Gardening Advice: Rose Problems and Solutions

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Even if you choose a spray that is clearly labeled for the culprit or disease, if you don’t follow the label directions regarding timing and amount (not to mention safe application), it won’t be as effective as you want it to be.
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“The Anxious Gardener’s Book of Answers” by Teri Dunn Chace identifies the 100 most common gardening mistakes and gives you the information you need so that you’ll never make them. Or, if you’ve already goofed, it tells you how to fix the mistake.

Your garden is supposed to be fun — a place to relax in and recharge your batteries, a source of beauty and pleasure. But all too often, things go wrong. Those expensive tulip bulbs you planted last fall never came up. Your lilac doesn’t bloom. The lawn looks terrible. And worst of all, you don’t know what to do about it. The Anxious Gardener’s Book of Answers (Timber Press, 2012) contains great gardening advice to help you solve virtually any gardening challenge. In this excerpt from the chapter “Roses,” author Terri Dunn Chace provides solutions to your most pressing rose problems.

Desperately spraying roses

Roses, particularly the older yet still popular hybrid teas, do get pests and diseases. When you find your bush infested with aphids or Japanese beetles, or mildewed, or marred by blackspot, it’s only natural to be upset. You may storm down to the garden center, scoop up a can of a product whose label mentions treating rose problems, and blanket the bush with spray. But unless you have the right product, it won’t help–and could even be harmful. Even if you choose a spray that is clearly labeled for the culprit or disease, if you don’t follow the label directions regarding timing and amount (not to mention safe application), it won’t be as effective as you want it to be.

The right way to do it: Take a more methodical approach. First, examine the plant carefully, including under the leaves, to accurately diagnose the problem and assess its scope. Next, pick off all afflicted plant parts, as well as any on the ground at its base, and throw them in the trash.

Then research remedies. Japanese beetles can be handpicked and drowned in a bucket of soapy water (do this in the evening, when they congregate). You can blast off aphids with a spray from the hose. Common rose diseases respond to correctly applied sprays, but also to careful sanitation and proper care (including watering on the ground so the leaves don’t get splashed). If you decide to spray, try less-toxic treatments first and always read and heed the label. If the material is at all dangerous–this sort of caution will be noted on the label–protect yourself with eyewear, gloves, long pants, and long sleeves.

If I goofed, can I fix it? With renewed attention and prudent care, a rose will often recover from a common pest or malady; if it doesn’t, it’s time to replace it, possibly with a tougher, more resistant variety. Let this be a reminder to take good care of your rose plants so they are less vulnerable to problems. Desperate spraying is not only foolish and wasteful, it doesn’t remedy the actual problem.

Choosing a disease-prone rose variety

Let’s be honest: we love, and grow, roses primarily for their gorgeous flowers. It’s all too easy to choose one based on the beauty of its blossoms. Once in the ground and growing for a while, the plant indeed produces the blooms you were dreaming of. But soon you begin to see its flaws, mostly in the growth or the leaves, but possibly in buds and blooms, too. Your plant has blackspot (worst in hot, humid weather) or suffers from mildew (which thrives in dry conditions). Or it may even have an incurable rose virus, such as Rose Mosaic Virus (RMV; deformed new growth, yellow mottling on leaves) or Rose Rosette Disease (RRD; distorted, crinkled leaves, dark reddish-purple color all year, rapid aberrant growth and elongation). If caught early, you may be able to fight the common diseases. There is no remedy for the viruses except ripping out and disposing of the afflicted plants.

The right way to do it: Check with a local rose expert before you buy or plant a rose, and tell her you want one resistant to rose diseases prevalent in your area. Or get assistance at your nursery from someone who knows roses (reputable nurseries will sell only virus-free stock). For all the susceptible roses, there are plenty of worthy and gorgeous tough ones whose foliage creates a handsome foil for those beautiful blooms.

If I goofed, can I fix it? Legions of rose lovers have put up with common rose diseases by picking off and getting rid of affected leaves and plant parts or spraying–they love the flowers too much to forgo them. If you are among the smitten, undertake prevention and control wisely. Diagnose the disease correctly, then research the remedies, which can vary from spraying with baking-soda solution to using a fungicide or other chemical control. Get good advice on what to do, and when, from your local consulting rosarian (see the American Rose Society) or rose club.

Remember, too, that practicing good sanitation (get rid of afflicted plant parts), judicious pruning (to improve air circulation in and near the plant), and watering on the ground (rather than splashing the leaves) can help.

Pruning roses the wrong way

When a rose outgrows its space, sending its thorny canes taller or wider than you want them to go, you’ll want to prune. Or perhaps you wish to shape an unruly rose to achieve a tidy, formal look. Either way, it’s important to prune at the right time and in the right way. While it’s often tempting to clip and shape a rosebush in the fall as the leaves drop and the profile of the plant is more obvious, this is the worst time in colder climates. Cold and freezing air can damage the fresh cuts (causing blackening and dieback) and stunt or kill the fresh flush of new growth that cutting often inspires.

