Coleus is a shade-tolerant plant in warm climates but thrives in full sun in cooler environments. When growing coleus indoors, use a time-release fertilizer to promote growth and maintain room temperatures of 70 degrees Fahrenheit or higher. Plant young coleus plants in a 4-inch container, and allow the root system to develop before transplanting to the garden or a larger container.
Maintain moist soil by watering the plants regularly, and mix water-storing gardening crystals into the soil. Avoid cedar mulch, as cedar is toxic to coleus. To promote strong roots, add a root stimulator to the soil before planting. When soil temperatures reach 60 F, plant coleus outdoors in a partially shaded location.
For optimum leaf color, grow the plant in a location with full morning sun and shade in the afternoons and evenings. In regions with cold winters, take cuttings from the plant in autumn to regrow the following year. Root the cuttings on a sunny windowsill over winter, and plant the cuttings as recommended in the spring.
Create bushy coleus by pinching the tips of each plant back when the plant is young, and prune the plant when it becomes overgrown in mid-summer. To create a display, place three to four coleus plants in a 10- to 12-inch container.