Calendulas, also known as pot marigold, are members of the Asteraceae or sunflower family. Calendula is quite adaptive, easy to grow from seed, edible, and a great cut flower that blooms prolifically, even after a light frost. Calendula’s name comes from calends, a Roman word that refers to calendar because of their belief that it bloomed on the first day of the month.
Calendula has a long history of medicinal use. The plant contains chemicals that are thought to heal wounds by aiding in new tissue growth and decreasing swelling. It has been used to treat sore throat, cramps, fever, stomach ailments, and many other conditions. If you were wondering how to grow calendula from seed, you’ve come to the right place!
General Sowing
When to Sow Outside: Cold Climates: 2 to 4 weeks before your average last frost date. Mild Climates: Early spring for summer bloom and late summer for winter bloom. Ideal soil temperature for germination is 68°-85°F.
When to Start Inside: 4 to 6 weeks before your average last frost date; recommended for cold climates.
Indoor Sowing
Use a lightweight seed starting mix/media (sterile and lighter than potting mix), and sow seeds 1/4″-1/2″ deep. Sow 4 seeds per pot, thinning to the strongest plant once leaves appear (clip extra plants at the soil level using scissors).
The strongest plant may not be the tallest; look for thick, strong stems and deep color. By thinning early, you minimize the negative impact of crowding, like stretching for light. Read about more indoor sowing tips.
Containers
Containers should be clean, sanitized, and have drainage holes. If you choose to sow in cell packs, you may need to up-pot seedlings once into larger containers before transplanting outside.
Transplanting
After hardening off, transplant seedlings at the spacing indicated on the seed packet.
Outdoor Sowing
Sowing Preparation and Spacing
Choose a full to part sun area and amend the soil as needed. Calendula doesn’t need particularly rich soil to thrive, but it does need good drainage; avoid planting in an area that remains soggy during the growing season.
Thinning
Thin seedlings when 2″ tall according to the seed packet suggestion.
Water
Very adaptive; can handle most soil types but needs good drainage.
Fertilization
Not usually necessary.
Weeding
Keep plants well weeded. Weeds compete with crops for light, nutrients, and water, and can harbor insects and diseases.
Special Care
Once plants have at least 4 sets of leaves, clip the growing tip to encourage more branching and flowers. Water soil, not foliage, to help prevent mildew. Remove spent flowers regularly to encourage blooms and prolong the bloom period. This also keeps plants from reseeding.
Harvesting
For longest vase life, cut stems when blooms just begin to open, and petals have not yet laid flat. Change vase water frequently. The best time to harvest flowers for culinary use is in the summer, in the heat of the day when the resins are high, and the dew has evaporated. Pinch off flower heads, then gently pull out the petals.
Common Pests and Diseases
Aphids are particularly fond of calendula, which makes it an excellent “trap crop” because it draws the pests away from other plants; thus, it could be a good companion plant for your vegetable garden.
Aphids can be sprayed off plants with a strong stream of water or killed on contact with insecticidal soap (an organic control which will also kill many other soft bodied insects).
Beneficial insects do need some pests present to provide them with food, so by allowing some pests to feed on calendula, you encourage beneficial insects to stay a while and take care of other pests.
