Coleus: Growing and Caring for It Indoors

Botany

Coleus is a herbaceous perennial plant belonging to the botanical family Lamiaceae, just like nettles, sage, and lavender, a large family that includes many aromatic and ornamental plants. Its genus name “Coleus” comes from the Greek “koleos”, meaning “sheath” or “case”, referring to the way its stamens are partially fused.

In French, this plant is commonly called “coléus”, but it is sometimes referred to by the nicknames “coliole”, “gypsy plant”, “house nettle”, or “painted nettle”, due to the resemblance of its foliage to that of nettles. In the wild, coleus grows mainly in the tropical undergrowth of Southeast Asia and Africa, where it thrives in dappled light and rich, moist soil.

Although perennial in tropical climates, it is grown as an annual outdoors in temperate climates, as it does not survive frost. Its sensitivity to low temperatures makes it an excellent conservatory plant, where it enjoys a bright and temperate atmosphere throughout the year. Indoors, it is a highly prized ornamental plant for its vibrant foliage.

Formerly classified in the genus Coleus, coleus now belongs to the genus Solenostemon, which includes more than 150 species, as well as a large number of cultivars and hybrids. The most common varieties in garden centres are derived from Solenostemon scutellarioides (syn. Coleus blumei). These cultivars, often organised into series based on their colours, are distinguished by particularly ornamental foliage, ranging from soft green to deep purple, sometimes enhanced with shades of pink, yellow, or orange, in solid, bicolour, or even tricolour patterns, offering an almost limitless choice to suit both outdoor annual beds and indoor cultivation.

There are many varieties of Coleus, offering vibrant and luminous foliage colours

Fast-growing, coleus forms beautiful bushy clumps, compact, dense, and well-branched. Its habit is upright and slightly pyramidal, with stems that naturally branch out. Depending on the variety, it reaches 30 to 50 cm in height and spread in a single season. Although its lifespan indoors may sometimes be limited to a few years, it can easily be renewed through cuttings, allowing it to be kept indefinitely. Its main appeal lies in its foliage, which is far more ornamental than its flowers.

Coleus is distinguished by its oval or triangular leaves, generally measuring between 5 and 15 cm in length and 3 to 10 cm in width, although these dimensions may vary depending on the variety. Their finely serrated edges give them a slightly scalloped appearance, more or less pronounced depending on the cultivar. Their serrated edges resemble those of nettles or mint, hence its nickname “house nettle”. The leaf surface is often velvety, covered with a fine down. The texture can be more or less puckered, with some varieties showing prominent veins that give the leaf a particular relief. Their opposite arrangement on square stems is a typical characteristic of the Lamiaceae family. Each pair of leaves grows directly opposite the previous one, forming a regular and balanced arrangement. The stems, although flexible and slightly brittle, provide good support for the leaves and contribute to the plant’s bushy appearance. In some varieties, they may also display purple or reddish hues.

The incredible chromatic diversity of the foliage is one of the main attractions of coleus. The palette ranges from absinthe green to acid yellow, from rust to deep purplish-red, as seen in the coleus ‘Palisandra’. Some varieties develop intense shades of Indian pink, while others display a more discreet cream white. Depending on the cultivar, the foliage can be solid, bicolour, or tricolour, with varied patterns such as contrasting veins, marbling, or differentiated edges, or with subtle gradients.

The flowering, although discreet, produces small clusters of blue or purple flowers that appear in summer, but they are often removed to concentrate the plant’s energy on the foliage. Fruiting is anecdotal in ornamental cultivation, as coleus is primarily grown for its foliage. However, if the flowering is left in place, it can give way to small black seeds at the end of the cycle. These seeds can be harvested and saved for home sowing, although the new plants obtained may show variations in colours and patterns compared to the parent plant, due to the genetic variability of cultivated hybrids.

Beyond its ornamental interest, coleus has also been used in certain medicinal traditions, particularly in Asia and Africa, where its extracts were used to treat various inflammatory and digestive disorders. A particular species, Coleus forskohlii (now classified in the genus Plectranthus), is known to contain forskolin, an active compound studied for its effects on metabolism and cardiovascular health. This molecule has attracted the interest of researchers due to its potential role in dilating blood vessels and stimulating certain enzymes involved in cellular regulation.

