ROSEMARY
Rosemarinus officinalis.
A member of the Lamiaceae (mint) family.Botany. Rosemary is a perennial evergreen shrub whose ash-colored scaly bark and green needlelike leaves give it an overall grayish green appearance. Leaves resemble needles, are from one-third to one and one-half inches long, opposite, narrow, thick, and leathery, with dark green upper surfaces and powdery white and hairy underneath, and a prominent vein running down the middle of each leaf. Flowers, growing in clusters of two or three along branches, are pale blue, half an inch long; the upper lip appears notched with two lobes and a lower lip with three lobes. Fruits are very small, spherical nutlets with smooth surfaces. Plants can grow upright or prostrate, five to six feet outdoors and two to five feet indoors. Fragrance is pungent and piny.
Use. Native to the hills along the Mediterranean, Portugal, and northwestern Spain, rosemary is now widely cultivated. Rosemary, fresh and dried, has medicinal, culinary, dye, and ornamental uses.
Long included in herbalists' stores, rosemary has been regarded as antiseptic and astringent and prescribed for depression, headaches, muscle spasms, pains, sores, eczema, bruises, wounds, and to restore digestion.
Both the flowers and leaves of rosemary can be used in cooking and for garnishes. Dried or frozen rosemary is stronger than fresh. Woody branches can be used as skewers for barbecues. Rosemary oil is used to add a piny scent to soaps, creams, lotions, perfumes, toilet waters, potpourris and sachets. As a dye, rosemary produces various shades of yellow-green with wool.
Climatic Requirements. Rosemary can be grown outdoors in climates where winter temperatures do not drop below 27°F; 10° Ffor the alba variety. Although rosemary is drought tolerant outdoors, it is sensitive to both drought and overwatering indoors. Note that 'drought tolerant' relates to survival, not to the rate of growth under drought stress; good production requires adequate water.
Propagation and Care. Rosemary does well in full sun in well-drained soil with a pH of 6.0 to 7.5. Warm, dry summer climates are ideal; rosemary does not do well where winters are cold and wet unless it grows in a protected site. Good drainage is essential, as roots easily develop root rot.
Cuttings and layerings from established plants make the best propagation material. Root cuttings in a sand/loam/leaf mold mixture in a cold frame or cool greenhouse. Set three feet apart outdoors in the same type of soil.
Rosemary can be started from seed, but germination rates are very low, even at an optimum of 60°F for 14-21 days; and it takes up to three years to produce a bush sizable enough for harvesting. In addition, plants grown from seed are not as robust as cuttings and layerings: stems are softer, branches are weaker, and leaf color lacks sheen and intensity.
Fertilize infrequently or if soil is poor; too much fertilizer reduces flowering and fragrance.
Harvest. Harvesting can be done throughout the year, but care should be taken to not remove more than 20 percent of the growth at a time. Volatile oils are most potent just before blooming. To dry leaves, cut individual branches and strip the leaves from the branches onto screens or paper in a shady place with good air circulation, or dry whole or partial branches for decorative use.
Postharvest Handling (section by Marita Cantwell). Increased use of fresh herbs for culinary and other purposes has also increased the demand for high quality. The successful marketing of high quality fresh culinary herbs requires extreme care and attention to postharvest handling conditions.
All the postharvest principles that apply to leafy green tissues apply to the handling of fresh herbs. Temperature is the single most important factor in maintaining quality after harvest. Despite the diverse botanical origin of the fresh herbs, the optimum postharvest temperature for fresh thyme, oregano, rosemary, mints, sage, parsley, cilantro, savory, marjoram, dill, and tarragon is 32 F (0 C). Under controlled conditions, a shelf life of 3 to 4 weeks can be achieved at this temperature. With a temperature of 41 F (5 C), a minimum shelf life of 2 to 3 weeks can be expected.See Figure 1. If herbs are harvested early in the morning, the need for cooling is minimized. If harvested later, the appropriate cooling method depends on the type of herb. Most respond favorable to room and forced air cooling. Herbs have also been successfully vacuum-cooled. A simple forced air pre-cooler can be constructed for small operations that requires only an adequate coolroom, a fan, and some simple carpentry.
After temperature, prevention of excess moisture loss is the second most important postharvest factor affecting the quality and shelf life of herbs. Most herbs respond favorable with very high humidity (>95%). Some herbs can be held successfully in water (basil, mints, tarragon), whereas water loss in most can best be controlled by packaging and maintaining high humidity in the environment. Lowering the holding temperature to the recommended levels also greatly reduces water loss.
