Sow indoors mid-February to mid-April. Transplant or direct sow starting in late May, once soil has warmed. Starting indoors is more reliable. Use bottom heat to maintain an optimal soil temperature of 27-32°C (80-90°F).
Most nurseries grow rosemary from cuttings, not seeds. Germination is notoriously low, so plant more seeds than you plan to grow on. Sow them barely covered with sterilized seed starting mix over bottom heat. Once germinated, rosemary is highly prone to damping off, so keep watering to a minimum, provide bright light, and ventilation. Keep each plant in its own pot for the first winter and offer them protection from severe cold. Transplant to the garden the following spring at a spacing of 60-90cm (24-36?).
If growing rosemary in containers, provide monthly feedings of liquid fertilizer. Keep watered in hot weather. Mulch around all rosemary plants as cold weather approaches. If their roots freeze in times of hard frost, the plants will die.
Harvest individual leaves by pulling them off the plant. Harvest branches or stems for drying by cutting with a clean, very sharp knife. Scissors may crush the plant’s tissues at the cut end.
Rosemary is a good companion for beans, Brassicas, and carrots.