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Herbs, Flowers & Specialty CropsCalendula Planting Calendar
Calendula shrugs off light frost and flowers for a long season if you keep cutting. Getting seed in at the right soil temperature is most of the work.
Key points
- Sow calendula once soil reaches about 60 degrees Fahrenheit and heavy frost has passed.
- Cover seed with about a quarter inch of soil and expect germination in ten to fifteen days.
- Thin to roomy spacing so plants branch and flower heavily.
- Pick half-open flowers and cut often for a long season.
When should you sow calendula?
University of New Hampshire Extension says calendula is direct sown outdoors in early spring, once the soil reaches about 60 degrees Fahrenheit and the danger of heavy frost has passed. That wording ties the date to soil and frost, which is the right way to think about it.
Use a soil thermometer to check your garden, and find your average last frost from the National Weather Service or your county extension office. Plants tolerate light frost, so you do not need to wait for the very last frost.
If you want blooms earlier, you can start seed indoors and transplant after frost danger has passed. Seedlings tolerate transplanting well when small, but direct sowing is still the easiest approach.
- Check soil temperature in the morning at planting depth.
- Sow thinly to cut down on thinning.
- Mark rows so seedlings are not mistaken for weeds.
- Watch the forecast for a hard freeze after sowing.
How deep and how thick should you sow?
The same source advises sowing seed thinly and covering it with about a quarter inch of soil. Germination typically takes ten to fifteen days, so keep the seedbed evenly moist while you wait.
Press the soil down firmly after sowing to bring seed into contact with moisture. Mark your rows, since seedlings can be hard to tell from weeds at first.
How far apart should you thin calendula?
Thin seedlings when they are one to two inches tall. The UNH guide gives about sixteen inches between plants and between rows, which is wide for a small plant but lets them branch and flower heavily.
Crowded plants stay damp, flower less and are more prone to mildew. If you want a tighter cut-flower bed, check the spacing on your seed packet and your own experience, and use a bit more airflow between rows.
What site and soil does calendula need?
Calendula grows best in full sun with evenly moist, well-drained soil. It is not fussy, but it does poorly in soggy ground. Use a soil test and local recommendations before adding fertilizer, since too much encourages leaves instead of flowers and nutrient management rules vary by state.
In hot summers, plants may slow or stall. A bit of afternoon shade and consistent watering help, and many growers sow again in late summer for a fall flush.
Water at the base and keep the soil evenly moist during dry spells. Too much water leads to rot, while too little slows blooming.
How do you succession plant and cut calendula?
Sow every few weeks in cool weather for a steady supply, and again as temperatures ease in late summer. In mild regions, fall-sown plants may overwinter and bloom early. The UNH source notes that picking flowers when they are half open helps them last longer in the vase.
Cut regularly and remove spent blooms to keep plants producing. Leave a few flowers to set seed if you want volunteers, since calendula self-sows.
Sort cut flowers by stem length, and strip leaves below the water line to keep vase water clean. Cut stems in the cool of the morning.
- Cut flowers when they are half open.
- Remove spent blooms to extend flowering.
- Leave a few flowers to set seed for volunteers.
- Sow again in late summer for fall blooms.
What problems should you watch for?
Powdery mildew, aphids and leaf spots are the common issues, particularly in humid weather or crowded beds. Good spacing, morning watering and removal of damaged leaves are the first line of defense.
If you consider any pesticide, the label is the law, pre-harvest intervals apply and applicator licensing varies by state. Calendula blooms attract pollinators, so protect them and ask your extension office for current advice.
- Space plants for airflow.
- Water at the base in the morning.
- Remove damaged leaves promptly.
- Ask extension to identify problems before treating.
What does a calendula calendar look like?
Write down your average last frost and the date the soil first reaches about 60 degrees in your garden. Sow then, repeat every few weeks while it is cool, and add a late summer sowing. Note when plants peaked and when heat slowed them.
After a season or two you will know the pattern for your site, which is more useful than any general chart.
Keep a simple notebook of sowing dates, bloom dates and any problems, and compare year to year.
Timing at a glance
| Item | Window | Caveat |
|---|---|---|
| Calendula direct sowing, University of New Hampshire Extension | Early spring, once soil reaches about 60 degrees Fahrenheit and heavy frost has passed | Source guidance for New Hampshire; local frost dates differ, so check yours. |
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.