Coleus likes bright light at all times, including several hours a day of direct sunlight. Warm temperatures are fine, although above 65 degrees, a humidity tray is helpful. Just put 3 or 4 inches of small pebbles (gravel) in a saucer to be placed under the plant. Keep water in the pebbles (just below the pebbles top) to create a vapor around the plant. The tray is best the width of the widest part of the plant. The plant is subject to temperatures below 55 degrees, leaves are in danger of wilting and dropping off. Always, keep soil mix moist, if mixture is allowed to dry out, the leaves will collapse, and fall off eventually. Propagation is recommended, since young, freshly rooted plants overwinter much better than older plants. Tip cuttings 2-3 inches long taken in early fall will root easily in potting mixture. Rooting will take place in two weeks if kept in a warm, brightly lit position, with direct sunlight. Water cuttings enough to make the mixture moist, but allow the top half-inch of the mix to dry out completely between waterings. In hot, dry rooms mist spray plants with water to avoid spider mites. All coleuses should have their growing tips nipped out occasionally as needed, to help them remain bushy.

Hope this helps.