How to choose and grow roses
The rose is the queen of flowers, the most loved and widely planted shrub in all temperate parts of the world. More than 14,000 varieties are grown. Although mostly deciduous, roses can be evergreen in mild climates. Their stems, sometimes quite prickly, may be erect, arching, trailing, or scrambling. Leaves are divided into three, five, or seven leaflets, usually with toothed margins.How to choose and grow roses
Roses are prized for their lovely, often scented flowers. Many types carry their blossoms in clusters, but some (notably hybrid teas) tend to bear their flowers singly, one bud per stem. Some blooms are flattish rosettes; others are cupped; hybrid tea roses have a conical shape, with high, pointed centers. The blossoms range from single (4 to 8 petals) to semidouble (9 to 16 petals), double (17 to 25 petals), full (26 to 40 petals), and very full (to 150 petals or more). Thanks to the hybridizing efforts of breeders and enthusiastic gardeners over many centuries, roses are now available in all colors except blue and black. Many are blends—different shades of a single color or more than one color.
Rose bushes are natural choices for flower beds and shrub borders; some also make fine hedges or container plants. The largest are the old garden roses, grandifloras, and shrub roses. Hybrid teas and floribundas generally grow with more restraint. Miniature roses are the smallest; some reach only 1 ft. tall. For a little formality, consider a standard rose, a bush rose grown on a tall, bare stem; a patio rose is a small standard.
Groundcover roses make a low, mounding carpet of color up to 8 ft. wide. They are most often massed on a slope or an area of the garden where other knee-high shrubs might be used. They also make good container plants.
Climbing roses grow on vertical surfaces or freestanding supports. The most vigorous ones will cover a house roof or grow to the top of a large tree. More moderate climbers clothe arbors and tall walls. Small climbers, sometimes called pillar roses, are suitable for a pyramid or trellis. In addition to the roses that are classified as climbers, there are old garden roses and shrub roses that climb, as well as climbing miniature roses.
The most reliable way to find roses that grow well in your climate is to visit municipal or private rose gardens in your region. Varieties that are performing well there are obviously good choices—and you’ll see how big they grow. Climate affects the size of many roses; for example, ‘Sally Holmes’ in Seattle might be a 5-ft.-tall bush, but in Southern California it can be a huge rambler, with canes to 35 ft. long. David Austin roses grow with admirable reserve in England and similarly cool climates in the West, but in the warmest zones, they can grow much taller.
In mild-winter regions, some roses adapted to very cold climates produce few flowers. In areas with cool summers, roses with a large number of petals tend to “ball,” opening poorly or not at all. In the absence of heat, dark-colored flowers may appear muddy rather than vibrant. Also, because the overcast skies and fog common in cool-summer zones encourage foliar diseases such as mildew, rust, and black spot, varieties noted for their disease resistance grow and bloom better there.
In hot-summer areas, flowers open rapidly. Varieties with few petals (under 30) may go from bud to fully open blossom in just a few hours on a hot day. Those with more petals take longer to open and stay attractive longer. Some colors (the golden yellow in ‘Peace’, for example) may fade almost to white in very hot weather, and dark reds may sunburn. During intensely hot weather, plants may however, almost go dormant, causing flower production to drop markedly. (To avoid these problems, plant roses where they will receive afternoon shade, and away from reflected heat from light-colored surfaces.) Best flowering in hot-summer areas is in spring and fall.
If you live in a cold-winter area, choose roses that are sufficiently cold hardy for your region, or protect less hardy varieties in winter . In Zones 1–3, hybrid teas, grandifloras, and floribundas need protection. However, the hardy hybrids (bred primarily in Canada and Iowa) can go through winter with little or no special protection. Many old roses (chiefly those that flower only in spring), as well as a number of species roses and their hybrids, also survive in Zones 1–3 with scant or no winter protection. In Alaska, the native Nootka rose is hardy enough to need no protection, as are some of the other extra-hardy species roses and their hybrids, such as the wonderfully fragrant rugosas (R. rugosa).
As you research your selections, you can check the American Rose Society (ARS) rose ratings, available in the ARS’s Handbook for Selecting Roses, sent free to members. (See www.ars.org for more information.) The ratings are numeric assessments of each rose from 1 to 10 based on a national average of scores for that plant. The higher the number, the better the rose. But a rating does not tell the entire story: a rose with a low rating may fail in some regions but flourish in others.
