Coleus Seeds

Coleus (Coleus scutellarioides, also sold as Coleus blumei or Plectranthus scutellarioides) is a tropical member of the mint family grown purely for its dramatic foliage rather than its flowers. Each leaf is a living mosaic of red, green, burgundy and gold, edged and veined in contrasting tones, making it one of the most colourful ways to light up shaded spots in beds, borders and pots.

Planting

Start seed indoors about 8 weeks before your outdoor planting date; in warm climates sow 8-12 weeks ahead and plant out only well after frost risk has passed. The seeds need light to sprout, so surface-sow and barely cover with vermiculite. Germination takes 10-20 days at 21-24 C, then grow on cooler at 18-21 C. Transplant once the soil has warmed (above ~16 C) and space plants about 30 cm apart in part shade or dappled light.

Fertilizing

Apply a balanced granular fertilizer at planting, then feed monthly through the main growing season to push lush foliage. An all-purpose soluble feed such as 24-8-16 or 17-4-17 works well. Avoid high-phosphorus bloom formulas, which make the plant leggy rather than bushy.

Care

Never let plants dry out: keep root balls moist for the first 7-10 days, then water once the top 2.5 cm of soil is dry; containers may need daily watering. Use a soaker or drip line to keep foliage dry and prevent downy mildew, stem rot and root rot. Pinch off the top 5 cm above a leaf node when plants reach about 15 cm for bushier growth, and remove flower spikes to keep the plant vigorous. Watch for mealybugs, aphids, whiteflies and spider mites.