How to grow rosemary

Salvia rosmarinus · Lamiaceae · Herb

Rosemary is a warm-season herb in the Lamiaceae family, usually started indoors and set out as transplants. It wants full sun (six or more hours of direct light) and little supplemental water once established. From sowing to first pick is about 90–120 days. It shrugs off a light frost but a hard freeze will damage it.

Grower’s note: Best bought as a plant - seed germinates slowly and unevenly. A woody perennial only where winters stay above about 0 F (roughly Zone 7); colder than that, grow it in a pot and bring it indoors. Full sun, dry feet, no rich soil.

Sowing

Sow barely covered — the seed needs light to germinate, into soil between 60–80°F — germination is quickest near 70°F. It is slow and often erratic to germinate (14–28 days). For an early crop, start seed indoors about 10 weeks before your last spring frost and grow it under bright light.

Spacing & layout

Give each plant about 24″ along the row with roughly 30″ between rows. On a square-foot grid that is one plant per 4 square feet. Allow at least 12″ of loose, workable soil for the roots. It grows well in containers at least 12″ deep.

Fitting it to your season

Rosemary needs roughly 90–120 frost-free days to crop. Where the season is shorter than that, start it indoors and choose the earliest-maturing varieties, or grow it in a container you can move under cover on cold nights. In long, hot-summer regions it can often be planted twice — once in spring and again in mid-to-late summer for a fall harvest.

Quick facts

When to plant rosemary

Companions

Common problems

Pests: aphids, spittlebug, spider mite.

Diseases & disorders: root rot, powdery mildew.

Same family (Lamiaceae)

Rotate these so they don’t follow each other in the same bed year to year.

Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.