Roses (Rosa spp.)
Fundamental Facts
HARDINESS: Zones 4 to 9
PREFERRED SOIL pH: Near neutral
PREFERRED SOIL TYPE: Fertile, loamy
PREFERRED LIGHT: Sun
ATTRIBUTES: Beautiful, fragrant flowers; for specimens, beds, groundcovers, hedges
SEASON OF INTEREST: Late spring to fall
FAVORITES: Landscape, English, rugosa, Horibunda, and hybrid tea roses
QUIRKS: Plants will rebloom if deadheaded and fertilized after each flowering
GOOD NEIGHBORS: Allium, biuebeard, candytuft, catmint, lavender, petunia, sweet alyssum
WHERE IT GROWS BEST: Sunny, well-drained sites with moderate winters
POTENTIAL PROBLEMS: Blackspot, powdery mildew; Japanese beetles
PRUNING Lives for decades; prune in late winter to remove dead wood
CRITTER RESISTANCE: Fair; vulnerable to deer and rabbits
SOURCE: Nursery plants
DIMENSIONS: 3-6 ft (1-1.8 m) tall, 2-5 ft (0.6-1.5 m) wide
Rose in the Landscape
Roses have been cherished as garden plants for centuries. Although modern roses are more tolerant of disease than their ancestors are, these beauties remain somewhat demanding. However, with careful attention to plant selection, planting site, pruning, and fertilization, anyone can grow at least a few roses without having to constantly ward off problems.
Roses are often grown in rose beds, so that their growing requirements can be easily met, or they may
be mixed with a few annuals or low-growing perennials. Many roses, however, can be grown in a perennial border, where they blend magnificently with bluebeard, catmint, and lavender. Other types can be massed as groundcovers, grown as hedges, or showcased as specimens. Small roses can even be grown in containers.
The Language of Roses
Roses are divided into a number of types based on their ancestry, growth habits, flower form, and uses in the landscape. And although some types are easily identified, such as the long-stemmed roses known as hybrid teas, modern "landscape" roses are difficult to categorize. Any gardener who has fallen in love with roses will eventually acquire a specialized vocabulary to better understand these intriguing plants, but most gardeners can get by with a few terms.
Landscape rose is a broad category used to identify roses developed within the last 15 years or so that are disease resistant and usually require only casual pruning. Varieties such as 'Simplicity', 'Flower Carpet', and 'Carefree Wonder' are in this category. Landscape roses often have little fragrance and their flowers tend to be small, but the plants can be counted on to bloom over a very long season.
English rose describes a large group of roses that combine the fragrance and flower form of old roses with the disease tolerance of modern types. These are typically vigorous, bushy plants that bloom heavily in late spring and lightly in summer or fall, provided they are pruned and fertilized between flower flushes. When disease problems arise on English roses, such as 'Heritage', prompt removal of the affected leaves can usually preserve the plants' health.
Rugosa roses are a species with tough, quilted leaves that is naturally resistant to insects, disease, and even salt spray. Rugosas have been used to breed varieties that tolerate both disease and extreme cold. In cold climates, the most dependable roses are rugosa varieties such as the white 'Blanc Double de Coubert' and deep pink 'Hansa'. If old flowers are not pruned off, rugosa roses produce colorful hips that are rich in vitamin C, providing food for birds in winter.
Floribunda roses load up with large clusters of flowers in late spring, with sporadic blooming thereafter. Fragrant and beautiful, floribundas, such as the white 'Iceberg* and red 'Europeana', are the best roses for planting along a fence, although problems with fungal leaf diseases such as blackspot or powdery mildew often follow prolonged damp spells.
Hybrid tea roses are prone to every rose malady, but gardeners forgive these flaws because of the beauty and fragrance of the flowers. Cultivars number in the thousands and include the revered red-flowered 'Mr. Lincoln' and coral red 'Fragrant Cloud'. If you cannot resist dabbling in these temperamental beauties, consult a rose society or display garden in your area to learn which varieties grow especially well under local conditions.
Growing Roses
Select a sunny site where you will have easy access to care for the plants. You can set out dormant bare-root roses, which are usually offered by mail-order nurseries, in early spring, before the first leaves appear. Later in the season, after the plants have begun active growth, plant only container-grown roses. These can be planted all summer, providing the soil around their roots is kept moist afterward. Roses begin developing new roots at the same time that they grow new leaves, so early planting gives them an entire season to become established.
To prepare for planting, dig a hole 18 in (45.7 cm) deep and wide and enrich the soil with compost, well-rotted manure, or peat moss. Mix in a timed-release fertilizer or a commercial plant food developed for roses according to package directions.
Next, look at the main stem. Many roses are grafted, which means the stems of a desired variety have been attached to the roots of a hardier rose. This forms a call used bump just above the roots, which is called the graft union. It can be injured by cold, so in Zones 4 to 6 this bulge should be 1-4 in (2.5-10.2 cm) below the soil line; the colder the winter, the deeper it should be. Where winters are mild, set plants higher, with the graft union about 1 in (2.5 cm) above the soil.
If you are planting a container-grown rose, adjust the depth of the hole with soil so that the graft union
will be at the desired level. Slide the plant gently from the pot, set it in the hole, and fill around it with soil. If you are planting a bare-root rose, create a cone-shaped mound of soil in the center of the hole at the height required for the graft union to be at the desired level. Set the plant atop the mound and spread the roots out around the cone's sides. Fill the hole around the cone carefully with soil.
Water the plants in well and spread 2-3 in (5.1-7.6 cm) of compost or other organic mulch. If there is no rain, water every third day with a deep, slow soaking, taking care not to wet the foliage. Once roses are established, they need 1 in (2.5 cm) of water weekly. Fertilize established roses at least twice each season, in spring and early summer, with a balanced timed-release fertilizer or one formulated for roses. In Zones 7 to 9, where hybrid tea roses often rebloom heavily in the fall, feed them a third time in late summer.
Prune roses in early spring to remove dead stems and thin out the canes, which improves air circulation and discourages fungal infections. To help plants rebloom, prune off old flowers as they fade, cutting just above a leaf that has 5 leaflets.
From Zone 6 northward, insulate the base of plants from extreme cold by piling a 12 in (30.5 cm) deep cone of soil and mulch around plants in late fall, after they go dormant. Even if buds higher up on the plants are killed, those protected beneath the mulch will survive and form the first branches on the next season's plants.
The Trouble with Roses
The list of every problem a rose might have would be long indeed, but the three most common ones are black-spot, powdery mildew, and Japanese beetles. Blackspot is a fungal disease and the primary problem that weakens roses. In arid climates blackspot is uncommon, but wherever nights are humid you can expect to see black spots appear on the leaves, which eventually wither and fall. Healthy plants with good natural resistance will survive small outbreaks, but highly susceptible plants need to be sprayed with a commercial rose fungicide as directed on the label.
A rose fungicide usually treats or prevents powdery mildew as well. This fungal disease causes gray or white patches to develop on leaves in a wide range of climates, usually in late summer when days are warm and humid and nights are cool. Roses are usually more resistant to this disease than to blackspot.
Several types of beetles eat rose leaves, but iridescent green Japanese beetles, prevalent in the eastern part of the continent, make short work of whole plants, blossoms and all. Hand-pick and dispose of beetles early in the morning when they are sluggish, or spray plants regularly with the botanical insecticide neem as directed on the package. Rose leaves and flowers are also a treat for browsing deer and rabbits. The best critter defense is a fence, but you can tuck bars of deodorant-formula bar soap among plants or apply a commercial repellent as directed on the label. Or switch to trouble-free rugosa roses, which are more resistant to all these problems.