Coleus is a popular ornamental plant, celebrated for its vibrant and diverse foliage. Gardeners feature these plants in beds, borders, containers, and hanging baskets due to their eye-catching colors and patterns. As a staple in many landscapes, a common question arises regarding its longevity: will it return year after year, or is it a plant that needs to be replanted annually?
Understanding Coleus’s True Nature
Botanically, Coleus, known scientifically as Plectranthus scutellarioides (or formerly Solenostemon scutellarioides), is classified as a tropical perennial. This means that in its native environment, the plant naturally lives for more than two years, often growing as a bushy, woody-based evergreen. Its origins trace back to tropical regions of Southeast Asia and Australia, including areas like Malaysia and India. In these warm, frost-free climates, Coleus thrives year-round.
How Climate Affects Coleus
Despite its perennial classification, Coleus is commonly cultivated as an annual in many parts of the world due to climate limitations. This is primarily because Coleus plants are highly sensitive to cold temperatures and cannot tolerate frost. Even temperatures dipping into the 50s Fahrenheit can cause stress, and a hard frost will cause the plant to die back completely. Consequently, Coleus is reliably perennial only in warmer USDA Plant Hardiness Zones, specifically Zones 10 and 11, where freezing temperatures are rare or nonexistent. In any zone colder than this, the plant will succumb to the first significant cold snap of autumn.
Strategies for Overwintering Coleus
For gardeners in colder zones who wish to preserve their favorite Coleus plants, bringing them indoors before the onset of cold weather is an effective strategy. Potted Coleus should be moved inside when nighttime temperatures fall below 60°F, or before the first frost.
Once indoors, provide the plant with bright, indirect light, ideally near a south or southeast-facing window. Maintain indoor temperatures above 60°F, and aim for humidity, which can be achieved through misting or using a small humidifier. Watering frequency should be reduced during winter, allowing the top inch of soil to dry slightly between waterings, but never letting it become completely dry. Regularly inspect the plants for common indoor pests like spider mites or mealybugs, addressing any infestations promptly.
Propagating Coleus for Continued Enjoyment
An effective method for ensuring a continuous supply of Coleus, particularly for those in regions with cold winters, is propagation through stem cuttings. This process is straightforward.
Taking Cuttings
To take a cutting, select a healthy stem that is 4 to 6 inches long and make a clean cut just below a leaf node. Remove any leaves from the lower half of the cutting, ensuring no foliage will be submerged if rooting in water.
Rooting and Potting
Cuttings can be rooted in either water or a moist potting mix, with roots developing within a few weeks. Once roots are 1 to 2 inches long, the new plants are ready to be potted into their own containers.