Rosemary has many culinary and ornamental uses. In the lower South, it is a handsome evergreen shrub. Rub its leaves and a pine fragrance fills the air. Rosemary's unique aroma and flavor accent a variety of foods and crafts.
In the Landscape
A slow-growing, upright, bushy herb, rosemary often reaches 3 to 5 feet tall after several years of growth. The stems become woody with age and are covered with green needlelike foliage. Prostrate or creeping selections range from tiny small-leafed plants suitable for bonsai to large-leafed plants usable as a ground cover on a dry hillside. These rarely grow taller than 1 to 2 feet, with short, narrow leaves. They make excellent container plants, topiaries, or edgings for rock walls and terraces in the warmer areas of the lower South.
Rosemary flowers vary from white to pink to blue, and the blooming time depends on the selection. Plants that bloom in late spring or early summer attract bees; those that bloom in November and December are a delight during the winter holidays. Use rosemary as an evergreen hedge in Zone 8 and south. Farther north, grow rosemary in a container and bring it indoors to overwinter.
Planting and Care
This evergreen perennial thrives without winter protection in Zone 8 and farther south. In Zones 6 and 7, it may be damaged by severe freezes. Heavy mulching helps rosemary survive through winter, as does planting it beside a south-facing masonry wall. The wall will absorb the sun's warmth and radiate heat at night, as well as shield the plant from north winds. If you live in a windy location, always choose a protected spot for your rosemary, because extreme cold in Zones 8 and 9 can kill the tops of this herb. Keep a rosemary plant in a container year-round in case plants in the ground are lost during a hard winter. However, beware that if the soil in the pot dries out and the plant wilts, rosemary does not recover.
Rosemary likes full sun but will tolerate partial shade. The best way to start rosemary is from transplants. Set plants out in spring as soon as the soil warms or in early fall. Rosemary needs light soil with a pH of 6.0 to 6.7; add lime, if necessary. Rosemary is suited to raised beds or containers as it requires good drainage. Mix a slow-release fertilizer with the soil before or during planting, and fertilize again the following spring.
Layering is an almost foolproof method of obtaining new plants once you have a planting started. You can also start new plants from stem cuttings in spring and summer. Starting from seed is not practical; seeds are slow to germinate, and the rate of germination is poor. It takes three years to produce a good-sized plant from seed, and seeds do not produce a predictable, dependable clone.
Rosemary likes evenly moist soil but is susceptible to root rot if kept too wet. Let the soil surface dry out between waterings. Mulch to keep roots moist in summer and protected in winter, but do not allow the mulch to touch the crown of the plant. Prune dead wood in the spring.
If you live in an area north of Zone 8, move rosemary to a protected location or bring it indoors for winter. Place in a cool spot, about 45 degrees, with bright sunlight. Water infrequently?just enough to keep the soil moist.
Species and Selections
Many selections of rosemary are available. These vary in form, flavor, flower color, and winter hardiness. Check with local sources for recommendations of selections that perform well in your area. Arp and Old Salem are upright selections considered to be among the hardiest. Prostrate types are generally less cold hardy and should be grown in containers or hanging baskets that can be moved to a protected location. While most types have pale lavender flowers, some selections of rosemary, such as Benenden Blue, Santa Barbara, Collingwood Ingram, and Tuscan Blue, have blue blooms that are quite showy. Try Albus for white blooms or Majorca Pink or Corsicus for pink.
Harvest, Storage, and Use
For fresh use, cut stems anytime. To dry the leaves, harvest just before the plant blooms. The flavor will be stronger, and it is the best time to prune plants. Dry stems on a rack, or bunch several sprigs and hang them to dry. Then strip the leaves from the stem. Rosemary sprigs also can be frozen or stored in vinegars and refrigerated oils.
Rosemary's strong flavor combines well with other herbs, but use its leaves sparingly. Strip fresh leaves from stems, chop, and add as an accent in soups, meats, stews, or vegetables. Work rosemary into bread dough, or mix it with wine or olive oil and garlic for a marinade.
Rosemary can become a simple luxury when you drop a sprig into bathwater, add it to a bouquet, or wrap it around a napkin ring. Fresh rosemary works well in wreaths. Use dried rosemary in sachets. Burn a bunch of rosemary branches over charcoal when grilling to enhance the flavor of foods.
Rosemary is susceptible to powdery mildew and root rot, especially along the Gulf Coast. As a preventive measure, provide excellent drainage and good air circulation. Always clean the garden thoroughly in the fall, and promptly remove any diseased plants. Mealybugs, spider mites, and whiteflies can also be a problem.