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Calendula

Calendula officinalis · daisy family

At a glance

Light
Part sun
Frost
Half hardy (estimate)
Days to maturity
50–65 (estimate)
Lifespan
Annual
On this page

Also called pot marigold.

No photo of this plant yet. We add one once we have a picture we can credit.

When do I plant this? › Plan this in your garden ›

The numbers

Mature height
30–61 cm12–24 in
Mature spread
30–61 cm12–24 in
Days to maturity
50–65 (estimate)
Light
Part sun
Feeding
Light feeder (estimate)
Root depth
Shallow (estimate)
Frost tolerance
Half hardy (estimate)
Lifespan
Annual
Habit
Bush
Value to pollinators
High (estimate)

USDA PLANTS profile

Before you sow

What the seed asks for before it will come up.

Germination soil temperature
16 °C61 °F
Days to germinate
10–15 days
The source

extension.unh.edu

How to Grow Calendula (Calendula officinalis) University of New Hampshire Extension

Numbers we’re less sure of

Many of our estimates come from an extension page we’ve read that gets close without pinning the number down. Others are still our own best guess, and on some the sources disagree. Treat them all as a starting point.

Rules that apply to calendula

Do not plant lettuce or its family in ground that held it within 3 years, and know that lettuce drop's fungi live on most other vegetables too. A good hunch

Do not plant lettuce or its family in ground that held it within 3 years, and know that lettuce drop's fungi live on most other vegetables too.

A good hunch

If you skip this, you lose real yield. The planner suggests it.

How it works: Bottom rot (Rhizoctonia solani) and lettuce drop (Sclerotinia sclerotiorum and S. minor) survive in soil as mycelium and sclerotia for years and build where lettuce repeats; a three-year break holds bottom rot down. Drop's fungi infect alliums, brassicas, nightshades, cucurbits and legumes as well, so a lettuce rotation slows them without starving them, and only cereals are safe ground.

Evidence: checked against 4 sources in the research-based literature.

The 4 sources

vegetables.cornell.edu

Do Rotations Matter within Disease Management Programs? Cornell Vegetables
Bottom rot (Rhizoctonia) | 3 years

content.ces.ncsu.edu

Lettuce Drop NC State Extension
Sclerotinia sclerotiorum and S. minor have a wide host range infecting allium (onion, garlic), brassica (cabbage, broccoli), solanaceae (pepper, potato), cucurbits (cucumber, squash), lettuce, and sweetpotato crops

extension.usu.edu

Drop (Sclerotinia Rot) Utah State University Extension
The sclerotia can survive dormant in the soil for extended periods

umass.edu

UMass Vegetable Notes 2024 vol. 36:2
Rhizoctonia survives in the soil, as mycelium or sclerotia
Remedy

Plant lettuce and its family in different ground, or wait until 3 years have passed since this ground last held them. Where drop has shown, the break that counts is one of grains or corn, since most vegetables carry it, and dead plants go in the bin. Keep them out of the compost, because the sclerotia survive it.

Read the full rule › · open in the planner ›

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself. Promising

Cold-hardy annuals can be sown or transplanted before the last spring frost (hardy crops about three weeks before, half-hardy about two weeks before). Tender crops wait for the frost itself.

Promising

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Cold hardiness. Hardy crops tolerate hard frost and half-hardy crops tolerate light frost, so they can occupy the ground weeks before frost-tender crops are allowed in. The offset is measured from the last spring frost.

Evidence: checked against 2 sources in the research-based literature.

The 2 sources

extension.illinois.edu

Time Your Vegetable Plantings by Cold Hardiness University of Illinois Extension
… withstand freezing temperatures and hard frosts without injury

extension.colostate.edu

Vegetable Planting Guide Colorado State Univ. Extension, GardenNotes #720
As early as 2-4 weeks before the date of the average last spring frost

Plus 2 working notes on how the sources were read.

Read the full rule › · open in the planner ›

Frost can form on a night the forecast low is a few degrees above freezing. Promising

Frost can form on a night the forecast low is a few degrees above freezing.

Promising

If you skip this, the planting fails. The planner warns you.

How it works: On a clear, still night leaves lose heat to the open sky, so a leaf can fall to freezing and ice can form in it while the thermometer, a couple of meters up, still reads a few degrees above.

Evidence: checked against 7 sources in the research-based literature.

The 7 sources

www.weather.gov

Frost and Freeze Information NWS Tallahassee
Issued up to 24 hours when temperature is forecast to be between 32° and 36° on nights with calm winds

www.weather.gov

Freeze Watches and Warnings National Weather Service
… temperatures below 28°F for an extended period of time can kill most types of commercial crops and residential plants.

ipm.ucanr.edu

Freezing and Frost UC Statewide IPM Program
Frost occurs when air is warmer than 32°F but plant tissues drop to 32°F or below because plants radiate (lose) heat into the atmosphere, especially during cool, clear nights.

yardandgarden.extension.iastate.edu

Fall Planting of Vegetables Iowa State University Yard and Garden, Aaron Steil and Kim Hilgers
Tender crops will be damaged or destroyed by a light frost

extension.sdstate.edu

Fall Frost Tolerance of Common Vegetables SDSU Extension, Rhoda Burrows
Crops from more-temperate regions can withstand light freezes (28 to 32 degrees Fahrenheit):

extension.umn.edu

A Minnesota guide to garden timing UMN Extension, Robin Trott
A light frost (32°F) can damage tender plants, while a hard frost (28°F or colder) will kill most warm-season crops.

extension.colostate.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
Radiation frosts occur on calm clear nights that lack cloud cover to hold in heat.
Remedy

The evening before, cover the crops at risk with a sheet or frost cloth, never plastic, reaching the ground and loose at the bottom so the soil's warmth can rise under it, and take it off in the morning. A cover helps least in a long, hard freeze.

