Can’t bear to part with your favorite coleus when fall frost looms? You don’t have to! Coleus (Solenostemon species) are among the easiest plants in the world to root from cuttings, and getting them to overwinter indoors is almost as simple.
Step 1: Six weeks before your first autumn frost, take four-inch-long tip cuttings from your favorite coleus. Strip the leaves from the bottom two inches of each cutting. Stick the bare portion of each stem into a small pot of sterilized potting soil (1 cup of soil should do). Make sure you have at least one leaf node buried in the soil. Keep the potting mix damp but not soggy, place the cuttings in bright light but out of direct sun, and you should have well-rooted plants within four weeks. If not, try again. (While it’s true you can root coleus cuttings in a glass of water, the roots are fragile and easily injured when you pot up your plants. It’s so much easier to start with the roots in good soil.)
Step 2: Once your cuttings are well-rooted, pot them up into pots that hold two to three cups of soil. Move them to the sunniest window of your house (or set them up under artificial lights for the winter). Make sure the plants remain at temperatures above 60 degrees F. for the entire winter. Coleus hate to be cold!
Step 3: Once your plants are settled on their windowsills, add a half-strength dose of timed-release fertilizer to the soil surface of each pot. (Read the package label for recommended dosage — no guessing allowed!) Pinch the growing point out of each tip to produce stronger, bushier plants.
Step 4: This is very important — don’t love your plants to death! Coleus should be kept rather dry over the winter to avoid rotting their roots. Remember, these are tropical plants that prefer sun and heat. They don’t take kindly to cold, wet soil, so water only when the pot seems fairly light and the soil surface is completely dry. (You’ll get the hang of it with a little practice.)
Step 5: The low light levels of mid-to-late winter are tough on coleus. They long for the tropics, where the sun shines 12 hours a day. If your plants are yearning, pleading, begging for more light (you’ll know by the way they lean toward the sun on weak, spindly stems and give off small, pitiful whimpers whenever you enter the room), consider investing in inexpensive grow lights to supplement your natural light.
A special note: Due to changes in light level, coleus sometimes alter their leaf colors in winter. The new shades can be less than dazzling (OK, I admit it, they can be rather murky!). They may look nothing like the beautiful plants you remember from the garden. Don’t throw them away! They will recover their vivacious personalities once they see some serious sunlight. (Would this be a good time to mention that, for obvious reasons, you might want to label your plants when you take the cuttings?)
Step 6: You’ve made it through winter. Now what? Acclimating indoor plants to the outdoors is best done in stages. Start by placing your coleus in bright shade on days when temperatures are above sixty degrees. Bring them back in at night if temperatures drop below 55 degrees F. Gradually ease the plants into more sun, making sure to keep up with their increasing water needs. Don’t drown them, though. Indoor plants often wilt to protect themselves from sun that’s stronger than they’re used to. If the root-ball is well-watered, then the plants need less sun, not more water.
Step 7: You’ve loved, sheltered, and tended your babies all winter long, and you’re dying to get them into the garden. Are they finally ready for planting? Tropical plants like coleus should be placed in the garden once night temperatures are sure to remain above 50 degrees. Don’t rush to plant sooner. You’ll only risk damage to their tender little leaves. Once the weather’s warm, they’ll grow like crazy and you can be proud you grew them yourself!