Remove the debris, weeds and rocks from a site situated in full sun with moist soil that drains well. Marigolds do not grow well in standing water. Loosen the soil 6 to 8 inches deep with a shovel. Break the dirt clumps up with the edge of the shovel. The soil needs to be light and small in texture.
Spread a 1-inch layer of compost on top of the soil. Mix the compost into the loosened soil and rake smooth. Space the Mumsy marigold seeds 6 to 8 inches apart by tapping the side of the package to gently knock the seed out of the pack.
Cover the seeds with a quarter inch of compost, sand or vermiculite. Lightly covering the seeds allows the heat from the sun to warm the marigold seeds. Do not pat the soil down over the top of the seeds. This causes compacted soil and the seedlings have trouble to breaking through the crust. Mumsy marigold seeds germinate in seven to 10 days when temperatures are 70 to 75 degrees Fahrenheit.
Mist the Mumsy marigold patch with water to keep the soil moist until the plants have ground 4 inches. When the seedlings are 3 to 4 inches tall, pull the weaker, thinner ones. Space the marigold plants 8 to 12 inches apart to ensure good growth and air circulation.