Calibrachoa, or as many of us lovingly call them, “Million Bells,” originally hail from the sunny landscapes of South America. While they absolutely thrive in our summer gardens when given the right spot, they are total divas when it comes to the cold—they just can’t handle freezing temperatures. Because of this, most gardeners treat these beauties as annuals and buy fresh plants every spring. However, if you’ve got a favorite color you’re not ready to part with, you can actually overwinter them with a little bit of effort!
How to Successfully Overwinter Your Million Bells
Since these plants are super sensitive to frost, they must be moved indoors to stay warm. Here’s your game plan for keeping them happy until spring:
- Before moving them inside, give your Million Bells a good haircut, trimming them back to about 4 inches (10 cm) in height.
- Find a bright spot for your containers.
- Aim for a room temperature of around 57°F (14°C).
- Ideal spots include sunrooms, cool bedrooms, or bright stairwells.
- Don’t let the root ball dry out completely, but water very sparingly.
- Skip the fertilizer during the winter months.
- In the spring, don’t rush them back outside! Gradually acclimate them to direct sunlight again.
- Wait until after the last frost (usually mid-May) before planting them back outdoors for good.
- Keep a close eye out for uninvited guests; aphids and whiteflies are common pests in winter quarters.
Starting Million Bells from Seed
If you collected seeds from your plants last fall but didn’t want to save the whole plant, you can start your new garden babies on a sunny windowsill as early as January. Use trays filled with rhododendron soil, as Calibrachoa love a slightly acidic environment. Cover your seed trays with plastic wrap to keep the humidity high—that warm, moist “mini-greenhouse” effect really helps speed up germination. Just remember to lift the plastic daily to let in some fresh air and prevent mold. You should see sprouts in about two weeks! Once your seedlings reach about 8 inches (20 cm), they’re ready to be moved into their own individual pots.
Since Million Bells are so cold-sensitive, keep them indoors until the threat of frost has passed in mid-May. You can, however, start “hardening them off” before then by giving them a few hours of outdoor sun and fresh air each day to get them ready for the big move.
