How to grow Rosemary

Where to plant

Plant rosemary in full sun in light, sandy or gravelly, well-drained soil. It is drought tolerant once established and rots quickly in heavy, wet soil, so use a raised bed, a slope or a large pot where drainage is poor. Good air movement helps prevent powdery mildew.

Rosemary is a tender perennial, hardy to about zones 8 to 10. Hardier cultivars survive zone 7, and sometimes zone 6b with a sheltered, well-drained spot and winter protection.

• Florida, the Gulf South, Texas, the Desert Southwest and California: grows as a long-lived shrub. Plant in spring or fall; in Florida the main danger is summer rain and humidity, so drainage and air flow are essential.
• Hawaii: grows well in dry, sunny spots; avoid wet sites.
• Mid-South, Mid-Atlantic, Southern Plains and the Pacific Northwest: choose a hardy cultivar, plant in spring so it establishes before winter, and give it the warmest, best-drained spot.
• Northeast, Midwest, Mountain West, Northern Plains and Alaska: too cold to overwinter outdoors in most places. Grow it in a pot outdoors in summer and bring it into a cool, bright room or sunroom before hard frost.

Choosing a variety

• Upright types such as Tuscan Blue are vigorous and best for cooking.
• Arp, Madalene Hill (sold as Hill Hardy), Athens Blue Spire and Miss Jessop's Upright are the hardiest, surviving to about zone 7.
• Trailing or prostrate rosemary spills over walls and pot edges and is a little less hardy.

How to plant

1. Buy a plant or root a cutting; seed is slow and the seedlings vary.
2. Plant at the same depth as the pot, in well-drained soil without added rich compost or manure.
3. Water in, then water only when the top inch or two of soil is dry while it establishes.
4. Mulch with gravel rather than bark, which keeps the crown dry.

Watering and feeding

Once established, rosemary needs watering only in long dry spells. Water deeply and let the soil dry out between waterings. In pots, water when the mix is dry an inch down, and never leave the pot sitting in a saucer of water.

It needs little or no fertilizer. Rich feeding gives soft, sappy growth with less flavor.

Pruning and care through the year

• Trim lightly after flowering and through the growing season to keep the plant bushy. Avoid cutting back hard into old, bare wood, which is slow to resprout.
• In zone 7, plant in a sheltered spot near a south-facing wall and mulch around the base before winter.
• Indoors in winter, give it the brightest window you have in a cool room, water sparingly and keep air moving to prevent powdery mildew.

Harvesting

Snip the soft green tips and the top few inches of stems as needed, all year in mild areas. Take no more than about a third of the plant at a time. Sprigs keep a week or two loosely wrapped in the fridge, and they dry and freeze well.

Growing in pots

Use a pot at least 10 inches wide with drainage holes, and a gritty mix such as potting mix with added sand or perlite. Terracotta helps the roots dry between waterings. Repot into a slightly larger pot every year or two.

Using it

Use rosemary with roast lamb, chicken, potatoes and bread, or in marinades and infused oils. Woody stems stripped of their leaves make flavorful skewers for the grill.

Propagation and saving seed

Rosemary is best propagated from cuttings. Take 3 to 4 inch tip cuttings in spring when growth is vigorous, strip the lower leaves, and root them in a free-draining mix kept lightly moist.