These easy-to-grow annual flowers are also known as English marigolds or pot marigolds. Calendula repels a number of bad nematodes in the soil, but may attract slugs. Plant with tomatoes and asparagus. Please continue reading below for some tips on how to grow Calendula from seed.
Season & Zone
Exposure: Full sun to partial shade
Direct sow in early spring when light frost is still a possibility, and continue to sow every two to three weeks until early summer for fall flowers. Calendula is easiest from direct sowing, but can also be started indoors late winter for transplanting once daytime temperatures are steadily above 10°C (50°F). If starting indoors, maintain darkness and a soil temperature of 21°C (70°F) until germination occurs in 6-14 days, and then supply bright light to keep seedlings compact. Or direct sow in early autumn in Zones 8-10.
Sow seeds 5mm (¼”) deep, and aim for a spacing of 15-45cm (6-18″) between plants.
Calendula grows easily in any regular garden soil, and thrives in a pH range of 5.5-7.0. Pinch back young plants to encourage bushy growth. Occasional feeding is rewarded, but unnecessary. Keep plants watered, but try to avoid overhead watering as plants are susceptible to mildew. Deadhead regularly to prevent self-sowing.
Calendula repels a number of bad nematodes in the soil, but may attract slugs. Plant with tomatoes and asparagus.
More on Companion Planting.