Marigolds supply the garden with summer-long colour. Flowers are yellow, orange or red depending on the variety. The seeds germinate quickly and begin flowering in as little as six weeks. Planting the seeds at the right time ensures you get the longest season possible from these flowering annuals.
Indoor seeding gives the marigolds a head start on the gardening season so they are ready to bloom as soon as they are transplanted in the garden. Start the seeds indoors about six weeks before the last spring frost date in your areas. Plant marigold seeds in a seedling tray filled with a sterile potting mix. Marigold seeds are large and easy to handle. Sow each seed approximately 1.25 cm deep in the mix, spacing the seeds 5 cm apart in all directions. The seeds usually germinate within a week. Keep the potting mix moist and provide the seedlings with all-day sunlight.
Because marigolds germinate and reach maturity quickly, you can also start the seeds directly in the garden bed after frost danger is past in spring. Outdoor seeded marigolds begin blooming in early summer instead of in spring because of the delay in planting. Sow the seeds 5 to 10 cm apart in a well-raked garden bed. Raking the soil surface provides a loose, fine-textured bed which helps speed germination. Keep the bed moist during the germination process and continue to water regularly after the seedlings sprout.
You must transplant marigolds correctly if you start the seeds indoors to ensure they suffer no damage or shock once planted in the garden bed. Harden off the seedlings for one week before planting them into the garden bed. The hardening-off period helps the young plants adjust to the growing conditions outdoors. Set the seedlings in a protected area out of direct sunlight and away from high winds. Gradually move them into more direct sunlight each day until the plants are fully exposed. Once hardened properly, transplant the marigolds in the garden bed at the same depth they were growing in the tray.
Marigold seeds germinate well, but they can suffer fungal problems in the first weeks after sprouting. Indoor seedlings are more prone to damping-off than those grown in the garden bed due to less circulation and the weaker light indoors. Damping-off, usually caused by fungus, causes the seedlings to weaken and fall over until they eventually die. Water only when the soil surface begins to dry, as overly moist conditions aid fungal growth. Provide at least six hours of direct sunlight and avoid placing seedlings in humid areas of the home.