Coleus amboinicus

Main species and varieties

Coleus plants from the species Solenostemon scutellarioides are available in different seed series, such as the Wizard® series, and are also offered as plug plants.

Our Favourite Varieties

Solenostemon Kong Mix

A cultivar distinguished by its XXL foliage! It offers a dance of green, black, and red hues.

• Flowering time July to October
• Height at maturity 45 cm

See the product sheet

Coleus Pinto Mix seeds

A sensational mix of unrestrained colours!

• Flowering time July to November
• Height at maturity 50 cm

See the product sheet

Coleus Vulcan

A new variety with particularly original foliage, both in its finely serrated shape and its colour.

• Flowering time November
• Height at maturity 60 cm

See the product sheet

Coleus Rainbow Mix Seeds

One of the most popular varieties of all!

• Flowering time July to November
• Height at maturity 50 cm

See the product sheet

Solenostemon Dragon Sunset & Volcano Mixed

A stunning, slightly velvety foliage with multiple colours and fringed, curly edges.

• Flowering time July
• Height at maturity 50 cm

See the product sheet

How to Grow Coleus Indoors?

Where to place coleus?

Coleus should be placed in a bright environment, but without direct sunlight, which could scorch their delicate foliage. Bright indirect light or a few hours of gentle morning or late afternoon sun suits them perfectly. They prefer a stable ambient temperature, between 18 and 25 °C, and dislike cold drafts as well as sudden temperature changes. Indoors, they thrive on a bright windowsill, a well-lit shelf, or even in a temperate conservatory, where they can fully flourish.

Place the Coleus in a bright spot, ideally near a window

When to plant coleus in a pot?

Coleus can be planted or repotted throughout the year, but it is best to do so in spring or early summer, when the light is more intense and the plant enters its active growth phase.

Which pot to choose?

Coleus has a shallow root system but appreciates a container with enough space to grow. A 15 to 20 cm diameter pot made of terracotta or plastic is usually sufficient. Ensure it has drainage holes, as coleus cannot tolerate waterlogging.

What substrate to use?

A mix of potting soil and well-decomposed compost provides a rich substrate, promoting growth and foliage colour. Here is an ideal mix to ensure a good balance between water retention and drainage, avoiding the risk of root rot:

• 50 to 60% universal potting soil or houseplant compost, serving as a nutritious base and retaining the moisture needed for coleus development.
• 20 to 30% perlite, coarse sand, or vermiculite, aerating the substrate and improving drainage, reducing the risk of root suffocation.
• 10 to 20% well-decomposed compost, providing essential nutrients to stimulate growth and strengthen the plant’s resilience.
• A layer of clay pebbles or gravel placed at the bottom of the pot to facilitate water drainage and prevent stagnation, which could lead to root diseases.

How to plant coleus in a pot?

For optimal growth, it is recommended to plant only one plant per 15 cm diameter pot. If coleus is grown alongside other plants in a planter, ensure a spacing of 15 to 20 cm between each plant to avoid competition and promote good air circulation.

1. Spread a layer of gravel or clay pebbles at the bottom of the pot to ensure good drainage and prevent water stagnation.
2. Fill with the substrate.
3. Place the coleus in the pot, ensuring the base of the stem is level with the substrate.
4. Top up with substrate and lightly firm around the roots.
5. Water moderately: an initial watering helps thoroughly moisten the substrate and encourages root establishment.
6. Place the pot in a bright spot, but avoid overly intense direct sunlight.

Coleus blumei ‘Velvet’

How to sow coleus seeds?

Our coleus are available as plug plants, but we also offer a lovely collection of coleus seeds to sow in late winter or spring. Here are our tips for successful coleus seed sowing:

1. Fill a pot with well-draining potting soil.
2. Scatter the seeds on the surface of the soil without covering them, as they need light to germinate.
3. Lightly moisten the substrate.
4. Maintain a temperature of 20 to 22 °C and ensure the substrate stays moist until germination, which occurs in 10 to 15 days.
5. Once the seedlings appear, thin them out to give each plant space and encourage their growth.