Herbs can be packaged in bags designed to minimize water loss. When herbs are packaged this way, it is particularly important to maintain constant temperatures, to reduce condensation inside the bag and the consequent risk of fungal or bacterial growth. The bags may be partially ventilated with perforations, or may be constructed of a polymer that is partially permeable to water vapor.
The relative humidly in the packing area, cold rooms, and transport vehicles should be maintained at a high level (>95%) where practical.
Ethylene gas is another factor which limits the shelf life of leafy tissues. Ethylene causes yellowing of leaves, and an increased rate of deterioration. It is possible to routinely find one to three ppm ethylene in the environment surrounding fruits and vegetables during commercial handling. Young growing herb tissue responds to ethylene (5 ppm), whereas little effect was observed in mature herb cuttings. In addition, holding the herbs at the recommended temperatures also greatly reduces their ability to respond to ethylene in the environment.
Careful handling to avoid physical injury to the leafy tissue of the fresh herbs is also important. Rigid clear plastic containers such as those sometimes used for sprouts may be used for soft herbs. "Pillow packs" (plastic bags which are partially inflated when sealed) may be an alternative packaging technique. Careless handling results in tissue discoloration, as well as increasing sites for pathogen attack. Growth of microorganisms can also be reduced by proper temperature management and good hygienic practices in the field and packing station. Chlorinated water can reduce microbial load if water is used during handling.
Varieties/Cultivars:
Rosmarinus officinalis 'Benenden Blue' - upright growth, blue flowers, very narrow leaves
R.o. 'Argenteus' - upright growth, slightly silvery foliage
R.o. 'Arp'- upright growth, pungent but without a strong and sharp scent, hardy to -10°F.
R.o. 'Aureus' - upright growth, yellow-tones leaves
R.o. 'Blue Boy' - upright growth, blue flowers
R.o. 'Blue Lagoon' - upright growth, blue flowers
R.o. 'Blue Sprite' - upright growth, blue flowers
R.o. 'Collingwood Ingrami' - Wood rosemary - upright growth, dark blue flowers, shorter and plumper leaves, looser appearance with gracefully pendulous branches
R.o. 'Corsicus' - upright growth, blue flowers
R.o. 'Creeping' - prostrate growth, deep blue flowers, long branches that twist and curl and recurve, blooms almost continuously
R.o. 'Dutch Mill' - upright growth, slightly silvery foliage
R.o. 'Erectus' - upright growth, blue flowers
R.o. 'Fastigate' - upright growth, blue flowers
R.o. 'Golden Rain' - most compact and vigorous habit of any upright grower, gold and green variegated leaves, dark blue flowers, strong aroma
R.o. 'Gorizia' - upright growth, long and broad leaves double the size of other plants, medium blue flowers, gentle aroma, hardy to about 15°F.
R.o. 'Gray' - upright growth, pale blue flowers, grayish foliage, fairly broad leaf
R.o. 'Humili' - prostrate growth, blue flowers
R.o. 'Huntington Carpet' - prostrate growth, blue flowers
R.o. 'Joyce DeBaggio' - upright growth, similar to Golden Rain, hardy to 20°F.
R.o. 'Kenneth' - prostrate growth, blue flowers
R.o. 'Lockwood de Forest' or Lockwoodii' or 'Foresteri' or 'Santa Barbara' - prostrate growth, light blue flowers, lighter green foliage
R.o. 'Logee Blue' - upright growth, the most intensely blue blooms
R.o. 'Lottie DeBaggio' - upright growth, strong aroma, sparse foliage, very sensitive to overwatering, hardy to 5°F
R.o. 'Majorca Pink' or 'Majorca' or 'Roseus' or 'Roseus-Cozart' - upright growth, pink to amethyst violet flowers, produces long branches that twist around the plant and then cascade, blooms sparsely but almost continuously, hardy to 15°F
R.o. 'Miss Jessup' - upright growth, pale blue flowers, golden green foliage
R.o. 'Pine Scented' - upright growth, blue flowers leaves are narrow and light green, strong pine scent
R.o. 'Prostratus' or 'Lavandulaceus' - prostrate growth, blue flowers almost continuously, white stems, long branches that twist and curl and recurve
R.o. 'Rex' - upright growth, blue flowers, very striking appearance, almost black-green leaf color with white beneath, dynamic bloomer
R.o. 'Roman Vivace' - upright growth
R.o. 'Severn Seas' - upright growth
R.o. 'Trailing - prostrate growth, deep blue flowers, long branches that twist and curl and recurve, blooms almost continuously
R.o. 'Tuscan Blue' - upright growth, deep blue flowers, reddish stems, light medium green glossy short wide leaves thickly clustered on stems, fast grower, mild fragrance, may reach 10-12 feet, hardy to 15°F
R.o. var. alba or 'Albus' or 'Albiiflorus' - White-flowered rosemary - upright growth, white flowers, dynamic bloomer
R.o. var. prostratus 'Huntington Carpet' - Huntington carpet rosemary - prostrate growth, deep blue flowers, blooms throughout most of the year.