Mail-order catalogs and/or Web sites offer the widest choice of roses; they are practically the only way to shop if you are looking for lesser-known varieties. You’ll also find roses for sale in local nurseries and garden centers, home improvement and hardware stores, and even some supermarkets.
Container-grown roses. Plants in plastic or pressed-peat pots are available from retail stores from early spring through fall, year-round in mild-climate regions. The best time to shop is in mid- to late spring, when the plants are in bloom, the largest selection is available, and you have a chance to plant out your purchases before summer heat arrives. You can, however, plant container-grown roses at any time during the growing season (see “Planting”).
Choose plants with strong new growth and healthy-looking leaves. A large (preferably 5-gal.) container is better than a small one; it’s less likely that the roots had to be cut back severely to fit in the container when the plant was potted. Avoid plants with roots protruding from the bottom of the container, as well as those showing weak growth or blackened areas of dieback on the canes. These are all signs that the plant has been in the container too long and may not establish well in your garden.
Bare-root roses. During late winter and early spring, nurseries and stores may also offer bare-root roses; these are dormant plants with no soil on the roots. If you shop from mail-order nurseries, typically you’ll receive bare-root plants, and the shipping may begin in fall. It doesn’t harm the roses to be dug up and transported bare root, and although you can’t see your roses in flower, bare-root plants have advantages over plants sold in containers: they are generally less expensive, and they may establish vigorous roots faster.
Bare-root plants are graded 1, 1 1/2, or 2, number 1 being the best. Suppliers usually offer only grade 1 plants, and they will often replace plants that fail to grow. A healthy bare-root rose has thick, green canes and a big cluster of sturdy, fibrous roots. Reject any with dried-out or squishy roots or with canes that are weak, shriveled, or beginning to leaf out.
Be cautious about buying packaged bare-root roses that are displayed indoors on retail store shelves; the roots are wrapped in a moist material, but the indoor heating may cause the material to dry out. Buy these roses as soon as they appear for sale, rather than when they are marked down as bargains. In milder winter zones, you can plant bareroot roses throughout winter. In areas where the ground freezes, plant either in fall before the soil freezes (then protect plants over winter) or in early spring after the soil has thawed.
Budded or own-root roses. Many old roses, species roses and their hybrids, and virtually all miniature roses are propagated by cuttings and grown on their own roots. Most modern roses are budded onto a standard understock, a completely different rose variety whose root system thrives in a wide range of soils and climates. There is a current trend, however, to try new varieties on their own roots and grow them that way when successful.
Both budded and own-root roses grow well and produce fine flowers. Budded plants are often larger at the time of purchase than own-root plants, but both kinds will be equally husky within a year or two. Own-root roses do have one advantage: if the plant is killed to the ground by cold (or mowed down by accident), it will regrow from the roots as the rose you want. Regrowth from roots of a budded plant, in contrast, will be from the understock rose.
CHOOSING A PLANTING SITE
Choose a planting place where your rose will receive at least 6 hours of sunshine daily. If your weather is consistently cool or overcast, choose a location that’s open all day to any sun that might appear. If summer heat is intense, find a spot that receives filtered sunlight during the hottest afternoon hours.
Soil for roses should drain reasonably well; if the soil in your chosen spot does not, the best alternative is to plant in raised beds. Don’t locate roses too close to trees or large shrubs; their roots will steal the water and nutrients intended for your roses. Choose a spot where there is good air circulation, but avoid windy locations. High winds can wreck the flowers and increase transpiration from the leaves, making frequent watering necessary.
In preparation for planting, the first step is to decide on the spacing between plants. Generous spacing between plants aids air circulation, which reduces the incidence of mildew, black spot, and other foliage diseases. Exactly how far apart to plant depends on the growth habit of the roses and on your climate. The colder the winter and the shorter the growing season, the smaller the bushes will be; where the growing season is long and winters are mild, bushes can attain greater size. But some varieties are naturally small, others tall and massive—and those relative size differences will hold in any climate. In the coldest zones, you might plant the most vigorous roses 3 ft. apart; in milder climates, space vigorous sorts 6 or even 8 ft. apart.
