Harman US

Winter Sowing

Seed Starting

Winter sowing is a method of starting hardy seeds outdoors in covered containers during the cold season. It uses natural temperature changes and light to trigger germination when conditions become suitable.

How to do it

Fill a vented, weather-resistant container with moistened growing medium and sow seeds according to their depth needs. Close the container, label it clearly, and place it outdoors where it will receive precipitation and light. Check periodically to be sure the medium does not dry out completely and that ventilation remains open. Open containers more as weather warms, then transplant seedlings after they are established.

Timing

Winter sowing is typically done in winter, well before the average last spring frost date. It suits many hardy perennials, native plants, and cool-season annuals that tolerate cold exposure. Tender warm-season crops are usually better started later under protected conditions.

Tips

Choose species that match your local climate and cold tolerance. Secure labels well because sun and moisture can fade ink. Containers can warm quickly on sunny days, so ventilation is important as spring approaches.

← All seed starting guides

General guidance for US gardens. Timing depends on your local frost dates and hardiness zone. Page updated Aug 4, 2026.