ivy, tools, and mosquitoes. I cringe when I see people gardening in flip flops and the like.

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Arlington, Va.: Do you know of any good books for indoor gardening? I am limited to this and need all the help I can find. What I have planted either dies or gets infested with hundreds of white flies. Any help would be appreciated. Thanks!

Adrian Higgins: I like, if you can find it from an online used book seller, House Plants by Paul Williams (DK publishing)

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Arlington, Va.: Adrian - the article on roses was very timely for me. I recently planted a disease-resistant rose which is doing beautifully, except that insects attack it at night. The bugs in question are small and shaped like a coffee bean and are about that same size. These bugs also love my basil plant and chew the leaves to the point that every year I lose my basil before my tomatoes come in. I have a lot of birds, bees and my two dogs in my yard and am reluctant to use pesticides. So far I've resorted to covering up the rose each night but it's getting too large for that to be feasible on an ongoing basis. Please help!

Adrian Higgins: You shouldn't have to cover up plants at night against bugs. Cutworms and slugs are nocturnal pests, but manageable. I have to believe if you give the plants optimum conditions and soil, you won't have these problems.

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Raleigh, North Carolina: You can not be serious about the disease resistance of the Knock Out rose. I am in constant battle with black spot on my Knock Out roses "Radrazz" which are about 3 years old, planted in constant full sun and purchased from a very reliable, locally owned nursery. While very beautiful when in bloom, I think I have spent about $60 on chemicals trying to keep these bushes from complete defoliation. These roses are hardly care-free.

Adrian Higgins: I have grown Knock Out for 10 years in a location that is not optimal, but black spot is not a problem. I have seen black spot on really stressed Knock Out roses (pot bound and neglected in a nursery), otherwise the plant has been black spot free (95-99 percent) in my experience.

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Wash. DC Help: I would love to have roses all year round. In my house I mean. Is there a mini rose bush or plant that I can have inside that looks just as pretty and smells just as good on a smaller scale in my home. I would love to have a pot on every table so when you walk by you can smell the goodness. Help if you can.

Adrian Higgins: Roses won't be happy indoors. Too dark and too warm. They are grown year round in greenhouses, but with intensive help and in highly controlled environments.

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Anonymous: I just want to say that there are finally some products out there that really do get eliminate mosquitoes.

One of my neighbors got one; I believe it works like a magnet, and I think it's called Defender. But it works for up to an acre and so far I have fewer mosquito bites this year than I would get in 5 minutes last year. It's really changed my life. I can spend so much more time in the garden than I ever have. In fact, that's where I am right now.

So I recommend people either get one of these, or get a great neighbor like I have.

Adrian Higgins: Thanks for the tip. I will say it's still early in the mosquito season. I use an organic cream on my skin, which works pretty well.

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Cilantro: I'm into herbs and have several. All are doing great except my cilantro. It is getting stringy and the leaves are not tasting as yummy and it is not growing well. It is right between some sage and parsley both of which are thriving. Any advice on what could be causing bad cilantro this year?

Adrian Higgins: Cilantro is a cool season herb. Grow indoors from seed in January, set out in March and enjoy until Memorial Day. Repeat the cycle beginning in late July for a fall harvest.

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Growing peas: Hi Adrian! I'm a first-time pea grower, and I have three pea plants growing in a pot (climbing a tomato cage for support). They're not very tall, but this morning I noticed a couple of very small pods forming on them. But I also noticed that the lower leaves on all three plants are turning yellow and starting to wilt. I guess this is a dumb question, but does that mean they're dying? Is there anything I can or need to do about this?

Adrian Higgins: I think this will have to be the last, sorry. Garden or English peas are hit or miss in our climate, the key is to get them going early so they mature before the heat sets in. This spring was a near bust in getting in early crops, due to the snow in February and frozen ground in March. Sugar and Snap peas are more heat tolerant and will work much better. I have become a convert, seeing them as part of the blog I do with Cindy Brown for the Post's Food section (All We Can Eat - Groundwork). Thanks so much for your comments, which help me in sharing the word about the beauty of gardening.

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