African marigold (Tagetes erecta) is the tallest marigold of the group, which includes Scotch, French and triploid. The plant can get up to 36 inches tall and primarily comes in golden or orange but may also be mahogany. Blooms may be 1/2 to 4 inches across and produce for some months if deadheaded. African marigold is heat tolerant once established. Marigolds can only be propagated from seed. African marigold is an annual, but you can easily save seed to spread the flowers into the following season.
Sow indoors
1. Fill a seed flat with a seed-starter mix and sow the seeds on the surface of the soil. Press them in slightly and mist the flat until it is evenly wet.
2. Place the lid on the flat and keep the soil temperature between 75 and 80 degrees Fahrenheit. Continue keeping the flat moist but not soggy until germination. Move the flat to a sunny window and grow the plants until they are 6 to 8 inches tall.
3. Transplant the seedlings to a sunny, organic-rich bed. Start another batch of seedlings to ensure a constant supply of marigolds. Spread out the plants with at least one foot between them. They will fill in and spread as they grow.
Sow outdoors
1. Allow the flowers to turn into seed at the end of the season. When the seed heads have dried, pull the flowers off the plant. Rake a seed bed and add 2 inches of compost.
2. Crush up the dried flower heads and sprinkle the seed over the prepared bed. It doesn’t matter that the dried chaff mixes in with the seeds. Rake the bed again and sprinkle 1/8 inch of sand over it. Water the bed.
3. Keep the bed evenly moist until the seeds germinate. After the seedlings have two sets of true leaves, separate them out of the bed to leave 12 inches between them. Plant any you remove in another area to spread the African marigold. (Adapted from ehow)
