How to Grow Coleus
'Improved Rainbow Mix' from Seed
A plant grown entirely for its leaves, in crimson, lime, chocolate, gold and near-black. Every seedling turns out different, and it thrives in shade.
Coleus is grown for its foliage rather than its flowers. The leaves come in crimson, lime, chocolate, gold and near-black, often with three or four colours in a single leaf, and every seedling from a packet looks different. Growing a tray of them is a small experiment.
Unusually for something so colourful, it prefers light shade to full sun, which scorches the leaves and bleaches the colour. That makes it ideal for shady patios, pots by the door and windowsills. Bring it indoors before the frost and it can live on as a houseplant for years.
Quick Facts at a Glance
Plant Type
Tender perennial, grown as annual
Sowing Time
Feb to Apr, under cover
Best Colour
July to September
Position
Light shade, sheltered
Grown For
Foliage
Difficulty
2 out of 5, easy
Understanding the Plant
Coleus, sold as Coleus blumei, is a tender perennial from tropical Asia, grown in the UK as a half-hardy annual or a houseplant. It has square stems, like the mint family it belongs to, and it grows quickly in warmth.
It eventually produces spikes of small blue flowers. These are not showy, and once the plant starts flowering it puts less energy into its leaves, which lose their colour. For the best foliage, pinch the flower spikes out as soon as they appear.
Pinch tips and flowers
Pinch out the growing tips when plants are about 10 to 15cm tall, and keep pinching flower spikes through the season. You will get bushy, compact plants packed with coloured leaves rather than tall, leggy stems.
When & How to Sow
Coleus seed is very fine and needs light and warmth to germinate. Sow indoors from February to April.
Choose your favourites
Colours start to show within a few weeks. Sow a few more than you need and keep the seedlings with the leaf patterns you like best.
Surface sow in warmth. Sprinkle seed over damp seed compost without covering. Keep at 20 to 24°C under a clear lid in good light. Seedlings appear in one to three weeks.
Prick out and pinch. Move seedlings into small pots once they have true leaves. Pinch out the tips at 10 to 15cm to encourage branching.
Plant out when warm. Harden off and plant out or move pots outside from late May or June, once nights are reliably mild, into light shade.
Growing On Tips
Light shade
Bright shade gives the richest colour. Strong midday sun scorches and bleaches the leaves.
Remove flower spikes
Pinch out flower spikes as they form to keep the leaf colour strong.
Keep moist
Water regularly, especially in pots. Coleus wilts quickly when dry but recovers when watered.
Great in pots
Use it in containers on shady patios, by doors or as a windowsill plant.
Overwinter indoors
Bring plants indoors before the first frost and keep on a bright windowsill as houseplants.
Easy cuttings
Tip cuttings root readily in a glass of water, so you can keep favourite colours going.
Common Problems & How to Fix Them
| Problem | Likely Cause | What to Do |
|---|---|---|
| Leaves faded or scorched | Too much direct sun | Move plants into light shade. |
| Tall, leggy plants | Not pinched, or too little light | Pinch growing tips regularly and give bright, indirect light. |
| Colour dulls in late summer | Plant flowering | Remove flower spikes as soon as they appear. |
| Plants collapse in autumn | Cold nights | Bring plants indoors before temperatures drop close to freezing. |
| Seed not germinating | Covered or too cold | Surface sow and keep at 20 to 24°C. |
When to Expect the Best Colour
Plants sown in early spring are colourful from the start and at their fullest from July to September outdoors. Indoors, the colour carries on through winter.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 🌱 Sow indoors | ||||||||||||
| 🪴 Plant out | ||||||||||||
| 🌿 Best colour |
Plant Specifications
Painted leaves for shady corners
Sow indoors in spring, pinch the tips and flowers, and give it light shade. You will have a rainbow of foliage all summer and houseplants for winter.
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