The Best Time to Plant Rosemary

Seed Propagation

• Growing rosemary from seed is the most difficult option. Even with fresh, healthy seeds, they are slow to germinate and can take up to three months to emerge from the soil. Seeds generally produce weaker plants than those started with seedlings or cuttings. For best seed propagation, soak the seeds in water for 24 hours before sowing and plant the seeds in April, after the last frost has passed.

Seedlings

• Rosemary seedlings purchased from a nursery in the spring should be nurtured indoors on a sunny windowsill for several weeks until their roots have developed and new growth appears on the stems. In June, transplant the seedlings to a bright spot in the garden or into a container with good drainage and enough depth for 5 or 6 inches of root growth.

Plants From Cuttings

• The best way to grow rosemary is from cuttings. When the mature rosemary plant is in its fastest and most prolific stage of new growth, around May or June, cut or tear one or two tender 3-inch shoots from the plant, right below the spot where the leaf joins the stem. Remove about one-half inch of the lower leaves and shove the cuttings into a 3- or 4-inch-diameter pot filled with potting soil. Set the pot into water so the soil is saturated by absorption through the holes in the bottom of the pot. Cover the pots with plastic and set them in a warm spot until the roots have fully formed, about 8 weeks, watering occasionally to keep the soil moist but not soggy. Transplant the plants to the garden or containers when the root balls are fully formed.

Care and Maintenance

• Once you have grown a hardy, healthy rosemary plant or bush, it should last you 10 to 20 years. Rosemary is one of the toughest herbs and thrives in most soils, as long as it has ample room for root growth and the root is not disturbed. An equal mixture of potting soil and sand is ideal for rosemary. Water rosemary when the topsoil is dry, but avoid overwatering. Rosemary holds up well during hot and cold weather but should be sheltered from frost. Prune the plant to keep it bushy, and if it becomes spindly, stake it to keep it upright.