Outside, the coleus is a tropical plant hardy in zones 10 and 11. Coleus are treated as summer bedding or annuals plants everywhere else. Indoors, they are grown as houseplants. In any garden setting, coleus are grown and appreciated for their colorful leaves.
The leaves come with a wide variety of leaf margins, from plain to ruffled, colors ranging from reds, yellows, and oranges to greens and purples, all in many sizes. Some coleus plants grow to be large and upright while other varieties creep along, spreading its branches.
Outside, coleus plants grow best in part shade. They tolerate full shade but will become leggy and, eventually, thin out. The leaves of coleus planted in full sun will become scorched and faded. Gardeners should avoid planting coleus in gardens with a western exposure. Gardeners unsure of light exposure in a garden can test it by planting a coleus in a container. If the plant becomes leggy or faded, it will be easy to move, thereby adjusting the location.
Indoors, coleus plants like bright light but not hot direct sun. Avoid western facing windows, unless the coleus plant is set well away from the window or protected by a curtain. Coleus plants tolerate minimum indoor temperatures to 60°F and humidity levels to 30 percent. Coleus are not houseplants that require the steamy moisture or warmth of bathrooms or kitchens.
Coleus grows best in moist, well-draining soil, whatever the location. Coleus have fibrous roots and like soil kept moist and cool. Outside top-dress the soil with mulch in a garden planted with coleus.
When planting coleus outside in a garden bed, space coleus 10 – 12 inches apart. Read the label for specific cultivar information. Gardeners should plant coleus, like any annual plant, in soil amended with organic matter.
For indoor/container gardens use an all-purpose, quality pre-packaged potting soil. Plant coleus in pots and water with a balanced fertilizer or one higher in nitrogen. Fertilizer in time-release pellets is an excellent choice for all types of gardeners.
Coleus are low maintenance plants, whether planted indoors or outside, in containers or in the ground. Gardeners can keep plants healthy by removing flowers and dead leaves periodically.
Indoor gardeners should cut back stems to encourage a bushier plant and repot the plant every 2 years or as the plant outgrows the container.
Outdoors, slugs may bother coleus when they are planted in a very shady area. Indoor gardeners may see spider mites, mealy bugs or white fly. These are plant bugs traditionally found on many houseplants and can be treated using insecticidal soap.
Coleus plants were appreciated by Victorian gardeners then had a resurgence in the 1960’s and 1970’s. Today, many container gardeners have large coleus collections.