Once a Victorian staple and later disparaged, Coleus has made a big comeback. It has come out of the shade and into the sun with the development of sun coleus.
Coleus plants which are annuals in most areas provide color over the entire gardening season. They can be used as individual plants or form a brilliant tapestry when massed in a garden. They make excellent container specimens and low maintenance houseplants. Some gardeners like to collect the many variations available.
Coleus is a tender tropical plant, native to Africa and Southeast Asia and it needs warm temperatures to grow. They should not be set outside until the nighttime temperatures stay above 60 degrees. Leaf damage can occur when temperatures are in the 40's and a light frost will destroy the plant. Planting out when the weather is too cool often results in stunted growth. On the other hand, they can take an enormous amount of heat as long as they are in good soil kept evenly moist. Be sure to harden them off before you plant them out and protect them from the wind.
Plant Coleus in well-drained soil and keep them constantly moist, but not soggy. Cool damp soil will lead to root rot. Use a high nitrogen fertilizer to promote foliage growth, but do it at half strength for the best color development.
Pruning is an important task to insure a well-branched, bushy plant. Pinch the growing tips when they are young. It is your preference whether to pinch off the blooms or to keep them, but leaving them on does cause the stems to elongate. In mid-summer, it is often necessary to prune the plant to keep its shape. They will become leggy if they are not pruned.
Coleus leaves may be green, pink, yellow, black (very dark purple), maroon and red. The Coleus color that you select in the greenhouse may change radically over the season. The same variety will often vary in appearance in two different locations in your landscape. More pigmentation develops the more sun the plants are subjected to as the pigment forms to protect the leaves. In full sun, pay constant attention to their water needs, probably watering every day. Even sun Coleus perform better when kept out of the mid-day sun. Sunscald may occur resulting in bleaching of the leaves. No Coleus do well in deep shade as a certain amount of light is necessary to develop pigment.
Coleus come in an amazing number of leaf shapes and markings. Many have a spade shape, either broad or narrow. Some varieties have ruffled ('Red Ruffles') or lobed ('Ducksfoot') leaves. Leaf markings range from flecks or blotches to almost solid shades of burgundy and chartreuse. The larger the leaf usually means the larger the plant, often reaching more than three feet. Some varieties form neat mounds and some such as 'Chocolate Drop' are trailing.
There are many series and hundreds of named varieties of Coleus. The names can be quite amusing like 'Bada Bing' or 'Flapdoodle.' Those that are vegetative propagated (from cuttings) are for the most part sun tolerant. The variety 'Kong' is an exception as it needs to be grown in the shade. Seed grown Coleus found in multipacks are generally shade plants.
One of my favorite Coleus varieties is 'Alabama Sunset,' which has a combination of chartreuse and rust and can get as big as a small shrub. 'Envy' gets up to three feet tall with avocado green leaves. 'Sedona' stays true to its burnt orange or copper color through the season. New varieties come out each year so pick a few that appeal to you.
Coleus is one of the easiest plants to start from cuttings so you can use some of your prunings to get more plants. It is best to pot up the rooted cuttings in 4-inch pots to develop a good root system before planting them out. It is okay to do this for your personal use, but it is illegal to sell named varieties at a plant sale. Taking cuttings is a good way to save a favorite variety over winter.