Seed/Cutting/Plant Sources:
Abundant Life Seed Foundation, PO Box 772, Port Townsend, WA 98368.
Applewood Seed Co., PO Box 10761, Edgemont Station, Golden, CO 80401.
Bountiful Gardens, 5798 Ridgewood Road, Willits, CA 95490.
W. Atlee Burpee & Co., 300 Park Avenue, Warminster, PA 18974.
Caprilands Herb Farm, 534 Silver Street, Coventry, CN 06238.
Comstock, Ferre & Co., 263 Main St., Wethersfield, CT 06109.
De Giorgi Co., Inc., PO Box 413, Council Bluffs, IA 51502.
Gurney's Seed & Nursery Co., Yankton, SD 57079.
Harris Seeds, 961 Lyell Avenue, Rochester, NY 14606.
Henry Field's Seed & Nursery Co., Shenandoah, IA 51602.
Indiana Botanic Gardens, PO Box 5, Hammond, IN 46325.
J.L. Hudson, Seedsman, PO Box 1058, Redwood City, CA 94064.
Lagomarsino Seeds, Inc. 5675-A Power Inn Road, Sacramento, CA 95824.
Le Jardin du Gourmet, PO Box 75, St. Johnsbury Center, VT 05863.
Nichols Garden Nursery, 1190 North Pacific Hwy., Albany, OR 97321.
Park Seed Co., Cokesbury Road, Greenwood, SC 29647-0001.
Pinetree Garden Seeds, Route 100, New Gloucester, ME 04260.
Otto Richter & Sons Ltd., Box 26, Goodwood, Ontario, Canada L0C 1A0.
Shepherd's Garden Seeds, 30 Irene Street, Torrington, CT 06790.
Stillridge Herb Farm, 10370 route 99, Woodstock, MD 21163.
Stokes Seeds Inc., Box 548, Buffalo, NY 14240.
Taylor's Herb Gardens, Inc., 1535 Lone Oak Road, Vista, CA 92084.
Thompson & Morgan, PO Box 1308, Jackson, NJ 08527.
Vermont Bean Seed Co., Garden Lane, Fair Haven, VT 05743.
References:
DeBaggio, Tom. "Spring Is the Season to Plan Your Christmas Rosemary Crop." The Business of Herbs. March/April 1985. pp. 1-3.
DeBaggio, Tom. "Growing Rosemary." Fine Gardening Magazine. July-August 1988.
Kowalchik, Claire, et al., eds. Rodale's Illustrated Encyclopedia of Herbs. Rodale Press. 1987. pp. 428-432.
Newcomb, Duane, and Karen Newcomb. The Complete Vegetable Gardener's Sourcebook. Prentice Hall Press. 1989. 408 p.
Organic Gardening Magazine, The Encyclopedia of Organic Gardening. Rodale Press, 1978. pp. 970-971.
Yang, Linda. "Rosemary, Right?" Horticulture. July 1985. pp. 46-49.
Cantwell, M. and M. Reid. Postharvest handling of fresh culinary herbs. Perishables Handling No. 60: 2-4. Vegetable Crops Dept., UC Davis. 1986.
Joyce, Daryl, Michael Reid and Philip Katz. Postharvest handling of fresh culinary herbs. Perishables Handling No. 58:1-4. Vegetable Crops Dept., UC Davis. Feb. 1986
Figure 1. Effect of holding temperature on the quality of rosemary after 1 (•) and 2 (n) weeks storage in perforated polyethylene bags. Visual quality was assessed on a five point scale (9 high, 1 low). From Joyce, Reid, Katz 1986.
Figure 2. Rosemary. Photo by Hunter Johnson.
By:Yvonne Savio, Vegetable Crops Extension, UCD and Curt Robinson, University Extension, UCD
Reviewed by Tim Hartz, 1/7/92
1/13/92