How to plant and grow coleus
Coleus enjoys warm conditions – it does not do well in cold climates or during winter in cool-temperate to temperate regions where night-time temperatures can be very low. They are grown as outdoor plants in warm temperate to tropical areas and as greenhouse plants elsewhere.
Growing coleus in the garden
Coleus prefers a rich, loamy soil enhanced by the addition of weathered animal manure and compost.
Prepare the soil well before planting and add a six month controlled release fertilizer to give the plants a good start.
Plant out seedlings in spring and keep them well watered. Coleus does not tolerate drought.
Make sure excess water can drain freely, otherwise your plant may develop root rot.
As the plant develops, pinch off the growing tips to encourage branching and compact growth.
Growing coleus in pots
Choose a pot large enough to hold a well-developed plant.
Always use a good quality potting mix – a terracotta and tub mix containing a 3-6 month controlled release fertilizer, wetting agent and water retaining crystals is ideal.
As the plant grows, pinch off the shoot tips to allow side shoots to develop.
Coleus does not tolerate drought, so if the weather is hot and there is little rain, water your plant regularly to keep the soil moist. Make sure that excess water can drain freely, otherwise the plants may develop root rot.
For a coleus in a pot, keep the potting soil moist but not wet and allow excess water to drain freely – don’t leave the pot in a saucer of water for more than 30 minutes.
Fertilize Coleus in your garden
Use a water-soluble or liquid plant food every three to four weeks to keep plants healthy and growing strong.
Coleus Pests and Diseases
Coleus is susceptible to downy mildew, which can cause leaves to develop a brown tint and also curl and twist. An all-purpose garden fungicide, applied according to label directions, can help get rid of this. Good air circulation around plants is also important in controlling powdery mildew. If plants are close together, you may need to remove some to improve air movement.
In some areas, a thrips-borne viral disease can also affect plants. Known as necrotic spot virus, it manifests as brown or yellow spots on leaves, discoloration of stems, and browning of leaf veins. There is no cure – infected plants should be removed and placed in a container to prevent spread by thrips to healthy plants.
How to multiply Coleus
Coleus can be propagated by taking cuttings from established plants or by sowing seeds of selected cultivars (seed packets are available).
Growing Coleus from cuttings
To make a cutting, take a piece of stem about 15 cm long with a growing tip at the end.
Cut just below a pair of leaves, removing all but the top leaves and the shoot at the top.
Place the cutting in a glass of water where it will quickly root, or place in a small pot of propagation mix.