Ornamental · Asteraceae
Calendula
Calendula officinalis
Give it full sun and lean soil, and pot marigold blooms from spring right up to frost.
Full sun
Every 3–7 days
39–75°F · 4–24°C
45–65 days
Overview
Calendula, or pot marigold, is a cool-season annual in the daisy family that earns its place with sheer willingness. Sow it once and it flowers from spring into fall, then drops seed and comes back on its own the next year. The bright yellow and orange heads are edible, which is why cooks have long scattered the petals over salads and used them to color food.
It asks for almost nothing. Average, well-drained soil and a spot in full sun are enough, and it actually blooms better when you hold back on the fertilizer. The plant runs out of steam in real summer heat, but a hard cutback often brings a fresh flush of flowers once the weather cools in fall.
This is a good choice for a beginner or a busy gardener. Deadhead it now and then, keep the foliage dry to fend off mildew, and calendula carries the front of a bed or a kitchen border with very little fuss.
Care
The short version: full sun, average well-drained soil, and a light hand with fertilizer. Keep it evenly watered at the base, deadhead the spent flowers, and it blooms cool-season spring through fall.
Light
Calendula flowers best in full sun but will take partial shade, especially where summers turn hot. The more sun it gets, the more bloom you'll see, so give it the brightest spot you have.
Water
Keep the soil evenly moist with regular watering, and make sure it drains well so the roots never sit wet. Water at the base rather than over the top, since wet leaves invite powdery mildew. Its overall water needs are only medium.
Soil
Average, well-drained soil is all it wants, and it shrugs off clay, loam, sand, or rich ground alike. A pH anywhere from 5.5 to 7.0 suits it fine. Good drainage matters more than fertility here.
Temperature
This is a cool-weather plant, happiest from about 39°F to 75°F (4°C to 24°C). It can stall and look ragged in midsummer heat, then bounce back as the weather cools in fall.
Humidity
Ordinary outdoor humidity is no trouble, so there's no target to hit. Air movement matters more than the number, since crowded, damp plants are the ones that pick up mildew.
Feeding
Feed lightly, if at all, during the growing season. Calendula blooms best on lean soil, and a heavy feed just grows leaves at the cost of flowers.
Pruning
Deadhead the spent blooms as they fade to keep new ones coming and to curb self-seeding. If the plant flags in summer heat, cut it back hard and it often reblooms once fall arrives.
Size & spacing
Plants reach about 12 to 24 inches (30 to 61 cm) tall and spread to a similar width. Give each one that much room so air moves freely and mildew has less of a foothold.
When to plant
Calendula is a cool-season annual that does its best work in the mild weather at either end of summer. Start seed indoors in late winter or sow it straight into the ground around the last frost, and the flowers carry on from spring until a hard frost finally stops them.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: About 6 to 8 weeks before the last spring frost
- Plant: Direct sow or transplant just before to around the last spring frost; a cool-season annual best in spring and fall
- Harvest: Blooms spring through summer, continuing almost nonstop until first heavy frost in cool climates
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Calendula is tough, and most of its problems show up on the leaves or new growth. Catch them early and a quick fix usually settles things. Match what you see below, then act before it spreads.
Mottled, distorted leaves on a plant that won't thrive
Yellow-green mottling and twisted leaves that no amount of water or feed will fix point to cucumber mosaic virus, which aphids carry from plant to plant. There's no cure, so dig out and destroy any plant that shows it before it spreads. Keep the aphids in check and wash your hands between plants to slow the virus down.
Fix:
- Remove and destroy infected plants to limit spread
- Control aphid vectors
- Avoid handling healthy plants after touching infected ones
White powdery coating on leaves and stems
This is powdery mildew, a fungus that takes hold when plants sit crowded in still, humid air. Thin the planting so air can move through, water at the base to keep the leaves dry, and pull off any leaf that's badly coated. Full sun and a bit of room between plants keep it from coming back.
Fix:
- Improve air circulation by thinning and spacing plants
- Water at the base to keep foliage dry
- Remove and discard severely affected leaves
Sticky clusters of small insects on buds and new shoots
Those soft green or black specks are aphids, drawn to the tenderest new growth and the flower buds. A hard jet of water knocks most of them off, and insecticidal soap handles a heavy run. Skip the high-nitrogen feed that pushes the soft, sappy growth they love, and let lady beetles do their share.
Fix:
- Spray plants with a strong stream of water to dislodge aphids
- Apply insecticidal soap if populations are high
- Encourage beneficial insects such as lady beetles
Ragged holes chewed through leaves and flowers
Slugs and snails feed after dark and hit young plants hardest, leaving torn holes and a telltale slime trail behind them. Go out at dusk with a flashlight and pick them off, and clear away the damp debris they hide under. Iron-phosphate baits or simple traps help when the damage keeps mounting.
Fix:
- Hand-pick slugs and snails in the evening
- Remove garden debris that provides shelter
- Use traps or iron-phosphate baits if damage is heavy
Toxicity
Good news on this one. The ASPCA lists pot marigold as non-toxic to cats, dogs, and horses, and the petals are edible for people too. A grazing pet or a curious child is in no danger here, so you can plant it anywhere in the garden.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists pot marigold as non-toxic to cats, so a nibble won't do any harm.
Dogs None
Dogs are in the clear here too. This is the garden pot marigold, not the bedding type, and the ASPCA rates it safe.
Horses Safe
No toxic compounds are known in calendula, so grazing horses have nothing to fear from it.
Rabbits Safe
Rabbits can browse the leaves and petals without trouble, and the flowers are often grown as a safe forage.
Livestock Safe
Cattle, goats, and sheep tolerate calendula well, with no reports of poisoning.
Birds Safe
Backyard birds can peck at the seed heads and petals safely.
People Safe
The petals are edible and turn up in salads and as a saffron-style coloring, so people have nothing to watch out for.
Varieties
Calendula comes in a handful of flower forms and colors worth knowing before you sow. These are the ones you'll run into most.
Double-flowered types
These carry full, many-petaled heads in shades of yellow to deep orange instead of the open single daisy.
Single-flowered types
These bear open, daisy-like blooms with one ring of ray petals circling a flat central disk.
Yellow to orange color forms
Their flowers run from bright yellow to deep orange, and the edible petals make a handy garnish or natural coloring.
How to propagate
Calendula spreads from seed and little else, but it does that with almost no help, sprouting fast and even reseeding itself for next year.
SeedEasy
Start indoors about 6 to 8 weeks before the last frost, or direct sow outdoors around the last spring frost · Germinates in about 5 to 15 days; first blooms in roughly 45 to 65 days from seed
Calendula is one of the easiest flowers to grow from seed. Start it indoors 6 to 8 weeks before your last frost or sow it straight into the ground around frost, setting the seed about 1/4 to 1/2 inch deep. Sprouts come up in 5 to 15 days and the first flowers open within 45 to 65 days. Left alone, the plant drops seed and reseeds itself, though never enough to take over.
Myths
Calendula is just another name for the common bedding marigold and is mildly toxic to pets.
Pot marigold is Calendula officinalis, a different genus from the Tagetes bedding marigolds people often confuse it with. The ASPCA lists it as non-toxic to dogs and cats, so the toxicity worry doesn't apply here.
Calendula needs rich soil and heavy feeding to bloom well.
It does fine in average, well-drained ground and asks for very little. Heavy feeding actually works against the flowers, pushing leafy growth at the expense of blooms, so go light on the fertilizer.