On the left, a small coleus seedling from sowing (the foliage colour is already visible!), and on the right, coleus repotted into individual pots.

How to Care for Potted Coleus? Coleus is a vibrant and versatile plant that adds a splash of colour to any garden or indoor space. With its striking foliage in shades of green, red, pink, and purple, it's no wonder this plant is a favourite among gardeners. If you're growing coleus in pots, here are some essential tips to keep it thriving. ### 1. **Choosing the Right Pot** Select a pot with adequate drainage holes to prevent waterlogging. Coleus prefers well-draining soil, so opt for a high-quality potting mix enriched with organic matter. ### 2. **Light Requirements** Coleus thrives in bright, indirect light. While it can tolerate some direct sunlight, too much can scorch the leaves. If growing indoors, place it near a window with filtered light. ### 3. **Watering** Keep the soil consistently moist but not waterlogged. Water when the top inch of soil feels dry to the touch. Overwatering can lead to root rot, so ensure proper drainage. ### 4. **Fertilising** Feed your coleus with a balanced, water-soluble fertiliser every 2-4 weeks during the growing season (spring and summer). Reduce feeding in autumn and winter when growth slows. ### 5. **Pruning and Pinching** Regularly pinch back the tips of the stems to encourage bushier growth and prevent the plant from becoming leggy. Remove any faded or damaged leaves to maintain its vibrant appearance. ### 6. **Temperature and Humidity** Coleus prefers warm temperatures between 18-24°C (65-75°F). It enjoys moderate humidity, so mist the leaves occasionally or place a humidity tray nearby, especially in dry indoor environments. ### 7. **Pests and Diseases** Watch out for common pests like aphids, spider mites, and whiteflies. Treat infestations promptly with insecticidal soap or neem oil. Ensure good air circulation to prevent fungal diseases. ### 8. **Overwintering** In colder climates, coleus is often grown as an annual. However, you can bring potted coleus indoors before the first frost to overwinter it. Place it in a bright spot and reduce watering during this period. By following these care tips, your potted coleus will remain healthy and vibrant, providing a stunning display of foliage throughout the growing season. Happy gardening!

Coleus is an easy-to-grow indoor plant.

Watering: How and How Often?

Coleus prefers slightly moist soil without excess water.

• In spring and summer: Water 2 to 3 times a week when the surface of the soil begins to dry out. It is important not to let water stagnate in the saucer.
• In autumn and winter: Reduce watering to once a week, allowing the soil to dry out a few centimetres between waterings.

Use water at room temperature, preferably non-calcareous (rainwater or filtered water). In winter, when indoor air becomes dry, lightly mist the foliage or place a tray of water with clay pebbles nearby to maintain sufficient humidity.

Fertilisation: What Fertiliser and How Often?

To promote vigorous growth and vibrant colours, coleus requires regular nutrient intake. During spring and summer, you can apply a liquid fertiliser for green plants or geraniums every two weeks to support its development. In autumn and winter, it is best to reduce applications to once a month or even suspend them if growth slows down.

Pruning: Should You Pinch or Trim Coleus?

Regular pruning encourages branching and results in a more compact shape.

• Pinching young shoots: Once the plant reaches 10 to 15 cm in height, pinch (i.e., cut with your fingers) the tips of the stems to encourage the production of new branches.
• Removing flowers: Coleus flowers are insignificant, and their development drains the plant. It is recommended to remove them as soon as they appear to focus energy on the foliage.
• Removing damaged leaves: Regularly remove yellowed or dried leaves to maintain an attractive appearance and prevent diseases.

Repotting

A pot-grown coleus needs repotting every 1 to 2 years, usually in spring, when the roots begin to fill the pot. On this occasion, you can choose a slightly larger container (2 to 3 cm in additional diameter) and renew the soil to provide fresh nutrients.

What are the common problems of coleus indoors?

Although relatively hardy, coleus can be susceptible to certain pests and diseases, especially when grown indoors under inadequate conditions (excess moisture, overly dry air, poor ventilation).

