Spread 2 to 3 inches of compost, peat or rich loam over a full-sun, well-draining garden bed. Till the organic matter into the soil, so it provides improved drainage and soil quality.
Dig the planting holes 1 inch deeper than the marigolds' pots' depth. Space the holes 12 inches apart for short African marigolds and 18 inches apart for tall varieties.
Turn the pot upside down and gently knock the marigold from the pot. Support the soil with your hand as the plant slides out of the pot.
Set the plant in the prepared planting hole. The marigold should sit ½ to 1 inch deeper in the garden bed than it was growing at in the pot.
Fill the hole in with soil around the marigold roots. Watering the bed thoroughly after planting helps settle the soil around the plants.