How to Start Rosemary From Seed
Rosemary is a slow-growing perennial herb that can be started from seed, though germination is often uneven. Seed-grown plants may vary, so start extra seeds if you want several plants.
Start indoors or direct sow?
Start rosemary indoors and transplant it after frost danger has passed. Direct sowing is usually unreliable because the seeds are slow to germinate and young plants grow slowly.
When to start Rosemary seeds
Start indoors about 10 to 12 weeks before the average last spring frost. Set plants outdoors after the last frost, once nights are consistently mild.
How to sow the seeds
Sow seeds on the surface of a sterile, well-drained seed-starting mix and press them in lightly, as light can aid germination. Use small cells or pots with drainage, cover loosely with a humidity dome, and provide bottom heat if available.
Germination
Germination commonly takes 14 to 28 days, and some seeds take longer. Keep the mix evenly moist, not wet, at about 65 to 75 F.
Seedling care
Give seedlings strong light for 14 to 16 hours daily, ideally from a grow light placed close above them. Water only when the mix begins to dry at the surface, provide airflow, and remove the humidity cover after sprouting to reduce damping off.
Transplanting & hardening off
Harden plants off over 7 to 10 days, then transplant after frost into full sun and sharply drained soil. Handle roots gently and space plants so air can circulate.
Tips
Use fresh seed and sow more than you need because germination can be spotty. Do not overwater, rosemary seedlings are especially vulnerable in soggy mix.
General seed-starting guidance for US home gardens; timing depends on your local frost dates and variety. Page updated Aug 4, 2026.