Flowers & bulbs

How to Grow Calendula: Planting, Spacing, Care & Harvest

Quick answer

Start indoors 6–8 weeks before last frost, or direct sow just before last frost (Wisconsin; NC State). UNH waits until soil is about 60°F and heavy frost has passed. Sow about ¼ inch (UNH) or ¼–½ inch deep (Wisconsin); thin to about 16 inches (UNH). Deadhead for continuous bloom until heavy frost.

Calendula at a glance

PlantStart indoors: 8–6 wk before last frost; Direct sow: 1 wk before last frost to last frost
SunWisconsin: any well-drained soil in full sun; moderate watering; “Plants flower best when they are not heavily fertilized.”
WaterWisconsin: any well-drained soil in full sun; moderate watering; “Plants flower best when they are not heavily fertilized.”
SpacingWisconsin: sow ¼–½ inches deep; light inhibits germination; germination 5–15 days; use fresh seed.
Days to bloom30-50 days maturity (UNH); blooms July-Oct. (Purdue HO-80)
-9-8-7-6-5-4-3-2-1LF+1+2+3
■ Start indoors   ■ Plant out   ■ Harvest
Weeks relative to last frost (LF). Colored weeks show when our ZIP planner schedules each step.
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Updated

Not garden marigold. Pot/English marigold is Calendula officinalis; garden marigolds are Tagetes (Wisconsin). Claims that calendula deters insects as a companion plant are not scientifically verified (Wisconsin).

Orange calendula flower
Calendula (Calendula officinalis). Photo: H. Zell, Wikimedia Commons, CC BY-SA 3.0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Wisconsin: sow directly just before last frost date; for earlier bloom start indoors about 6–8 weeks before last frost; successive sowings for continuous bloom (Wisconsin Horticulture). NC State: start indoors about 6–8 weeks before last frost; plant seedlings just after last frost; direct sow just before last frost (NC State). UNH: direct sow in early spring once soil has reached 60°F and danger of heavy frost has passed (UNH).

Depth and spacing

Wisconsin: sow ¼–½ inches deep; light inhibits germination; germination 5–15 days; use fresh seed. UNH: cover with ¼ inch of soil; thin to 16 inches when seedlings are 1–2 inches tall; row spacing 16 inches; germination 10–15 days. Height depends on type (Wisconsin about 2 feet spreading; UNH compact 10–12 inches; NC State 1–2 ft).

Sun, soil and water

Wisconsin: any well-drained soil in full sun; moderate watering; “Plants flower best when they are not heavily fertilized.” NC State: average, moderately fertile, well-drained soils in full sun; some shade in hot summers OK; too much shade → leggy. UNH: evenly moist, well-drained loose soil; full sun. Heat: may languish in prolonged hot summer and recover when cooler (Wisconsin); cut back to rejuvenate in fall (NC State).

Care and harvest

Pinch vegetative buds when plants are several inches tall for bushier growth (Wisconsin; NC State). Deadhead regularly (Wisconsin; NC State); if flowers are not removed, plants may self-sow. Edible leaves and petals (Wisconsin); petals garnish/seasoning (NC State slightly bitter, tangy, peppery); UNH petals fresh or dried — do not eat nursery plants that may have been sprayed. Days: UNH 30–50 days. Cut flowers last longer if harvested when half open (UNH). Wisconsin: harvest whole tops or petals when fully expanded; dry out of direct sun.

Bloom season (Midwest annual table): Purdue Extension HO-80 lists calendula / pot marigold (Calendula officinalis) flowering season as July–Oct.

Pests and diseases (organic)

Wisconsin: generally few pests; may have aphids; occasionally cucumber mosaic virus; powdery mildew. NC State: slugs and snails (especially young plants), aphids, whiteflies; powdery mildew; cucumber mosaic. Organic: insecticidal soap or oil for aphids — thorough coverage; follow the label (UC IPM). Slugs/snails: handpick; iron phosphate bait — follow the label (UC IPM). Powdery mildew: spacing/air flow, avoid chronic leaf wetness, sanitation.

Related: ZIP planner · what flowers to plant in fall · organic pest control

Frequently asked questions

When do I plant calendula?

Start indoors 6–8 weeks before last frost, or direct sow just before last frost (Wisconsin; NC State). UNH: wait until soil is about 60°F and heavy frost has passed for direct sow.

How deep and how far apart?

About ¼ inch (UNH) or ¼–½ inch (Wisconsin); light inhibits germination (Wisconsin). Thin to about 16 inches (UNH).

Is calendula the same as marigold?

No. Pot/English marigold is Calendula officinalis; garden marigolds are Tagetes species (Wisconsin).

Sources