The plant commonly known as Coleus (Plectranthus scutellarioides) is popular for its vibrant, ornamental foliage. Its leaves display a spectacular range of colors, from chartreuse and pink to deep burgundy and crimson, making it a favorite for containers and garden beds. Whether this striking plant is an annual or a perennial is a frequent source of confusion, and the answer depends entirely on the climate in which it is grown.
The Technical Answer Perennial in Warmer Climates
The botanical classification of Coleus is that of a tender herbaceous perennial. A perennial plant lives for more than two growing seasons, returning year after year. The native habitat of Coleus is the tropical and subtropical regions of Southeast Asia, where the climate is consistently warm and humid.
In these frost-free environments, the plant naturally survives indefinitely, often developing a woody base. Only in the warmest parts of North America, specifically USDA Hardiness Zones 10 and 11, can Coleus successfully live outdoors year-round without protection. This means that in places like southern Florida, coastal California, and Hawaii, Coleus functions as a true perennial.
The Practical Answer Treatment as an Annual
For the majority of gardeners, Coleus is treated as an annual, a plant that completes its life cycle and dies within a single growing season. This usage is necessitated not by the plant’s biology, but by its extreme sensitivity to cold temperatures. Coleus is a heat-loving plant that thrives when temperatures are consistently above 60°F.
The plant is highly intolerant of frost; even a light freeze will cause the foliage and stems to collapse and die. In most temperate regions (USDA Zones 9 and below), cold autumn and winter temperatures dictate that the plant must be replanted every spring. Garden centers label Coleus as an annual because this reflects its realistic lifespan in cooler climates, making the designation a practical gardening term.
Extending the Life Cycle Overwintering and Cuttings
Since Coleus is biologically a perennial, gardeners can bypass its “annual” death by bringing it indoors before the first hard frost. This process, known as overwintering, is the simplest way to save a favorite variety. To overwinter the entire parent plant, it should be potted and moved indoors when night temperatures regularly drop into the 50s Fahrenheit.
The plant requires a location with bright, indirect light, such as a south-facing or east-facing window. A grow light may be necessary during the short, dark days of winter. Maintaining high humidity (ideally between 50% and 70%) is beneficial, which can be achieved using a pebble tray or small humidifier. Watering should be reduced during winter growth slowdown, allowing the top inch of soil to dry out between applications to prevent root rot.
Cuttings
A second, often preferred method for preservation is taking softwood cuttings in the late summer or early fall. This technique is popular because Coleus belongs to the mint family (Lamiaceae) and roots easily. To propagate, a gardener takes a three to four-inch cutting from a healthy stem tip, removes the lower leaves, and places the stem into a glass of water or moist potting mix.
Within one to two weeks, the cutting will develop a robust root system in water or root in soil. These small, new plants require bright, indirect light throughout the winter. They can be planted outdoors the following spring once all danger of frost has passed. Taking cuttings allows the gardener to save favorite varieties without dedicating space to a large, mature plant indoors.