Common Pests

• Aphids: often found on young shoots, they weaken the plant by sucking sap and can cause leaf curling. Solution: spray black soap on affected areas (15 to 30 g of black soap diluted in one litre of water).
• Spider mites: they appear in dry conditions and cause yellowing of the foliage, with fine webs under the leaves. Solution: increase ambient humidity by regularly misting the plant and placing a tray of water with clay pebbles nearby.
• Whiteflies (aleurodes): these small flying insects lay eggs under the leaves, causing general weakening of the plant. Solution: install yellow sticky traps and treat with black soap.

Aphids, spider mites, and whiteflies

Common Diseases

• Root rot: caused by overwatering and poor drainage, it manifests as sudden wilting of the plant and blackening of the base of the stems. Solution: space out watering, use a well-draining substrate, and ensure the pot has drainage holes.
• Powdery mildew: a fungus that forms a white powdery deposit on the leaves, favoured by excessive humidity and poor ventilation. Solution: remove affected leaves, improve ventilation, and treat with sulphur or a horsetail decoction.
• Botrytis (grey mould): it often attacks plants in overly humid and cold conditions, causing rotting of leaves and stems. Solution: space out plants to improve air circulation and avoid wetting the foliage during watering.

How to Prevent These Issues?

• Avoid overwatering, water moderately, and ensure proper drainage in the pot.
• Regularly mist the foliage to prevent spider mites.
• Avoid confined spaces and space out plants to reduce the risk of mould.
• Inspect the undersides of leaves to detect pests early.
• Remove diseased or yellowed leaves to limit the spread of diseases.
• Use natural treatments: black soap against aphids, nettle manure to strengthen the plant, horsetail decoction to prevent fungi.

How to propagate coleus?

Coleus can be easily propagated, mainly through cuttings, but also by seed. Cuttings are the quickest and most reliable method to faithfully reproduce a variety, while sowing seeds allows for new colour and shape variations.

Propagation by Cuttings

Propagation by cuttings is the most common technique for multiplying coleus, as it guarantees a plant identical to the parent. It can be done year-round indoors, but preferably in spring or summer, during active growth periods.

How to take coleus cuttings?

• Take a healthy stem 8 to 12 cm long, just below a node.
• Remove the lower leaves, leaving only 2 to 3 pairs of leaves at the top of the stem.
• Place the stem either in a glass of water for quick rooting (roots appear in 7 to 10 days) or directly into soil in a light, moist substrate.
• Keep at a temperature of 20 to 25 °C, in bright light but without direct sunlight.
• Transplant into a permanent pot once the roots are well developed (approximately 2 to 3 weeks after taking the cutting).

Coleus can be easily propagated in water

Seed Propagation

Propagation by seed (as described above) allows for coleus with varied colours, but the characteristics of the resulting plants may differ from the parent plant.

Our Decor Ideas for Incorporating Coleus Indoors

Which Pot to Choose?

With its vibrant and contrasting foliage, the coleus is a plant that stands out on its own aesthetically. To avoid an overly busy visual effect, it’s best to opt for a simple pot that will highlight its colours without creating decorative overload. A highly graphic and colourful foliage pairs better with pots in neutral and natural tones. White and light grey bring a contemporary and elegant touch, while terracotta or matte black offer a subtle contrast.

Use Colour Sparingly

If you feel drawn to a colourful pot, it’s better to choose a shade that complements one of the foliage tones rather than introducing an additional colour. The idea is to maintain chromatic harmony. A burgundy or plum pot will enhance a coleus with purple tones, while mustard yellow or olive green will accentuate more golden hues.

To avoid an overly cluttered visual effect, consider integrating your coleus into a balanced display:

• On its own: Placed on a shelf, coffee table, or windowsill, it immediately catches the eye with its vibrant foliage.
• In a composition: Coleus pairs perfectly with plants featuring solid green foliage, which softens its flamboyant appearance. For example, you can pair it with ferns, pothos, calatheas, or monsteras.

Coleus benefits from being paired with lush foliage plants (here, with a Monstera) for a jungle effect!