How to Overwinter Coleus Plants

Coleus are popular garden plants due to their multi-colored foliage and exciting patterns. But since these plants aren’t cold-hardy, many gardeners treat them as annuals. If you’re tired of buying new plants each spring (or found a rare cultivar you love), you may be interested in overwintering your coleus plants.

We’ll cover how to help coleus survive frigid winter temperatures so you can enjoy them the following spring.

Why Overwinter Coleus Plants?

Coleus are tender plants that can’t tolerate frosts or temperatures below 32°F. So, if you live in a cold area, your plants won’t survive the winter outdoors. However, you can take steps to help them make it through the winter cold.

But why would you want to overwinter your plants rather than buy some new plants come spring? First off, some cultivars are difficult to find. If you’ve been tending to a cultivar you love, overwintering it will ensure you can continue growing it the following spring.

Saving coleus from one season to the next also helps you save some money on new plants. You can use these additional funds to try out a new variety or a different type of flower.

Finally, bringing plants indoors allows you to enjoy their beauty year-round. While many people think of coleus as garden plants, they can happily grow indoors as houseplants.

How to Overwinter Potted Coleus Plants

If your coleus is growing outdoors in a pot, the easiest way to overwinter it is to bring it indoors, pot and all. Follow these steps for winterizing potted coleus plants.

Check the Weather Forecast

Although coleus plants tolerate temperatures down to freezing, they become stressed when temperatures dip below 50°F. Bringing your plants indoors before these stressful temperatures increases the odds plants remain healthy.

Depending on your location, you should bring your coleus indoors sometime between late August and late October. Keep an eye on the weather forecast and move them indoors when nighttime temperatures drop below 50°F. If you miss this window, don’t fret. Just make sure to bring your plants inside before freezing temperatures arrive.

Look for Pests and Diseases

Before you bring your coleus indoors, check for common pests and diseases. If you spot sap-sucking pests like aphids and spider mites, wipe them off with a soapy rag or spray with neem oil.

Check for fungal diseases, including downy mildew and Botrytis. If you notice these diseases, avoid bringing your plant indoors.

Check Pot Size

Whether or not you’ll need to repot depends on the plant and pot size. You can bring single plants growing in small pots directly indoors as long as they are healthy.

However, if you are growing a coleus plant in a large container or have a mixed planting, it’s a good idea to repot before bringing it indoors. A small pot is easier to carry and fit in your home. Plus, separating multiple plants into individual pots creates better airflow, which helps limit disease development.

Repot If Necessary

If you choose to repot your coleus, choose a container just a bit larger than the plant’s root system. Selecting a too-large container increases the soil’s drying time and the likelihood of plants developing disease. Any container material works well, but make sure the pot has drainage holes.

Once you have your pot, choose a proper soil mix. Coleus plants hate sitting in wet soil, so a well-draining mix is key. Most pre-blended potting mixes designed for houseplants work well.

Remove your coleus from its current container and inspect the roots for signs of disease. If any roots are discolored or mushy, trim them off with sanitized pruning shears. Once the plant looks healthy, it’s ready for its new home.

Place a few inches of potting mix in the new container, then put the coleus in the pot. Fill the remaining empty spaces with potting mix, ensuring the top of the stem is at the soil surface. Water well.

Choose a Proper Indoor Location

Ideally, you would slowly acclimate your coleus to its new home rather than plucking it from a cold outdoor environment and immediately plopping it down in a cozy room. Proper acclimation might look like moving the pot from the outdoors to a garage or laundry room for a week and then to a warm bedroom.

However, I’ve moved outdoor plants directly to warm, indoor environments, and they’ve fared just fine. Coleus will likely drop a few leaves in response to the sudden change, but they’ll bounce back within a few weeks.

As far as indoor location goes, choose an area with bright, indirect light. A windowsill near a south-facing or west-facing window works well, as does the interior of a sunroom. I’ve kept coleus indoors in darker environments, and they’ve survived the winter. However, the lack of light often leads to duller foliage.

Provide Proper Care

Continue to provide your potted coleus with the proper amount of water. Since plants grow slower in the winter, they require less water than in the summer. That means you may only need to water your plant about once every one to two weeks.

If you’re unsure when to water, you can feel the top two inches of soil with your finger. If the soil is dry, it’s time to water. But if it’s still moist, wait to water. Remember, overwatering can be just as detrimental as underwatering!

Don’t apply any fertilizer during the winter, and keep your plant somewhere warm and bright.

Harden Off Plants for Outdoor Life

When spring rolls around, it’s time to reacclimate your coleus plants to life outdoors. This involves slowly exposing them to the temperatures, light, and wind present outside, a process known as “hardening off.”

