Rosemary
By Polly Nelson UCCE Master Gardener
Common name of plant: Rosemary
Scientific name: Salvia rosmarinus
Planting zone: Sunset zones 4-24
Size: 1-6 feet, depending on variety
Bloom Season: Late fall through spring
Exposure: Full sun
Pruning needs: As needed to shape and prevent woody stems
Water needs: Low, after first year
Snapshot: Fragrant, sun-loving and water-conscious, this plant can be a star in many places in your landscape. Blossoms are small, with colors in shades of blues to white, and the small spiky green leaves freely release aromatic oils.
Rosemary comes in two major categories - upright and low-growing. Upright varieties, such as ‘Tuscan Blue', grow as shrubs and hedges, and can range from 3-6 feet high.' Low-growing, ground cover varieties, such as ‘Irene' or ‘Prostratus', can be trained to cascade down garden walls.
Plant rosemary after the last frost in well-draining soil, in full sun, and space plants 2-3 feet apart for good air circulation. Allow soil to dry out between waterings; too much water invites fungal root diseases. Add compost when planting to provide supplemental nutrients. After which, this is plant does not need any additional fertilizers.
Rosemary can be pruned as a topiary for an eye-catching element to the garden, or it can be pruned simply to control size. New green growth will not develop from woody stalks. If your plant becomes bare in center with woody stems, stimulate new growth by removing selected stalks. The plant will fill in with new growth.
Propagate rosemary with seeds or cuttings. Seeds can be reluctant to germinate, however, and slow to grow., Alternatively, softwood cuttings can be gathered in early summer, or hardwood cuttings in the fall. Clip a few inches of new growth with at least 5 leaves, dip into rooting hormone, and place in a container of potting soil with good drainage. Mist daily, then check for roots after 2-3 weeks. Note that branches will root wherever they touch soil. This is especially common with ground cover varieties.
Rosemary attracts bees, hummingbirds, and other pollinators, but has few insect pest problems. Monitor for powdery mildew if the plant develops dense growth and humidity is high. Indoor container plants may attract spider mites or aphids, which can be dislodged with a steady stream of water to reduce populations.
Harvest rosemary for recipes any time of the year by snipping off the tips and adding whole stems or stripped leaves to your dish. Whether grown indoors or out, rosemary will certainly satisfy the senses.
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