Coleus

Coleus is grown for its colorful foliage, which can combine shades of green, yellow, pink, red and maroon. Its tiny flowers are not the main attraction of the plant. Plants form a mound up to 3 feet (91 cm) tall and wide. Many named cultivars differ in leaf color and in how much sun they can take.

Start seeds indoors, sown uncovered on a sterile growing mix kept at about 70 to 75 °F (21 to 24 °C). Seeds need light and warmth to germinate, so press them gently onto damp soil and do not cover them. Seeds usually take 10 to 15 days to germinate and 6 to 8 weeks to reach a size ready for transplanting. Harden seedlings off before moving them outside, and plant out after the danger of frost has passed, when nighttime temperatures are in the high 50s to 60s °F (about 14 to 20 °C).

Plants prefer part shade and will tolerate full shade, but they may wilt in full sun and become leggy in deep shade. Coleus also root easily from stem cuttings in water or clean potting soil. Some cultivars are sterile and must be grown from cuttings, and patented cultivars should not be propagated by cuttings.

Pinch out growing shoots of young plants often to encourage branching and dense foliage. Coleus needs soil that drains well, and it should not be left to dry out, so water at the base of the plant rather than on the leaves. Feed with an all-purpose soluble fertilizer in June, July and August, and avoid bloom-formulated fertilizers, which can make plants leggy. Cut back flower spikes to keep the foliage performing.

Aphids, whiteflies and spider mites are the main pests, especially on indoor plants. Mealybugs are also a concern. Fungal problems such as downy mildew, stem rot and root rot can follow wet foliage and overly wet soil. Cultivars that are not sun tolerant will bleach and discolor in full sun.

The leaves can cause minor skin irritation, and repeated, frequent contact can lead to a red rash. Coleus is rated as having low-severity poison characteristics.