Once temperatures are above 50°F, place your potted plants outdoors for a few hours during the day and bring the plants back inside overnight. Increase the amount of time the plants are outdoors by a few hours each day. After a week, you can leave the plants outdoors overnight, provided that the weather forecast is good.

How to Overwinter In-Ground Coleus Plants

If you’re growing coleus outdoors in your garden, you won’t be able to pick up a pot and bring it indoors. You can still overwinter plants growing in the ground, but the process differs. Rather than bringing the entire plant inside, you’ll take a cutting to overwinter indoors.

Since coleus plants are easy to propagate via stem cuttings, this process is simple! Even if you’re not in love with a particular variety, taking cuttings provides you with bright winter houseplants.

Take a Healthy Stem Cutting

To end up with a vibrant new coleus plant, you must start with a healthy cutting. Look at your plant and locate a stem with bright colors, rigid leaves, and no signs of pests or diseases.

Grab a sanitized, sharp pair of pruning shears or knife. Sanitizing the tool with a 10% bleach solution helps prevent the spread of disease.

Use your tool to make a clean 45° cut just below a leaf node. The cutting should be four to six inches in length.

Remove all leaves on the lower half of the cutting. You can gently pinch off the leaves with your fingernails or cut them off using a knife or pair of shears.

Dip the Cutting in Rooting Hormone

While this step is optional, dipping the end of your cutting in rooting hormone increases the chances it develops strong roots.

Dip the cut end of your cutting in the rooting hormone. The bottom of the cutting and the leaf nodes should come into contact with the hormone.

If you opt to skip the rooting hormone, move on to the next step.

Place the Cutting in Media

The next step is placing your cutting in a medium where it can form roots. Grab a pot with drainage holes and fill it with media.  A good rooting media provides the plant with support and moisture while allowing for adequate airflow. Peat moss, coco coir, and perlite are all good options. High-quality potting soil using peat or coco coir as a base is also a great choice.

Once your pot is filled with the media, poke holes using a pencil or pen. Insert the bottom two to three inches of each cutting into the media, then pack the media around the cutting. Ensure that none of the leaves are touching the media.

Water the media well.

Cover the Cuttings

Covering the cuttings with a plastic container or plastic bag helps seal in moisture and keep the plants healthy until they develop roots. This step is optional, but it increases the odds of successful rooting.

A plastic container works well for covering small cuttings and pots. If you’re dealing with a larger cutting, you’ll have trouble finding a big enough container. However, an alternative is covering your plants with a clear plastic bag—just make sure the plastic doesn’t touch the cuttings. Placing sticks in the media helps prop up the bag and keep it off the cuttings.

Place the Cuttings Somewhere Warm

Whether or not you cover your cuttings, place them somewhere warm and bright. However, keep them out of direct sunlight.

Check the media every day or two and water if necessary. You want the media to remain moist to the touch but not drenched.

The cuttings should begin to develop roots in two to three weeks. While you won’t be able to see the roots develop, cuttings that look healthy at three weeks post-cutting likely have roots.

Care for Coleus Cuttings

After the stem cuttings have developed roots, you should continue caring for them like any other coleus plant. Place them in a bright location out of direct light, and keep the soil moist.

If you want to repot the cuttings into another pot, you can do so anytime after they develop a healthy root system.

Transition Outdoors

When temperatures remain above 60°F, you can move your plants outdoors. However, you should harden off your plants beforehand.

Keep the coleus plants in the pots, and move the pots outside for a few hours during the day. Increase the amount of time the plants spend outdoors by a few hours each day. Eventually, you can leave the plants outdoors for an entire day and night. At this point, the plants are ready to begin life outdoors or be transplanted into your garden.

If you’d like to keep your coleus growing as an outdoor potted plant, all you need to do is place it in a suitable location. Many varieties thrive in partial sun, but the ideal light varies depending on the cultivar.

Planting directly into the garden is another option. If you opt for this route, choose a location with well-draining and loose soil. Remember, coleus like moist soil, but they hate sitting in water. As with potted plants, the ideal light depends on the variety. However, Partial sun is a safe bet.

Caring for Winter Coleus in Warm Climates

If you live where the temperature rarely dips below freezing (zone 10 and above), you may get away with keeping outdoor coleus alive throughout the winter.

Keep an eye on the weather forecast, and note any predicted cold spells or frost warnings. If it looks like the temperature will drop below 35°F, move potted plants indoors and cover in-ground plants with a few layers of row cover. Once temperatures rise, remove the row cover and move plants back outdoors.

If your plants look good, but an unusually hard freeze is in the forecast, you can still take the protective steps listed above. But if you’re worried they may die, you can take a stem cutting to propagate a new plant so you can still enjoy the vibrant colors if an unfortunate plant death occurs.