Secrets to Growing Rosemary Plants

Climate for Rosemary

• Rosemary plants are hardy perennials in U.S. Department of Agriculture plant hardiness zones 7 through 9, where winters are mild, and are considered tender perennials elsewhere. Rosemary plants can withstand a light frost, but in northern areas where winters are harsh, these herbs are best grown in containers so that they can be pulled inside when cold weather sets in.

Germinating Rosemary

• Rosemary is temperamental when grown from seed, and with germination ranging between 15 and 20 days, it takes a patient gardener to be successful. Cuttings and air-layering from an established, vigorous parent plant are quicker and more effective propagation methods.

Where to Plant Rosemary

• For in-ground planting, choose a site that receives good air circulation and eight hours or, if in a hot climate, four to six hours of sunlight each day. Also, make sure the area is well draining. Space plants 12 to 18 inches apart. To grow rosemary in containers, presoaked clay pots that can comfortably support a 2- to 4-foot plant are recommended by Jo Ann Gardner, an herb gardener of 25 years and author of "Herbs in Bloom."

Soil for Rosemary

• Rosemary likes alkaline to neutral soil with a pH range between 6.0 and 7.5. For soil pH that is below 6.0, add pulverized eggshells or another lime source. Well-drained, sandy soils are also key for a thriving rosemary plant, and the soil should never be so compact that water collects around the bottom of the herb's roots.

Watering Rosemary

• Rosemary prefers to keep its feet dry, so it's best to only water when the soil a few inches deep feels dry. Do not overwater rosemary, as this inhibits the herb's growth. Container rosemary plants tend to dry out when kept indoors because of lack of humidity. Avoid drying out and eventually killing your rosemary plant by frequently misting its leaves with water. Another option is to spread some small pebbles on a saucer and pour water over the pebbles. Set the rosemary plant on the saucer; as the water evaporates it creates a curtain of humidity around the herb.

Fertilizing Rosemary

• Rosemary benefits from one or two light feedings per year. Fertilize once in the spring with a light, balanced fertilizer, like 20-20-20, and once more in the summer. Rosemary grows little or not at all in the winter and therefore needs no fertilizer in cold months.