Rosmarinus means dew of the sea, reflecting the plant's native habitat on seaside cliffs in the Mediterranean region. Tough and versatile, rosemary grows most luxuriantly just above the tide line, braving wind and salt spraybut it will thrive inland, even enduring blistering sun and poor alkaline soil, if given moderate water and infrequent light feeding.
The many forms of rosemary vary in habit from stiff, erect types through rounded shrubs and squat, dense tufts to rock-hugging creepers. Height ranges from as low as 1 ft. to as tall as 6 ft. or more. Plants are thickly clothed in narrow, typically 1- to 1-in.-long, resinous, aromatic leaves that are usually glossy dark green above, grayish white beneath. Small clusters of - to -in. blossoms in various shades of blue (rarely pink or white) bloom through winter and spring; bloom occasionally repeats in fall. Leaves are widely used as a seasoning. Flowers also are edible; add them to salads or use as a garnish. Blossoms attract birds, butterflies, and bees and are the source of excellent honey. Deer leave rosemary alone.
Use taller types of rosemary as clipped or informal hedges or in dry borders with native and gray-leafed plants. Lower kinds are good ground or bank covers, useful in erosion control. Set container-grown plants or rooted cuttings 2 ft. apart for moderately quick cover. Foliage of most types has culinary uses, but flavor and fragrance vary; the best have a mildly pungent flavor and a complex aroma with sweet as well as resinous notes. Rosemary is also an ingredient in medicines, cosmetics, potpourri, and moth repellents.
Rosemary plants sold without names are frequently seedlings, which lack the uniformity of cutting-grown, named selections. Unfortunately, selection names are often confused, and many have synonyms; but named plants are still a better bet than nameless ones.
'Albus' ('Albiflorus'). Semi-upright grower, eventually reaching 6 ft. tall and wide. White flowers veined in pale lavender. Hardy to 0F.
'Arp'. One of the hardiest selections, taking temperatures as low as 10F. Discovered in Arp, Texas. Open grower to 4 ft. tall and wide; best with frequent pruning. Dark green foliage has a grayish tinge. Bright, medium blue flowers.
'Barbecue'. Grows 5 ft. tall, 23 ft. wide, has excellent fragrance for cooking; blue flowers.
'Blue Boy'. Young plant makes a dense, symmetrical mound 812 in. high, 1418 in. across, reminiscent of a dwarf spruce (Picea). Leaves are just in. long; flowers are light blue. Plant creeps with age, but habit becomes irregular; shear to maintain domed appearance. Good in rock gardens, pots. Pleasant fragrance and flavor. Tender.
'Blue Spires'. Strong vertical grower, to 56 ft. tall and as wide or wider with age; can be pruned for narrower form. Deep blue flowers. Superb landscape plant; makes tight sheared hedge. Excellent for seasoning.
'Chef's Choice'. Compact, mounding to 1218 in. tall and 12 in. wide. Selected for higher oil content and spicy flavor. Hardy to 10F.
'Hill's Hardy'. Compact, bushy plant grows semiupright to 5 ft. high and wide. Stiff foliage. Light blue flowers; repeat bloom in fall. Pleasant, light fragrance. Discovered by the late Madalene Hill of Round Top, Texas. Hardy to 10F.
'Huntington Carpet' ('Huntington Blue'). To 1 ft. high; spreads quickly yet maintains a dense center. Pale blue flowers. Best selection for ground or bank cover.
'Irene' ('Renzel's', 'Renzel's Irene'). Vigorous spreader that covers 23 ft. or more per year, mounding to 11 ft. high. Deep lavender-blue flowers. Reputedly one of the most cold-hardy prostrate selections.
'Lockwood de Forest' ('Santa Barbara', 'Lockwoodii', 'Forestii'). Resembles 'Prostratus' but mounds up to 2 ft. or more; has lighter, brighter green foliage and bluer flowers.
'Majorca Pink'. Initially erect to 24 ft. tall and 12 ft. wide; eventually twists into picturesque shape under the weight of its heavy seed crop, flopping to 34 ft. wide. Lilac-pink flowers. Slightly fruity fragrance.
'Prostratus'. To 2 ft. tall, with 4- to 8-ft. spread. Will trail straight down over wall or edge of raised bed to make a green curtain. Pale lavender-blue flowers come in waves from fall into spring. With age, tends to mound up and become woody and bare in center (except at seashore, where it remains lush throughout). Effective in hanging containers. Tender.
'Salem'. Dependable old selection with dense, erect growth to 3 ft. high and wide; lavender-blue flowers. Fairly cold hardy.
'Spice Islands'. Upright growth reaches 68 ft., making this a good screen or background. Large blue flowers, good fragrance. Once grown for commercial seasoning production.
'Tuscan Blue'. Vita Sackville-West's original, brought to England from Tuscany, had relatively broad (to -in.-wide), 1- to 1-in.-long leaves, deep violet-blue flowers, and upright habit to 67 ft. tall and 12 ft. wide. A plant long sold as 'Tuscan Blue' in the U.S. fits this general description but has light blue flowers; with age, it becomes woody and bare at the base. Some nurseries sell 'Blue Spires' under this name.
Good drainage is essential; lighten heavy soils with plenty of organic matter. Heavy feeding and too much water result in rank growth, subsequent woodiness. Control growth by frequent tip-pinching when plants are small. Prune older plants frequently but lightly; cut to side branch or shear. If plants become woody and bare in center, cut back selected branches by half so plant will fill in with new growth (be sure to cut into leafy wood; plants will not regrow from bare wood). Or discard plant and start over with a new one. Branches root wherever they touch the ground; creeping types will spread indefinitely, forming extensive colonies. To get new plants, root tip cuttings or dig and replant layered branches.
Cold hardiness varies considerably, depending on selection. In general, upright types are hardier, while prostrate ones (native to Majorca and Corsica) are more tender, suffering damage at 20F or even higher. In the Upper and Middle South, choose the hardiest types and shelter them from winter winds. Note that even the hardiest types can succumb to cold if they have wet feet. Beyond hardiness range, grow rosemary in pots and winter indoors on a sunny windowsill; or treat as an annual.