Lynne Forbragd, Extension Master Gardener, Anoka County
At the end of summer, my coleuses are at their peak and in full color. It’s really tough for me to see them die after the first frost. Coleuses are one of the easier annuals to overwinter. They are known more for their leaf color and variegation than for their flowers. They come in many shapes and sizes and can be planted in both shade and sun. With so many varieties available, you can add to your collection without repurchasing each year.
There are a couple of methods you can try to overwinter a coleus. As your coleus gets larger later in the summer, pinch off longer portions of the stem for cuttings, leaving two leaves at the base for continued growth. Plants can be pinched back up to a third of the plant height. This will prevent the plant from getting straggly and will encourage the plant to become full and strong. Place the cuttings in a vase of water to start rooting. Once rooted, pot up the plants for the winter season by fall.
Another method is to move the entire container indoors before the first frost. Before bringing them in, check for bugs, spray the plants down with a hose and make sure to wash off the underside of the leaves. Place in a sunny window or under a grow light. Continue to monitor for insects and spray with insecticidal soap if needed.
During the winter, coleus will lose its color. The plant that you brought indoors will lose some leaves and get straggly. This time of year the plant is entering its dormant stage and as tempting as it is, do not pinch it back. The goal at this point is to keep it alive by watering and monitoring for insects. As daylight increases, coleus will begin to sprout new leaves.
In March or April, prepare 4” pots with potting soil in planting trays. Pinch off stems, keeping a few leaves at the top, insert in the soil and water thoroughly. There is no need to place the cuttings in water this time of year; you can insert the stems directly into the soil and the plant will root in the potting soil. Place in a sunny window or under a grow light and keep the soil moist, but do not overwater. In a couple of weeks the new plant will adjust and soon you will be seeing new leaves and color.
Depending on the variety, plants can double in size by the time they are ready for planting in May. Harden off the plants before planting them outside by taking the plant trays outside on warm spring days and bring them indoors at night. Do this for one to two weeks to acclimate the plants for the growing season.
While there is a little effort in overwintering coleuses, you will automatically have a variety of coleuses to plant in the spring. If you get too many, share with your friends and family.