The next step is to prepare the soil. Dig it deeply, incorporating organic matter such as ground bark, peat moss, or compost to help aerate dense clay soils and improve moisture retention in sandy soils. Add a complete fertilizer to the soil and dig supplemental phosphorus and potassium into the planting holes. If you are planting new roses in a spot where existing bushes have been growing for 5 or more years, be sure to add plenty of rich organic material, as the soil is most likely quite spent.
Healthy, ready-to-plant bareroot roses should have plump, fresh-looking canes and roots. Before planting, immerse the entire plant in water for up to 2 days to be certain all canes and roots are plumped up. After planting, some gardeners mound mulch over the bud union (the knob from which the canes grow) and around the canes to conserve moisture, then gradually (and carefully) remove the mulch when the leaves begin to expand.
If you are planting a budded plant (whether container grown or bare root), set the plant in the hole so that the bud union is just above soil level. In Zones A1–A3 and 1–3, some gardeners set the bud union 1–2 in. beneath the soil surface for increased protection from cold, but since this usually results in the production of fewer canes, many gardeners in these cold-winter zones keep to the standard guideline (bud union just above soil level) and give their roses plenty of winter protection.
WATERING AND MULCHING
With the exception of some old garden roses and species roses that thrive on little water once they are established, roses need watering at all times during the growing season. Inadequate water slows or halts growth and bloom.
Water deeply enough to moisten the entire root system (16–18 in. deep). How often you need to water depends on soil type and weather. Big, well-established plants need more water than newly set plants, but you will need to water new plants more frequently until they are established.
Various irrigation options are available. Basin flooding is a simple way to water individual rose plants. If you have a drip irrigation system, you will be able to water many plants at one time. Overhead sprinkling freshens foliage and helps remove dust; it can also wash away aphids, spider mites, and the spores of powdery mildew and other fungal leaf diseases. On the other hand, overhead sprinkling washes off sprays that were applied to control pests and diseases, and it may leave mineral deposits on foliage if water is hard. If you use an overhead sprinkler, do it early in the day to allow foliage time to dry off during daylight hours; leaves that stay wet for several hours are more likely to develop powdery mildew and other foliage diseases. Even if you irrigate in basins, give plants an occasional morning shower to clean dust off the foliage (if rains don’t do it for you).
Each spring, spread a 2–3-in.-thick layer of fresh mulch around your roses. Mulching conserves moisture and deters weed growth. It also helps keep soil cool—a benefit in all but the coolest-summer climates.
Though roses have a reputation for being heavy feeders, their nutrient needs vary depending on rose type and your soil’s natural fertility. Many old roses, shrub roses, and species roses do not need regular fertilizer if growth is satisfactory. But for many repeat-flowering modern roses, regular fertilizing is needed to produce the most gratifying results.
In the mildest-winter climates (Zones 8, 9, 12–24; H1, H2), give established roses their initial feeding with a complete fertilizer in February; elsewhere, give the first feeding just as growth begins. Thereafter, time fertilizer applications to bloom periods. For roses that flower repeatedly throughout the growing season, fertilize after each blooming cycle has ended, when new growth is just beginning. For roses that bloom only in spring, one additional feeding just after flowering ends will encourage vigorous new growth and plenty of blooms next year.
Where winters are cold, stop feeding in late summer or fall, at least 6 weeks before the first expected hard frost. In mild-winter zones experiencing virtually no subfreezing weather, you may continue fertilizing until mid-October for a crop of late-fall flowers.
Dry fertilizer, applied to the soil, is most frequently used. A variation on this type is controlled-release fertilizer; follow directions on the package for the amount and frequency of applications. Liquid fertilizers are useful in smaller gardens using basin watering. Most liquid types can also be sprayed on rose leaves, which absorb some nutrients immediately. If you are looking for an organic fertilizer for roses, try dehydrated alfalfa; it smells better than fish emulsion.
CONTROLLING PESTS AND DISEASES
Although some roses are especially susceptible to pests and diseases, most of these plants thrive with just a little preventive care. Well-tended, healthy roses are less likely to fall prey to pest infestations or diseases. To reduce the risk of trouble, choose roses that are suitable for your climate and are notably disease resistant (breeders have come a long way in producing roses that resist black spot, powdery mildew, and rust); prepare the soil well; feed and water diligently (being careful about the timing of overhead watering); and prune to ensure good air circulation around the leaves.
