Coleus is a tender perennial valued for its vibrant, patterned foliage, but it is typically grown as a warm-weather annual in most climates due to its sensitivity to cold. Since Coleus cannot survive freezing temperatures, gardeners in cooler regions must prepare it for winter if they wish to keep a specific variety. Overwintering requires specific preparation, including cutting back the plant, to ensure it survives until spring. This process involves deciding on the best method for saving the plant and executing the physical pruning before the first hard frost.
Deciding How to Overwinter Your Coleus
Before pruning, choose the method for carrying the plant through the winter. The two primary options are saving the entire parent plant or propagating new plants from stem cuttings. Saving the whole plant involves moving the established specimen indoors, which is suitable for smaller, healthy potted plants. This method allows the gardener to keep a larger, mature plant, but it requires substantial indoor space.
Taking stem cuttings is often the preferred and more practical choice, especially if the parent plant has become large, leggy, or shows signs of chronic pests. This method requires taking only small portions of the stem, allowing the original outdoor plant to be discarded. The resulting smaller cuttings are easier to manage, inspect, and take up less windowsill space than a full-sized parent plant. This choice dictates the severity of the initial cut back, determining if pruning is for rejuvenation or for propagation material.
The Physical Process of Cutting Back
Regardless of the chosen method, cutting back Coleus must be completed before outdoor temperatures consistently drop below 50°F, and well ahead of the first frost. Begin by ensuring all tools, such as scissors or pruning shears, are clean and sharp. This minimizes damage to the stem and prevents the transmission of pathogens, supporting the plant’s ability to heal quickly.
If the goal is to save the entire parent plant, it needs a substantial haircut to reduce resource demand and encourage bushy growth indoors. Trim back all stems by about one-third to one-half of their current height. Make the cut just above a leaf node to stimulate new side growth, which helps the plant adapt to lower indoor light levels and prevents it from becoming spindly or “leggy” during the winter.
For those choosing the cutting method, focus on harvesting healthy, non-woody stem tips that are four to six inches long. The most precise cut for propagation is made just below a stem node, the slightly swollen area where a leaf or pair of leaves emerges. This point contains a high concentration of meristematic tissue and growth hormones necessary for new root development.
A thorough inspection for pests is mandatory before bringing any plant material indoors, preventing infestations in the home environment. Carefully remove all dead leaves, spent flowers, and debris, examining the undersides of leaves and stem joints for common pests like aphids or whiteflies. If the parent plant is being saved, its root ball should be gently removed from its container and rinsed to dislodge any hitchhiking insects or eggs before being repotted in fresh, sterile potting mix.
Winter Care and Maintenance Indoors
Once the Coleus has been cut back and moved inside, the focus shifts to maintaining conditions that promote survival rather than vigorous growth. The plant needs bright, indirect light to thrive; a sunny south-facing window is ideal, though supplemental full-spectrum lighting may be necessary if natural light is poor. Insufficient light is the primary cause of legginess in overwintered plants.
Maintaining a stable temperature is important, as Coleus plants prefer room temperatures above 60°F and become stressed if the temperature consistently drops below this level. Place the plant away from cold drafts near windows or doorways, and away from heat vents that can rapidly dry out the foliage. The reduced light and cooler temperatures of winter naturally slow the plant’s metabolism, signaling a period of semi-dormancy.
This reduced metabolic rate requires an adjustment to watering and fertilization practices. Watering frequency should be significantly reduced compared to the summer growing season; allow the top inch or two of the soil to dry completely before watering again. Overwatering is the most common cause of failure for overwintered houseplants, leading to root rot in the cooler soil. Fertilization should be paused entirely, as the plant is not actively growing and excess nutrients can damage the roots.