A herb from the mint family, rosemary (Rosmarinus officinalis) has leaves that are used to flavour poultry, leafy greens, stews, soups and sauces. It grows in USDA Hardiness Zones 7 through 11, although some plants survive in Zone 6. Zones 7 through 11 encompass most of the southern and southwestern states, as well as the coastal areas in the west.
Propagation and Transplanting
When grown from seeds, rosemary is slow to cultivate. For optimal growth, use stem cuttings, layering or division when planting. If your rosemary is potted, transplant the shrub twice a year for growth stimulation. If the shrub becomes too large for the pot, prune off the lower 2 inches of roots when the soil is exposed. For indoor gardeners who do not want to worry about pruning for size, a good rosemary cultivar to try is Blue Boy.
A mature rosemary shrub reaches 3 feet in height and 2 feet in diameter by its second season, although blooming does not occur until year two. Potted rosemary remains roughly the size of the container, as long as you prune regularly. If your rosemary's growth rate slows, try adjusting the sunlight. Rosemary shrubs require six to eight hours a day, so indoor plants may need additional artificial light or a good window with plenty of light. Flowers, which are blue or lilac in colour, bloom annually in early summer.
Once an outdoor rosemary shrub becomes dense with foliage, it can be pruned back several inches once or twice a year. After pruning, lay out the strips on a screen to dry before pulling off the spicy leaves and storing them. The Alabama Cooperative Extension recommends topiary or hedge shapes, as rosemary is dense enough to have its size and shape manipulated. One of the best specimens for topiary shaping is the Shimmering Stars rosemary cultivar, according to the website Fine Gardening.
Rosemary, whether grown indoors or out, requires full sun. If planting outdoors, allow for 4 to 6 feet of growing height and 3- to 4-foot spacing between specimens. Rosemary does not transport well, so it should not be moved once it has reached maturity, although regular transplanting is fine. In winter climates, moderate protection, such as wind-resistant tarps or covers, should be implemented to prevent frost damage. When it comes to soil, both indoor and outdoor rosemary require well-draining, light soils. See Resources for a chart to help you determine your area's hardiness zone.