Start each year with a garden cleanup, removing prunings, leaves, and old mulch, which may harbor overwintering insect eggs and disease spores. Then, if you have reason to think you need it, spray the plants and the soil to kill any remaining insect eggs and disease spores. Do this before the plants leaf out, and use a natural product such as dormant-season horticultural oil or lime sulfur.
Allies in the battle against rose pests include ladybugs, lacewings, beetles, flies, spiders, birds, and wasps. You can buy predators such as ladybugs at nurseries and release them in your garden; encourage them to stay awhile by setting out plants that attract them, such as dill, fennel, and yarrow. Avoid using broad- spectrum pesticides, which kill beneficial insects along with pests.
Watchfulness is an excellent strategy for maintaining healthy roses. A very effective way to keep pests from building up large, damaging populations is to pick off the early visitors and drop them in a bucket of soapy water. Or blast the tiny ones from your roses with a jet of water.
Rose midges are a problem in coastal Northern California and the coastal Northwest. The almost microscopic adults lay eggs in the growing tips of rose stems; when the larvae hatch, they bore into the developing rose buds, deforming the buds and leaving blackened, withered tips. The larvae then fall to the ground and pupate, perpetuating the cycle. Snip off and bag any affected shoots as soon as you notice them, and clear and dispose of all leaf litter, weeds, and debris. Try laying black plastic under the plants so the larvae cannot pupate. Lose no time contacting a good local nursery for advice on the best treatments if the damage continues; repeated soil drenches or foliar applications of systemic insecticides may be the only viable options.
Rose slugs—insect larvae that chomp and tatter rose leaves—have been a huge problem in recent years in coastal California. The most effective treatment is Spinosad, a pesticide derived from a soil bacterium. It does not harm most beneficial insects.
Powdery mildew, rust, and black spot are the most likely diseases to appear on your roses at some point. At the first sign of disease, remove affected leaves and debris. Don’t wait until the damage is substantial before you spray during the past season.
Black spot is most troublesome in warm summer weather when there is humidity or rainfall to sustain and spread it. For a nontoxic control, apply a spray made from 2 tsp. of baking soda and 2 tsp. of fine-grade horticultural oil dissolved in 1 gal. of water. In years with wet springs, anticipate downy mildew; some gardeners spray a fungicide preventively in a wet spring to prevent defoliation.
For local help with pests and diseases, consider joining the American Rose Society (www.ars.org). Its consulting rosarians advise member gardeners on rose problems at no cost.
PROVIDING WINTER PROTECTION
Where winter temperatures regularly drop to 10°F/–12°C or lower, roses that are somewhat tender, such as many hybrid teas, floribundas, and grandifloras, need protection against cold. Low temperatures can kill exposed canes; repeated freezing and thawing will kill canes by rupturing their cells; and winter winds can desiccate exposed canes.
A healthy plant that is hardened off before the first hard frost withstands harsh winters better than a weak or actively growing one. Prepare plants for winter by timing your last fertilizer application of the growing season so that bushes will have stopped putting on new growth by the expected date of the first sharp frost. Leave the last crop of blooms on your plants to form hips (fruits), which will aid the ripening process by stopping growth. Keep plants well watered until the soil freezes.
After a couple of hard freezes have occurred and nighttime temperatures remain consistently below freezing,mound soil over the base of each bush to a height of 1 ft. Collect the soil from another part of the garden; do not scoop soil from around the roses, exposing their surface roots. Cut excessively long canes back to 2–4 ft. (the lower figure applies in Zones A1– A3 and 1, 2, and 3a). Then use soft twine to tie the canes together and keep them from whipping around in the wind.
When the mound has frozen, cover it with evergreen boughs, straw, or other fairly lightweight material that will act as insulation and keep the mound frozen. A 3–4-ft.-high wire-mesh cylinder filled with noncompacting insulating material (such as straw, hay, oak leaves, or pine needles) may preserve much of the cane growth it encloses.
Remove the protection in spring after frost danger is past. Gradually remove the soil mounds as they thaw, working carefully to avoid breaking new growth that may have begun sprouting under the soil.
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