Choose a 2- to 3-gallon container that has one or more drainage holes and a drip tray. Each calendula plant will spread to about 1 foot wide at maturity.
Fill the container within 2 to 3 inches of the rim with organic potting soil. Water the soil thoroughly.
Press three to five shallow holes, not more than 1/4-inch deep, in the soil with your finger. Space the holes equal distances from each other.
Place one or two calendula seeds in each hole. Cover the seeds lightly with soil.
Water the seeds until they are saturated, then water regularly throughout the growing season. Calendulas like to grow in moist, but not soggy, soil.
Fertilize the calendula plants once or twice during the summer with a liquid or granular fertilizer, following the label directions.
Deadhead the calendula blossoms regularly to promote continuous blooming.