Sow calendula outdoors just before your last spring frost, or start seed indoors 6 to 8 weeks before the last frost for earlier flowers (Wisconsin Horticulture). Sow again every few weeks for a steady supply. It is a cool-weather flower: plants may stall in a long, hot summer but usually recover when it cools and keep blooming until the first heavy frost. In mild-winter areas, UF/IFAS grows it in the winter garden.
Calendula (Calendula officinalis), also called pot marigold, is an annual in the daisy family from southern Europe and the eastern Mediterranean (Wisconsin Horticulture). Despite the common name, it is not a true marigold. Those are Tagetes, which want warm soil and frost-free weather; see when to plant marigolds. Calendula is a bushy plant about 1 to 2 feet tall (NC State, UF/IFAS) with orange, yellow and cream daisy flowers, and it is one of the easiest annuals to grow from seed.
Planting dates by last frost
Wisconsin Horticulture says to sow seed outdoors just before the last frost date, or indoors about 6 to 8 weeks before it for earlier bloom. GardenPal turns that into dates for each frost date. The transplant column is our estimate:
| Average last spring frost | Sow seed outdoors | Start indoors | Plant seedlings out (GardenPal estimate) |
|---|---|---|---|
| Mar 1 | Feb 22 – Mar 1 | Jan 4 – Jan 18 | Mar 1 – Mar 8 |
| Mar 15 | Mar 8 – Mar 15 | Jan 18 – Feb 1 | Mar 15 – Mar 22 |
| Apr 1 | Mar 25 – Apr 1 | Feb 4 – Feb 18 | Apr 1 – Apr 8 |
| Apr 15 | Apr 8 – Apr 15 | Feb 18 – Mar 4 | Apr 15 – Apr 22 |
| May 1 | Apr 24 – May 1 | Mar 6 – Mar 20 | May 1 – May 8 |
| May 15 | May 8 – May 15 | Mar 20 – Apr 3 | May 15 – May 22 |
| Jun 1 | May 25 – Jun 1 | Apr 6 – Apr 20 | Jun 1 – Jun 8 |
Successive sowings and the summer slump
Wisconsin Horticulture recommends successive sowings to keep fresh, blooming plants coming through the season. That matters because calendula may languish in prolonged hot weather. The same source says plants typically recover when cooler weather returns and then bloom almost continuously until the first heavy frost. A practical pattern is a spring sowing, another a few weeks later, and a midsummer sowing for fall flowers (GardenPal suggestion). Nigella works the same way, with sowings every few weeks; see when to plant nigella.
Mild-winter areas
UF/IFAS calls calendula a good fit for the winter vegetable garden, adding color next to collards and cabbage. It also notes transplants can be hard to find, so seed is the best bet. Where winters are mild, treat calendula like other cool-season flowers: sow in fall as the weather cools, and expect it to fade as summer heat arrives (GardenPal suggestion, based on the heat note from Wisconsin Horticulture).
Site, soil and care
| Step | What extension sources say |
|---|---|
| Sun | Full sun (Wisconsin Horticulture); full sun or part shade (NC State, UF/IFAS) |
| Soil | Any well-drained soil (Wisconsin Horticulture, UF/IFAS) |
| Spacing | 12 to 18 inches (UF/IFAS) |
| Feeding and water | Flowers best without heavy fertilizer; moderate watering (Wisconsin Horticulture) |
| Pinching | Pinch when several inches tall for bushier plants (Wisconsin Horticulture) |
| Deadheading | Deadhead regularly for more flowers; plants left to seed may self-sow (Wisconsin Horticulture, UF/IFAS) |
Pests and diseases
Wisconsin Horticulture says calendula generally has few problems but may get aphids, powdery mildew and, occasionally, cucumber mosaic virus. NC State lists it as deer and rabbit resistant.
Calendula in the vegetable garden
Calendula is a popular edging for vegetable beds, and Wisconsin Horticulture says its flowers attract pollinators and beneficial insects. Be careful with bigger claims, though. The same source says the companion-planting idea that calendula deters insects from nearby plants has not been verified scientifically. Grow it for flowers and for the insects it feeds; see flowers that attract beneficial insects and companion planting for pest control for what the research does support.
Frequently asked questions
When should I plant calendula?
Sow outdoors just before your last spring frost, or start indoors 6 to 8 weeks before it (Wisconsin Horticulture). Successive sowings keep fresh plants blooming.
Is calendula the same as marigold?
No. Calendula is called pot marigold, but true marigolds are Tagetes (Wisconsin Horticulture). They have different timing: calendula likes cool weather and marigolds want warmth.
How deep should I plant calendula seeds?
About ¼ to ½ inch deep, because light inhibits germination. Seedlings appear in 5 to 15 days (Wisconsin Horticulture).
Why did my calendula stop blooming in summer?
Calendula may languish in prolonged hot weather but usually recovers when it cools (Wisconsin Horticulture). Deadhead and sow again for fall.
Does calendula keep pests away?
Wisconsin Horticulture says the claim that calendula deters insects from nearby plants has not been verified scientifically, though its flowers attract pollinators and beneficial insects.
Will calendula come back every year?
It is an annual, but it may self-sow (Wisconsin Horticulture, UF/IFAS). Deadhead if you don't want volunteers.
Check which vegetables you're edging with calendula, and spot any poor pairings before you plant.
Open itSources
- Virginia Cooperative Extension, "Companion Planting in Gardening" (SPES-620P)
- University of Maryland Extension, "Vegetable Succession and Companion Planting"
- Oregon State University Extension, "Companion Planting"
- Penn State Extension, "Herbs Make Good Plant Partners and Companions"
- University of Minnesota Extension, "Planting the vegetable garden"
- USDA Plant Hardiness Zone Map
- NOAA NCEI U.S. Climate Normals (frost/freeze data)
- University of Wisconsin-Madison Extension, Wisconsin Horticulture, "Calendula, Calendula officinalis"
- NC State Extension Gardener Plant Toolbox, "Calendula officinalis" (pot marigold)
- UF/IFAS Gardening Solutions, "Calendula"
Pairings are summarized in our own words from extension-service guidance. Research support for many companion effects is limited, so treat them as good habits, not guarantees.