Germination Rate & Viability
Gently check the packet and you’ll find two numbers that matter most: germination rate and seed viability. Germination rate tells you the percent of seeds likely to sprout under ideal care. Should a packet shows 80 to 95 percent, you can expect plenty of healthy starts. Seed viability tells you how long seeds stay able to sprout. Most marigold seeds stay viable one to three years when you store them cool, dry, and dark. Germination time runs about 5 to 21 days, so give seedlings several weeks before replanting. To plan plant numbers, increase seeds sown based on the germination rate. Try a pre plant test with ten seeds on a moist towel in a sealed bag at warm room temperature for up to two weeks to check actual viability.
Growing Conditions Required
Now that you know how germination rate and seed viability affect your starts, it helps to match those facts with the right growing conditions so your marigolds actually thrive. You’ll want full sun, at least 6 to 8 hours daily, because marigolds bloom best with bright light. Plant in well drained, moderately fertile soil with pH near 5. 5 to 7.0 so roots stay healthy. Sow seeds shallowly, about 1/8 to 1/4 inch deep, and keep soil around 65 to 75°F for quick germination. Space plants according to size, 6 to 12 inches for compact types and up to 24 to 36 inches for tall varieties, to improve air flow. Water moderately, let the topsoil dry slightly between waterings, and deadhead spent blooms to keep flowers coming.
