How to Grow Celosia
Celosia argentea
Celosia is a tender annual that thrives in heat and full sun. Sow indoors 6–8 weeks before the last frost date, using bottom heat (20–25°C) for reliable germination. Keep seedlings warm at all times — cold or root-bound conditions trigger premature flowering that stunts the plant. Plant out only after all frost risk has passed and nights are above 15°C. Choose fertile, well-drained soil and a sheltered sunny spot. Deadhead regularly to keep blooms coming, or cut stems for drying when fully coloured — celosia holds its vivid colour exceptionally well as a dried flower.
When to Start
Start seeds indoors 6 weeks before your last frost date. Transplant outdoors once night temperatures stay above 12°C and soil has warmed to at least 15°C.
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Growth Stages
Approximate days from start
Care Essentials
- Feed with a balanced liquid fertiliser every two weeks once plants are established in their final position. Avoid high-nitrogen feeds which promote leafy growth at the expense of flowers.
- Celosia covers two distinct forms — plumosa (feathery plumes) and cristata (brain-like cockscomb). Both are tender annuals that demand warmth. Do not let seedlings get cold or root-bound, as this triggers premature flowering before plants are large enough to perform well.
Growing Conditions
- Min. soil temperature
- 15°C+
- Germination temperature
- 20–25°C
Pet Safety
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
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Spacing & Planting
| Plant spacing | 20 cm |
| Row spacing | 30 cm |
| Sow depth | 0 cm |
| Mature height | 40 cm |
| Mature spread | 25 cm |
Covers both plumosa (feathery plumes) and cristata (cockscomb) types. Plant out only after all frost risk has passed. Closer spacing can increase humidity — ensure good airflow.
Pests & Diseases
Pest Aphids
Identification: Clusters of small soft-bodied insects on shoot tips and flower buds, causing distorted growth and sticky honeydew deposits
- Blast off with a strong jet of water
- Spray with fatty acid-based insecticide
- Encourage ladybirds, lacewings and hoverflies
- Spray with a contact insecticide containing deltamethrin or lambda-cyhalothrin
Pest Spider Mites
Identification: Fine webbing on leaves and stems, with tiny pale speckling on leaf surfaces; worst in hot, dry conditions
- Increase humidity around plants by misting
- Spray with insecticidal soap or neem oil
- Remove heavily infested leaves
- Apply a miticide labelled for ornamental plants
Disease Stem Rot
Symptoms: Soft, discoloured stem base, wilting despite moist soil, plant collapse
Treatment: Remove and destroy affected plants immediately. Improve drainage and avoid overwatering
Prevention: Ensure well-drained soil, avoid waterlogging, and do not plant out in cold wet conditions
Disease Leaf Spot
Symptoms: Brown or tan spots with darker borders on leaves, sometimes with yellowing around the spots
Treatment: Remove affected leaves. Improve airflow around plants. Apply a copper-based fungicide if severe
Prevention: Space plants well, avoid overhead watering, and remove plant debris at the end of the season
Disease Damping Off
Symptoms: Seedlings collapse at soil level with a pinched, water-soaked stem base
Treatment: Remove affected seedlings immediately. Improve ventilation and reduce watering
Prevention: Use fresh sterile compost, avoid overwatering, ensure good airflow around seedlings, and do not sow too densely
Growing Conditions
| Min. soil temperature | 15°C |
| Germination temperature | 20–25°C |
| Base growth temperature | 12°C |
| Min. daylength to start | 12h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Celosia?
- Plant Celosia 20cm apart with 30cm between rows.
- When does Celosia flower?
- Celosia typically flowers approximately 65 days after transplanting.
- Is Celosia frost hardy?
- Celosia is classified as Tender.