Read the full rule › · open in the planner ›

A cover buys cool-season crops a week or two at the ends of the season. A good hunch

A cover buys cool-season crops a week or two at the ends of the season.

A good hunch

If you skip this, it still grows, just less well. The planner suggests it.

How it works: Soil warmed by the sun by day is the heat source at night; a covering low to the ground traps that heat around the plants on calm, clear nights, keeping them a few degrees above the open air through the light frosts at each end of the season.

Evidence: checked against 6 sources in the research-based literature.

The 6 sources

yardandgarden.extension.iastate.edu

All About Cold Frames Iowa State University Extension and Outreach, Aaron Steil
The ground and frame of the cold frame are heated by the sun during the day and radiate that heat during the night, keeping the inside warmer. They are used to extend the growing season by two to four weeks in both the fall and the spring, allowing you to start plants outdoors earlier and continue growing them later in the season.

extension.colostate.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
In trials in Fort Collins, Colorado, a plastic cover on a frame typically provides 3°F to over 6°F of frost protection. It works well for cool season crops that are somewhat tolerant of frosty nights and adds two to six weeks or more on both ends of the growing season.

class.ucanr.edu

Frost Protection and Extending the Growing Season CSU Extension GardenNotes #722, Whiting, O'Meara and Wilson
Soil warmed by the sun in the daytime, is the source of heat for frost protection at night. Moist, smooth soil absorbs more heat. To trap heat from the soil around young vegetables at night, place a covering that is low to the ground and spreading. To recharge the heat source for the next night, any covering must allow sunlight to shine through to the soil or must be removed in the daytime.

extension.usu.edu

Extending the Garden Season Utah State University Extension, Beddes, Caron, Hansen and Gunnell
Low = Plant 1–2 weeks before suggested planting date; Medium = 2–4 weeks before suggested planting date; High = 4–8 weeks before average planting date

hort.extension.wisc.edu

Floating Row Cover University of Wisconsin-Madison Extension, Wisconsin Horticulture, Susan Mahr
Depending on the weight of the covering you choose, you can gain between 2 and 8 degrees of frost protection or warm the local environment sufficiently to harvest certain crops a week or two early.

uaex.uada.edu

Row covers for vegetable gardening University of Arkansas System Division of Agriculture, Cooperative Extension Service
Clear plastic is useless in providing frost protection because the radiant energy released from the soil on those frosty nights passes right through the covering and never warms the air around the plants.
Remedy

Sow or set out cool-season crops under the cover that many weeks ahead of the open-ground date, and keep autumn crops covered past the usual last call. Vent on sunny days, keep plastic off the leaves, and close the cover before sunset.

Read the full rule › · open in the planner ›

Hardy crops can go in later, counted back from the freeze they can't stand Promising

Hardy crops can go in later, counted back from the freeze they can't stand

Promising

If you skip this, you lose real yield. The planner warns you.

How it works: A hardy or half-hardy crop's tissue survives the ice of a light freeze down to about 28 °F (-2 °C), so its season ends at the first night that cold, which comes after the first 32 °F frost, and later still where winters are mild.

Evidence: not yet confirmed. It is cited to 8 sources, which a person has yet to read.

What this rests on - 8 pointers

agrilifeextension.tamu.edu

Fall Vegetable Gardening Guide for Texas Texas A&M AgriLife Extension, EHT-056

We summarise this source in our notes rather than quote a line from it.

yardandgarden.extension.iastate.edu

Fall Planting of Vegetables Iowa State University Extension and Outreach
Tender crops will be damaged or destroyed by a light frost, semi-hardy crops can tolerate temperatures in the upper 20s°F, and hardy crops will survive temperatures in the mid to low 20s°F.

extension.sdstate.edu

Fall Frost Tolerance of Common Vegetables SDSU Extension
Crops from more-temperate regions can withstand light freezes (28 to 32 degrees Fahrenheit):

vegetables.ces.ncsu.edu

Frost and Freeze Protection for Vegetable Crops NC State Extension
If water within the plant cell or between the plant cells freeze, this can result in damage to plant tissue.

extension.oregonstate.edu

Plant cold-hardy vegetables now for a spring harvest Oregon State University Extension
Semi-hardy crops tolerate light frost (28–32°F), including beets, carrots, parsnip, lettuce, chard, garden pea (before flowering), Chinese cabbage, endive, radicchio, cauliflower, parsley and celery.

extension.umn.edu

A Minnesota guide to garden timing University of Minnesota Extension
A light frost (32°F) can damage tender plants, while a hard frost (28°F or colder) will kill most warm-season crops.

www.weather.gov

Understanding Cold Weather Alerts National Weather Service
This temperature threshold kills some types of commercial crops and residential plants, while temperatures below 28°F for an extended period of time can kill most types of commercial crops and residential plants.

www.ncei.noaa.gov

Normals Calculation Methodology 2020 NOAA NCEI
Frost-freeze probabilities are the likelihood that a given minimum temperature will be experienced at least once during a month or year.

Plus one working note on how the sources were read.

Remedy

Sow or set out hardy crops up to the date the app gives. After it, choose a faster variety or wait for the spring sowing.

Read the full rule › · open in the planner ›

Another 138 rules depend on your own garden, like crop rotation, frost dates, sun, spacing and soil. See them all.

When do I plant calendula? ›

What grows well with calendula? · Something wrong with your calendula?

More ways Milpa can help

When do I plant? · What grows well together? · Plan my garden · What can I plant now? · Something wrong in the garden? · Keep a garden diary · Heard a tip?

Cite this page

Milpa Gardens. “Calendula (Calendula officinalis).” https://milpa.garden/plants/calendula-officinalis/

A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.

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