How to Grow Coleus Seeds

Grow Guide #2877
Family: Lamiaceae
Binomial name: Plectranthus scutellarioides
Life Cycle: Annual

This 'How to Grow' guide details everything a home gardener needs to know to plant, grow and care for Coleus (Plectranthus scutellarioides).

When to Sow Coleus Seeds

Use the table below to identify the best time of year to sow coleus seeds in your climate.



Coleus plants are best grown in full or part shade. Choose a location that will receive a maximum of 3 hours of full sun each day.

Coleus is also suitable to grow indoors and in terrariums.

Indoors and in warm climates, Coleus plants are short-lived perennials, meaning they usually live for between two and five years. Choose a permanent position where plants can grow undisturbed by regular digging or disturbance.

Coleus plants need a well drained soil enriched with plenty of organic matter. Prepare soil by weeding it thoroughly, digging it over to loosen it and adding aged animal manure or compost. Keep the area free of weeds until planting. Learn more about preparing soil for planting here.

Coleus plants can be grown in containers. If possible choose a variety that’s recommended for container growing. Use a good quality potting mix and make sure your container is large enough for mature plants; a minimum of 20 litres is recommended for coleus. During the growing season, keep in mind that container grown plants may need additional fertiliser to encourage healthy growth.

How to Sow Coleus Seeds

Coleus seeds do not require any treatment (eg soaking, stratification) before sowing.

Coleus seeds can be sown directly into the garden OR seedlings can be raised in trays or other containers and transplanted to the garden once established.

Sow Direct

  1. Sow seeds directly in the garden 5mm deep and 50cm apart.
  2. Keep soil moist but never wet or dry.
  3. Seeds should germinate in around 10-20 at a soil temperature of 18-24°C.
  4. Young seedlings will need protection from pests, pets and weather until they are established.

Raise Seedlings

  1. Fill trays, punnets or jiffy pots with a good quality seed-raising mix, or use soil starter pellets.
  2. Sow seeds 5mm deep.
  3. Keep soil moist but never wet or dry.
  4. Seeds should germinate in around 10-20 at a soil temperature of 18-24°C.
  5. Transplant seedlings to the garden once they have their first true leaves and are large enough to handle (usually 5-10cm tall).
  6. Plant out, spacing plants 50cm apart.

Coleus is a tender crop that’s sensitive to frost. Do not transplant seedlings or sow seeds outside until all danger of frost has passed.

Tip: Coleus seeds can also be sown in the less formal ‘scatter seed’ method. Simply roughen the soil, scatter seeds evenly over the surface, then smooth the soil over lightly to cover the seeds.

Tip: Coleus seeds are quite small. Handle them carefully to avoid them blowing away or being washed away. Mix seeds with sand or fine potting mix prior to sowing or use a seed dispenser, damp toothpick or tweezers to help space them evenly. Press lightly into the surface after sowing so that the seeds make good contact with the soil. Take extra care to make sure seeds and seedlings don’t dry out. Read more about sowing small seeds here.

Optional: In cool climates coleus seeds can be sown indoors 6 weeks before the last expected frost. Grow them in a warm position with plenty of natural light.

How to Grow Coleus

Coleus plants need regular watering during the growing season. Do not let soil dry out; keep soil evenly moist but not waterlogged. Water deeply in the early morning or late afternoon. Avoid watering the leaves of plants to avoid fungal diseases. Learn more about watering here.

If soil was well prepared no extra fertiliser should be necessary. In poor soil or to give your plants an extra boost, application of a balanced fertiliser or one formulated for fruit and vegetables can be beneficial:

  • Apply slow release fertiliser at the recommended rate when transplanting or when seedlings are 5-10cm tall.
  • Apply liquid fertiliser at the recommended rate and frequency while plants are fruiting or flowering.

Pinch out the growing tips of coleus plants to encourage denser growth with stronger stems. Using sharp secateurs or snips remove the top set of leaves, cutting just above a set of lower leaves. The small flowers can also be pinched off to promote leaf growth. The small flowers can also be pinched off to promote leaf growth.

Coleus should reach maturity in approximately 110 days.

Common Problems when Growing Coleus

Like all plants, coleus is susceptible to some pests, diseases and other problems. Below is a list of the most common problems gardeners encounter when growing coleus plants:

  • Downy Mildew
    Downy mildew is a fungal disease that causes yellow to grey-brown patches on leaves, especially the undersides. Water plants at soil level (not on the leaves), remove and destroy affected leaves and do not overcrowd plants to ensure adequate air flow. If problems persist, spray with a homemade milk spray or fungicide.
  • Mealybugs
    Mealybugs (Pseudococcidae sp.) are small (3-6mm long) sap-sucking insects with white, pink or gray bodies covered in a mealy coating that looks like cotton wool. They can cause leaves to wilt and also excrete honeydew which can attract ants and other insect pests. To manage mealybugs, remove them by wiping leaves, apply a soap or alcohol spray, or encourage predatory insects to your garden. Read more about mealybugs here.
  • Scale
    Scale are a diverse group of sap-sucking insects that congregate on the new shoots or the undersides of leaves. They may be hard or soft bodied and brown, orange, grey or white. Scale can damage leaves and also excrete honeydew which can attract ants and other insect pests. To manage scale, brush or hose them off leaves, apply a soap spray, or prune off heavily infested leaves and shoots. Read more about scale here.
  • Whitefly
    Whitefly is a sap-sucking insect related to aphids. They are often found in large numbers on the underside of leaves and will swarm in clouds when disturbed. Plants may have yellowing leaves or may wilt, and growth will be slowed. Whitefly can be removed with a garden hose or sprayed with soap spray. Badly affected plants should be destroyed. Attracting beneficial insects that will prey on whitefly can be beneficial. Read more about managing whitefly here.

Browse Coleus Seeds

Coleus- Colocha Sunset

Coleus- Colocha Sunset

Packet 50 seeds


Coleus- Mixed Rainbow

Coleus- Mixed Rainbow

Packet 275 seeds