Calendula officinalis, commonly known as pot marigold, has bright yellow and orange flowers. A hardy annual, it blooms from late spring through mid-fall. Calendula grows up to 2 feet high with a spread of about 6 inches. It requires full sun and moist conditions. Varieties include flashback, zeolights and red splash. Each has different colors and bloom sizes.
Though originally used by Indian and Arabic groups, calendula was also valued by the Egyptians and Greeks. In India, marigold wreaths crowned the gods and goddesses. The Egyptians believed it was a rejuvenating herb and the Greeks utilized it for culinary purposes. By the American Civil War, one of the modern uses, wound treatment, was being developed on the battlefield.
Sow calendula from seed. If started in the fall, winter, or before the soil has warmed in the spring, plant indoors in pots or plug trays. Keep moist but not soggy. If kept in a cool location, a heat mat will speed germination and provide better growth. Place the growing plants under a grow light or in a sunny window. Transplant outside after risk of frost has passed. Space plants 6 to 12 inches apart.
To start directly in the garden, prepare the site by removing weeds and amending the soil with compost. Plant seeds 1/2 inch deep and space them 6 inches apart. Calendula needs temperatures between 60 and 70 degrees and regular watering to germinate. Germination takes up to two weeks.
Calendula requires little upkeep and is fairly easy to grow. The plants do well in most soil types, but do need regular watering. Be careful not to over water, however. Spread a light mulch to prevent weeds and retain moisture. Deadheading after flowers have died back encourages more flowers to form. Pot marigold does self-seed if seeds are not removed. Seeds can be dried and saved for the next planting. Slugs will eat the young plant's leaves. Be vigilant and set traps for them. Powdery mildew can develop on leaves--remove and dispose of affected leaves.
Uses of calendula range from culinary to medicinal, although the National Institutes of Health suggest more research is needed to confirm benefits of the plants. The antiseptic, antibacterial and antifungal blooms might promote healing. Use it in salves, creams and compresses and apply to burns, stings and shallow wounds. Calendula shows possible benefits in treating pain in ear infections and dermatitis during breast cancer radiation therapy, though further studies are needed for confirmation. In cooking, calendula is used primarily for color. Add the flower petals to butter, cheese, soups and rice to add saffron-like color.