Improperly executed cuts can also mar the look of a rose plant. Cuts made too close to a bud cause it to shrivel up and die. Cuts made over an inward-facing bud encourage growth in the wrong direction, contributing to a crowded, tangled bush. Overzealously cutting long-stemmed bouquets of blooming roses in the summer can scalp a plant.

The right way to do it: Generally speaking, the best time to prune most roses is in early spring, just as the buds are beginning to swell and after all chance of hard frost is past. (In warmer climates, where freezing is not an issue, you may safely prune in fall or winter.) Start by taking out winter-damaged and very old canes at the ground. If the plant is grafted, closely cut off unwelcome suckers emanating from below the graft. Next, remove branches that are rubbing, crossed, or too close together. Shorten trailing stems. Aim for a half-dozen or so healthy canes, shortening them to about a foot high. As spring arrives, the revitalized plant will surge into fresh new growth.

A proper cut is made with a sharp, clean pair of pruners or loppers, on a slant, about 1/4 inch above an outward-facing bud. If a branch has leafed out, cut just above a five-leaflet side stem.

If I goofed, can I fix it? Give an improperly pruned rose a year off, during which time it will hopefully generate some new growth and recover, even if it doesn’t look great. Then prune early the following spring as described.

Planting roses the wrong way

A rose planted in poor-quality or poorly drained soil, or in a spot with not enough sunshine, sulks. It may not die, but it will never produce lush, healthy foliage or lots of pretty blossoms, and its growth may be stunted or look lanky. A rose planted too deeply struggles because its root system is not getting sufficient water and oxygen, and it can suffocate. One planted too shallowly, however, has a root system that is too exposed.

The situation is further complicated if you are planting a grafted rose. Set the plant in too shallowly, and it may produce unwanted canes off the rootstock rather than the desirable grafted plant.

The right way to do it: Whether you are planting a bareroot rose or a potted one, set it in the ground at the same depth at which it was growing–there will be a line evident on the main stem. Fine-tune this directive if it is a grafted plant. In mild areas, position the graft union slightly above the soil surface; in colder climates, bury it slightly below the soil surface.

Plant a rose in a sunny, prepared site in good, organically rich soil that drains well. For a bareroot one, create a cone of soil in the hole and gently array the roots over it. For a potted rose, take time to gently tease the roots loose so they can grow into the surrounding soil. To avoid air pockets, backfill the hole about halfway, then water well and let it soak in before continuing. Make adjustments as needed at the end of the job, adding or removing soil until the plant is at the desired depth.

If I goofed, can I fix it? Assuming the rose is not on its last legs after you realize you planted it incorrectly, dig it out. Temporarily move the plant into a large pot or protect the root system from drying out by laying a damp cloth over it while you prepare a new hole, in a better spot if necessary. Replant as described.

Letting a rose produce suckers

Something is obviously wrong when, one or two seasons into life in your yard, a rose you chose for its beauty starts putting out wayward stems with thin, small, or unattractive leaves, shooting up suckers from the base, and producing flowers that are not what you expected. You’re so disappointed and disgusted, you’re ready to tear it out.

Were you sold a mislabeled plant? Maybe. But more likely you didn’t protect the graft, and winter’s cold, or something else–a wayward string trimmer?–knocked off or killed the grafted or top plant. What you are seeing is growth produced by the rootstock. Rose rootstocks are not chosen for their beauty, but for the cold-hardiness, uniformity, and even disease-resistance they can confer to the more attractive plant grafted on top.

The right way to do it: Gardeners who grow roses in colder climates have two choices. If you want to enjoy a rose that is grafted atop a rootstock (if you are not sure if the one you are contemplating is grafted, ask or look for the telltale bulge in the stem just above the roots), plant it correctly. Set it so the graft, or bulge, is slightly below the soil level, and mulch several inches deep over the plant to help it through the winter months.

Alternatively, shop for an own-root rose. Many shrub roses are in this category, including lovely heirloom varieties. Make sure it is rated hardy in your climate zone. If winter kills or harms the top, when the roots send up new growth, it will be the same plant you expected and wanted.

If I goofed, can I fix it? If you planted a grafted rose too shallowly and winter (or a mishap) killed the top, there is no recourse. Tear out the remains, including all of the unwanted rootstock, and start over. Invest in a cold-hardy own-root rose, or plant a grafted rose properly and be sure to mulch it well come winter.

This excerpt has been reprinted with permission from The Anxious Gardener’s Book of Answers, published by Timber Press, 2012.