A full, trailing Petunia loaded with colorful blooms conjures images of summer, and with proper care, you can help your Petunias survive the winter and enjoy them once again when the temperatures warm up. Petunias are tender perennials, and they are only true perennials in USDA growing zones 9 through 11. They are generally grown as annuals in all other zones because they are not winter hardy.
In warm climates, continue to water and maintain your Petunias throughout the winter. The plants will naturally go dormant as the amount of light per day decreases. Scale back how often you water the plant as growth slows and once it is completely dormant, water only when the top several inches of the soil is dry. Be prepared to cover plants left outdoors if there is a steep temperature drop.
Cutting Back Petunias For Winter
Continue to prune as needed when your Petunias are actively growing. Once the plants go dormant, cut the plants back to about ⅓ of their size in anticipation of winter. After the plant starts growing again in the spring, any dead growth can be removed.
Petunias Winter Care in Pots
Petunias in pots can be left outdoors for the winter in warm areas, like zones 9 through 11. The pots will need to be moved to an indoor area that can offer some protection in all other zones. Getting the potted plants out of cold temperatures and into a basement or garage can protect the roots so that the plants will grow again in the spring. Trim back overgrowth and water when the soil dries out.
Watering Petunias in Winter
Once the plant is dormant, you will want to reduce how often you water. Wait until the soil is dry before giving the plant water, and just give it enough to soak into the ground. Actively growing plants need a nice, deep soak, but dormant plants are not very thirsty.
Growing Petunias Indoors
Petunias do not make the best houseplants, but it is possible to keep the plants growing and blooming throughout the winter. The plants usually go dormant, and they will try to take this rest as the amount of available sunlight lessens. If you want to keep your plant actively growing, place the Petunia in a warm and sunny spot and water when the top layer of the soil is dry.The plants need about 10 hours of sunlight each day to resist the urge to go dormant, so you may need to use grow lights to ward off dormancy.
Steps To Care For Petunias in Winter
Trim the Petunia back to about ⅓ of its size before the start of winter. In zones 9 through 11, Petunias can spend the winter outdoors but be ready to cover the plant if the forecast calls for temperatures below 40-degrees. The plant will need to be brought inside in the winter in colder regions. Petunias can be allowed to go dormant, or you can try to keep the plant actively growing, but be aware that it can be hard to prevent dormancy.
Step 1 - Cut the Petunia back to about ⅓ of its size.
Step 2 - Leave the plant outside in growing zones 9 through 11.
Step 3 - Transplant ground plants to a pot and bring potted Petunias into a protected area for the winter.
Step 4 - Potted Petunias can be allowed to go dormant, or with plenty of light and care, you can try to encourage the plants to continue growing.
Step 5 - Plants can be returned outdoors after the threat of frost.