How to Start Lemon Balm From Seed
Lemon balm is a hardy perennial herb that can be started from seed, although germination may be uneven. Seedlings grow slowly at first but become vigorous plants after establishment.
Start indoors or direct sow?
Start indoors and transplant for the most reliable early-season plants, especially in short-season areas. Direct sowing is possible after frost, but tiny seedlings can be harder to manage outdoors.
When to start Lemon Balm seeds
Start indoors 6 to 8 weeks before the last spring frost. Transplant after the last frost, or direct sow outdoors around the last frost once soil has warmed somewhat.
How to sow the seeds
Surface sow seeds on moistened sterile seed-starting mix in small cells or shallow trays, then press them in without covering, since light aids germination. Keep the tray covered with a humidity dome until sprouts appear, then remove it and provide bright light.
Germination
Germination usually takes 7 to 21 days. Keep the mix consistently moist and warm, around 65 to 75 F, without waterlogging it.
Seedling care
Provide strong light for 14 to 16 hours daily indoors and water from below or at soil level when the surface begins to dry. Thin to one seedling per cell, use clean containers and airflow, and avoid excess moisture to prevent damping off.
Transplanting & hardening off
Harden seedlings off for 7 to 10 days, then transplant after frost into sun to partial shade and well-drained soil. Set plants at their original depth and space them about 18 to 24 inches apart.
Tips
Do not let seed trays dry out before germination, because the surface-sown seed is vulnerable. Remove flower buds if you want to encourage leafy growth, and consider containers if you want to limit spreading.
General seed-starting guidance for US home gardens; timing depends on your local frost dates and variety. Page updated Aug 4, 2026.