If you want flowers in the front yard by Memorial Day, marigolds started from seed inside in front of a sunny window make a good choice. Since it takes just 45 to 50 days until flowering from the day you plant the seeds, start seeds in a proven growing medium in early April. If you plan to sow seeds directly in the garden, wait until the danger of frost departs, then plant in full sun in moist, well-drained soil. In most areas of the country, flowers emerge from seed planted outdoors by middle to late June. Thin seedlings to 10 to 12 inches apart, and keep plants well-watered until they establish themselves.
Even though today's marigolds stem from three foundation marigolds, two of which are named for their perceived country of origin -- Tagetes erecta, or African marigold; Tagetes patula, or French marigold; and Tagetes teneuifolia, or signet marigold -- all began in the Southwest United States and South America. Marigolds established in Europe and Africa via Spanish and French explorers who transported seeds to the homeland.
French marigolds produce small, bushy plants with single or double flowers of orange, yellow, dark red and bicolor combinations, which bloom from spring until frost. African marigolds reach heights of up to 36 inches and produce flowers that span as much as 5 inches. Flowers present as the double variety in shades of yellow and orange. Signet marigolds produce yellow or orange edible flowers -- signets taste like spicy tarragon -- on bushy, lemon-scented plants. Small, single flowers completely cover the plant's lacy foliage by midsummer.
Marigolds as Companion Plants
Although many gardeners use marigold plantings to ward off destructive insects, the Alabama Cooperative Extension Service indicates marigolds may not accomplish this traditional role. Instead, the insects may attract destructive spider mites to an otherwise mite-free garden. ACES does acknowledge that marigold roots secrete a toxic compound that destroys nematodes in the soil. Nematodes feed on and destroy root systems of many plants.
Originally called "Mary's Gold," marigolds were named to honor the Virgin Mary. In the 1960s, U.S. Sen. Everett Dirksen of Illinois led an unsuccessful drive to make this small, unassuming bloom the national flower. Marigolds do not like cold weather, which make them susceptible to an early fall frost. Cover with newspaper or other protective material to extend bloom well into the fall season. Marigolds, especially the tall varieties, make good cut flowers.