Rosemary

Rosemary comes from the dry coastal hills of the Mediterranean, where it grows on stony ground within sight of the sea, and it has the needle leaves and resinous scent that go with a plant built to survive heat and drought. It was moved out of Rosmarinus and into Salvia in 2017, which is why nurseries still label it both ways. In a garden it is one of the most useful things you can plant: evergreen, aromatic, covered in bees in spring, and productive all year. In a pot it is straightforward as long as you resist watering it.

Light

Full sun, six hours a day or more. A wall that holds the day’s heat suits it particularly well. In shade it grows soft and open, flowers thinly and holds moisture in its centre, which is how a rosemary that has survived four winters dies in its fifth.

Soil and drainage

Free draining, and not rich. Sandy, gritty or stony ground is ideal, and this is a plant that does better with less. In heavy soil, plant on a slight mound with a generous handful of grit worked into the hole, and mulch with gravel rather than bark or compost, both of which hold water against the stem.

In a pot, use a gritty compost, a terracotta pot with a large drainage hole and no saucer. A pot that dries out fast is exactly what this plant wants.

Water and feed

Water a new plant through its first summer while it roots out. After that, an established rosemary in temperate ground wants nothing at all. In a pot, soak it and then let it dry right out, roughly every twelve days in summer and once a month in winter.

Do not feed a plant in the ground. A potted one benefits from a weak feed twice across the summer, simply because a pot eventually runs out of even the little it needs.

Pruning

Trim every year, after the spring flowering, taking about a third off the current season’s growth and keeping the plant to a rounded shape. Always cut into growth that still carries leaves.

Rosemary, like lavender, does not reliably reshoot from bare old wood. A plant that has been left for several years and has gone woody and open at the base cannot be cut back hard and rescued. If that has happened, take cuttings in late summer and replace it.

Sowing, planting and harvest

Seed is slow and variable. Sow in spring, March to May in the northern hemisphere and August to October in the southern, at about 20 degrees, and be patient.

Cuttings are far better and give the same plant. In late summer or early autumn take ten centimetre semi-ripe shoots, strip the needles from the lower half, and push them into gritty compost. They root in about six weeks. A low branch pegged down onto the soil also roots where it touches and can be cut free the following spring.

Harvest all year in a mild climate, taking sprigs from the tips rather than cutting into old wood. The flavour is strongest just before flowering.

Growing it in a cold winter

Where winters are wet as much as cold, a pot is often the better answer than the open ground, because it can be moved to the driest, brightest, most sheltered spot in the garden for the winter. Do not bring it indoors; a warm dark room is worse for it than a cold wet one.

Ailments

A soft brown base is wet roots. Powdery mildew follows still air in a crowded plant. Open leggy growth is shade or years without a trim, and cannot be fixed by cutting into bare wood. Brown needle tips in a pot mean it dried out completely. The ledger below has the rest.