Marigolds produce bright yellow, orange or red blooms. They come in tall African varieties or shorter and bushier French varieties. These annual flowers bloom from spring until the first frost in fall, adding a spectacular show of color to your beds, borders and outdoor containers. Disease- and pest-resistant, marigolds require minimal maintenance once planted in order to thrive. Start marigolds indoors in spring 6 weeks before the last predicted frost date in your area.
Fill seed-starting flats or pots with potting soil to within 1 inch of the container's rim. Make your own potting mix by combining 1-part peat moss with 1-part sterilized compost and 1-part coarse sand.
Sow seeds on the soil surface. Place three seeds per pot or space seeds 3 inches apart in flats. Cover with a 1/4-inch layer of soil.
Water the soil lightly, sprinkling the water on so it doesn't disturb the seeds. Cover the containers with a layer of plastic film wrap and place in a warm room to germinate.
Check containers daily for signs of germination, which takes 7 to 14 days. Remove the plastic wrap as soon as seedlings appear and place them in a warm, sunny window.
Keep the soil moist at all times. Provide 6 to 8 hours of natural light per day or place under grow lights for 12 hours a day.
Transplant marigolds outside once all danger of frost has passed. Place plants in containers outside for 2 hours the first day then bring back inside. Continue placing them outside each day for a week, gradually increasing the time outdoors until they are spending the whole day outside at the end of 7 days.
Plant marigolds in a well-draining garden bed in full sun. Space French varieties 6 to 9 inches apart and space African varieties 18 inches apart.