The best time to plant marigold seeds is after the last frost date in spring, when soil temperatures have warmed to at least 65°F (18°C). This typically falls around April to May depending on your local climate. For direct sowing outdoors, wait until nighttime temperatures consistently stay above 50°F (10°C) and the risk of frost is over—usually about one to two weeks after the final frost date. Marigold seeds germinate best when soil temperatures are between 70-75°F (21-24°C), with germination occurring in 5 to 8 days. If you want a head start, you can plant marigold seeds indoors about 6 to 8 weeks before the last expected frost. Start seeds in seed trays or pots with seed- starting mix, sow seeds about 1/4 inch deep, and keep them warm (70-75°F) with plenty of light. Once seedlings are strong and all frost danger has passed, harden them off by gradually exposing them to outdoor conditions before transplanting them. In summary:
- Direct sow outdoors: After last spring frost, when soil is warmed and night temps stay above 50°F (10°C)
- Start indoors: 6 to 8 weeks before last frost date
- Soil temperature ideal for germination: 70-75°F (21-24°C)
- Seed depth: Lightly cover with 1/4 inch soil for good germination
These guidelines help ensure successful marigold seed germination and robust plants for your garden.
