How to grow Celosia

Celosia argentea · cockscomb, plumed cockscomb

Celosia (Celosia argentea) — a tropical annual of the amaranth family grown for its velvety flower heads — feathery plumes, crested "cockscombs" folded like coral, or slim spikes — in red, orange, yellow, pink, purple and cream. It thrives in heat and humidity and flowers from summer to the first frost; the heads last up to two weeks in a vase and dry well. Young leaves are edible, and NC State lists it as non-toxic to cats, dogs and horses.

Checked against sources: October 3, 2026

Quick facts

Type	Flower
Family	Amaranthaceae
Light	Full sun
Soil pH	6–7
Frost	does not tolerate frost
Soil for sowing	from 16 °C
Germination	10 days
Seedlings ready	35 days
Where it grows	Greenhouse, Open ground, At home

When to plant

Sow for seedlings about 6 weeks before planting out.

Plant out in open ground about a week after your last spring frost, once the soil is warm.

In an unheated greenhouse everything moves about three weeks earlier.

Frost dates · When to plant

Care

Greenhouse

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	17…20 °C	—
Growth	every 4 days	20…40 °C	balanced (NPK), at the start of the stage; balanced (NPK), 49 days into the stage
Flowering	every 4 days	20…40 °C	—

Open ground

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	17…20 °C	—
Growth	every 4 days	20…40 °C	balanced (NPK), at the start of the stage; balanced (NPK), 49 days into the stage
Flowering	every 4 days	20…40 °C	—

At home

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	17…20 °C	—
Growth	every 3 days	20…40 °C	balanced (NPK), at the start of the stage; balanced (NPK), 49 days into the stage
Flowering	every 3 days	20…40 °C	—

Growing notes

Light

Full sun — strong light keeps the plants compact and the colours bright.

Soil

Fertile, moist, well-drained soil rich in organic matter, pH 6.0–7.0. It also copes with dry, porous soil, but wet, heavy ground causes root rot.

Care

Sow 6–8 weeks before planting out at 22–27 °C, pressing the tiny seed into the surface or covering it only very lightly, and water from below; seedlings appear in 8–14 days. Grow them at 17–20 °C — cold and short days make them flower too early. Any frost kills celosia, so plant out only when the weather is warm, or sow directly once it stays above 16 °C. Space plants 15 cm apart for one big head each or 23–30 cm apart for many branching stems, and pinch the tip at 15–20 cm tall for more stems. Water deeply about twice a week, more often in a heat wave, at the base of the plant, and feed at planting and again 6–8 weeks later if growth slows. Stake tall varieties. Crowding, rain and high humidity rot the flower heads; aphids, thrips, slugs, powdery mildew and leaf blight are the usual troubles, and spider mites indoors.

Pests and diseases of Celosia

Two-spotted spider mite

Sources

Figures checked against these sources.