Calendulas & Their Germination Times

Site Preparation

• Well-draining soil and six or more hours of daily sunlight ensure good germination and healthy calendula growth. Calendulas require a soil pH between 6 and 7, which is average in most established flower beds. The plants grow best in rich soil, so amending the site with a 2-inch-thick layer of compost before planting improves both moisture and nutrient quality. A calendula can grow without fertilization during the growing season, but it benefits from the addition of 2 teaspoons of 16-16-8 fertilizer mixed into the top 6 inches of each square foot of garden bed.

Sowing

• When soil temperatures are above 60 degrees Fahrenheit, calendula seeds will germinate. Sow the seeds on the surface of the garden bed, spacing them 2 to 3 inches apart in rows set 12 inches apart. Cover the seeds with a 1/4-inch layer of soil. Calendula will not germinate if exposed to light. Mist the bed daily with a fine spray of water so the soil remains moist. After a week or two, when the seeds germinate and begin growing, you can reduce watering to when the soil surface dries. The seedlings require thinning once they grow about 4 inches tall so that the remaining plants stand 8 to 12 inches apart in the row.

Transplants

• Calendula seeds germinate readily indoors in pots started six weeks before the last spring frost, which allows you to get a head start on the growing season. Sow two seeds per 3-inch seedling pot, and keep the soil above 60 degrees until they sprout. Provide indoor plants with six hours of sunlight after germination, and water when the soil surface dries. You can transplant the calendula seedlings to the garden once the soil reaches 60 F, spacing the transplants 12 inches apart in all directions. Always plant calendula transplants at the same depth they were growing at previously.

Basic Care

• Calendula plants primarily require regular watering once they germinate and begin growing well. Providing about 1 to 1 ½ inches of water a week, from irrigation or rainfall, is usually enough. One inch of water should moisten the top 6 inches of soil. Mulching the garden bed further helps retain soil moisture and minimizes weed problems. Pinching off dead flowers encourages ongoing bloom. You can also cut the plants back to within 6 inches of the ground if they stop flowering at midsummer, which forces new growth and more flowers.