Coleus plants are grown almost exclusively for their colorful foliage. Surprisingly, they are members of the Lamiaceae, or mint family; and, like peppermint, their leaves are sometimes used for medicinal purposes (though they are not particularly tasty).
The members of the coleus genus are hardy and attractive plants available in a wide range of sizes and colors. Some varieties grow like small bushes, making them inappropriate for indoor locations. Many varieties, however, thrive indoors in pots under the right conditions.
Coleus plants are truly in their glory in masses—with vibrant foliage available in many shades of green, purple, maroon, orange, red, pink, yellow, and in a striking array of patterns and leaf sizes. Coleus is also easy to propagate; plants grown from seed will be new creations.
Although the growing guidelines described here make it possible to grow coleus indoors year-round, coleus is often grown as an annual and discarded once it becomes leggy (a problem that can often be contained by pinching off new growth).
Indoor coleus does best under the following conditions:
- Light: Coleus loves bright light, though it's best to avoid direct midday sunlight. Too much sun will fade colorful foliage.
- Water: Keep soil continuously moist throughout the year, but reduce watering in winter. High humidity is preferred.
- Temperature: Above 60 degrees Fahrenheit is preferred in the summer. In winter, temperatures must be above 50 degrees Fahrenheit.
- Fertilizer: Feed in spring with slow-release pellets or weekly during the growing season with liquid fertilizer.
You can propagate coleus by cuttings or by seed. Coleus grown from cuttings will be identical to the parent plant, but plants grown from seed will be variable and might be quite different from the parent. Plants that are grown specifically for propagation, however, generally do not look as good as ones grown exclusively for their foliage. The energy of flowering usually saps the plant of some vitality, which is why many growers pinch off flowers.
A large coleus will reach 2 to 3 feet in height. They grow rapidly in the spring, but many people don't overwinter them, so they never bother repotting the plant. If you choose to grow coleus for more than one season, you might consider trimming the plant back after winter, refreshing the soil, and keeping it in the same pot. Alternatively, you can repot into a pot one size larger.
The 60 species of coleus are native to Asia and Malaysia. However, virtually all of the coleus available are derived from the single C. Blumei species, crossed with a few other species. Hybridizing work within this group has been extensive—there are literally hundreds, if not thousands, of cultivars. Buy coleus for its foliage and don't worry too much about its parentage.
Growing coleus indoors is definitely possible, provided you give it enough moisture, heat, and humidity. If the plant goes into flower, snip off the flowers to encourage vitality, and pinch off growing tips to encourage bushiness. Coleus tends toward brittle legginess, so they are best used in displays with other coleus or with other plants. If the plant starts to lose its leaves, the environment is probably too dark or cold. If foliage color fades, the plant is probably receiving too much sunlight.