Plectranthus scutellarioides

Sowing and care guidance

Start Plectranthus scutellarioides seeds indoors ahead of the last frost. Sow on the surface of a fine, moist medium and press gently—do not cover, as light aids germination. Maintain steady warmth (around 21–24°C) and even moisture; use a gentle mist to avoid disturbing the seed. Germination usually occurs in 10–20 days. Prick out seedlings at the first true leaves and grow on in bright, filtered light. Harden off, then transplant after frost when nights are reliably warm, spacing to allow good air flow as per packet guidance. Plant into humus-rich, well-drained soil kept evenly moist, and shelter from harsh midday sun. Pinch tips to encourage compact growth; feed lightly to preserve vibrant foliage. Plants range from compact to medium depending on cultivar.

• Surface sow; light aids germination; 21–24°C warmth and steady moisture support even sprouting.
• Harden off, then transplant after last frost when nights stay warm; provide partial shade and midday sun protection.
• Pinch growing tips to promote bushiness; remove flower spikes if foliage display declines.
• Suitable for containers; use a free-draining potting mix and water consistently.
• Grown primarily for ornamental foliage; colour holds best with filtered light and moderate feeding.

How do I grow Plectranthus scutellarioides from seed?

Sow Plectranthus scutellarioides seeds indoors ahead of the last frost in a clean seed mix. Press the tiny seeds onto the surface (they need light), mist to settle, and keep covered with a clear lid for humidity at 21–24°C until germination, usually 7–14 days. Provide bright, indirect light to prevent stretching. Transplant seedlings to individual cells when they have true leaves, then harden off and plant out after all frost risk, once nights are warm. Choose partial shade to filtered sun, in humus-rich, well-drained soil that stays evenly moist. Space for good airflow—often 20–40 cm depending on cultivar—and pinch tips to encourage a compact habit.

When should I start coleus seeds indoors?

Start coleus seeds indoors about 8–10 weeks before your expected last frost so plants are sturdy by outdoor planting time. Germination and early growth are quickest in steady warmth (around 21–24°C) with 12–16 hours of bright light. Move seedlings outside only after the last frost, when nights remain consistently mild and the soil has warmed; acclimatise them over 7–10 days to brighter light and outdoor breezes to reduce transplant shock.

Should coleus seed be surface-sown or lightly covered?

Surface-sow coleus seed; do not bury it. The dust-like seed benefits from light exposure for reliable germination. Firm gently onto a fine-textured, moist seed mix and, if desired, sift a very thin veil of fine vermiculite to retain humidity without blocking light. Use a humidity dome or clear cover until most seeds sprout, ventilate daily to prevent damping off, and water from below or mist carefully to avoid dislodging the seed.

What is the best light for coleus seedlings, and can mature plants grow in full sun?

Seedlings thrive in bright, indirect light or under grow lights for 12–16 hours daily; keep lights close enough to prevent leggy growth but not so close that leaves scorch. Mature coleus prefer partial shade to filtered sun, with protection from harsh midday sun that can bleach or scorch foliage. In cooler or overcast periods they tolerate more sun, while in intense heat they benefit from dappled shade; morning sun with afternoon shade is a reliable balance in most gardens.

What soil mix and container care do coleus need, and how should I water them?

Use a humus-rich, well-drained potting mix that holds moisture without becoming waterlogged; a quality mix amended with compost or coco coir for moisture and perlite or pine bark for drainage works well. Choose containers with generous drainage holes and avoid overpotting to keep roots active. Keep the medium evenly moist—allow just the top centimetre to dry slightly between waterings—then water thoroughly, letting excess drain away. Feed lightly during active growth, rotate pots for even shape, and pinch stems periodically to keep plants bushy and compact.

Are coleus toxic to pets?

Coleus (Plectranthus scutellarioides) is often listed as potentially toxic to pets if chewed or ingested. To reduce risk, position plants where pets cannot access them and promptly tidy fallen leaves or prunings. If pet safety is a priority, consider placing containers out of reach or choosing alternative foliage plants known to be pet-safe.

This guidance offers general cultivation information applicable across climates. Outcomes vary with microclimate, soil structure, fertility, drainage, and seasonal cues such as temperature, moisture, and the period after the last frost or when soil is workable. Product pages provide variety-specific instructions—covering sowing depth, spacing, timing, and other details—based on supplier specifications and testing. Where conditions differ, the relevant product page presents the most accurate guidance for that selection.

Starting and growing coleus from seed

Plectranthus scutellarioides seeds bring vibrant foliage to containers and borders. For reliable results, start indoors when days are lengthening, or sow outdoors after the last frost when nights are mild. Use a fine, sterile seed-starting mix; surface-sow and press gently, as these seeds need light to germinate. Maintain consistent moisture and warmth (around 21–24°C). Germination often occurs in 7–14 days. Provide bright, indirect light to prevent stretching. Transplant when roots hold the plug together and acclimatise seedlings before setting out. Plant in well-drained soil with partial shade; in cooler summers, morning sun is suitable, while during hot spells, afternoon shade helps preserve colour. Space 20–30 cm apart. Pinch young tips to encourage branching and fuller plants. Keep soil evenly moist but never waterlogged, and feed sparingly for steady growth. In mild climates, autumn sowing for indoor displays may be possible. Cuttings can be taken before first frost to carry favourite selections through winter.