Petunias are absolute classics for window boxes, and you’ll often spot them brightening up garden beds, too. But as the seasons shift, these beauties eventually have to face the frost. Can they handle the big chill, or should you be clearing some space for them indoors? Here’s the lowdown on how to help your petunias survive the winter.
Are Petunias Cold-Hardy?
Short answer: not really. Petunias hail from South America, where they’re used to soaking up the sun in a much warmer climate. Because they aren’t built for freezing temperatures, you’ll need to move them to a frost-free spot once the thermometer starts to drop.
Pro Tip: You might notice some “hardy” perennials surviving outside in very mild climates (like coastal areas or wine country), but petunias are pretty sensitive. Even in those spots, they usually can’t handle a real cold snap.
Winter Care Checklist
If you want your petunias to feel right at home in their winter quarters, here’s what you need to do:
- Temperature: Aim for a cool 40°F to 50°F (5°C to 10°C).
- Light: Find them a bright, sunny spot.
- Fertilizer: Skip it! They don’t need the extra nutrients while they’re resting.
- Water: Keep it light—only water when the soil is dry.
- Pruning: Trim the stems back to about 6 to 8 inches.
Pro Tip: Keep a close eye on your plants throughout the winter to make sure no pests or diseases are trying to move in.
To be honest, most gardeners treat petunias as annuals and just buy new ones each spring. Overwintering them can be just as much work as starting from scratch!
Saving Their Energy
If your petunia starts putting out new growth or buds during the winter, I know it’s tempting to let them bloom—but you should actually pinch them off. Flowering takes a ton of energy that the plant should be using to stay strong and healthy. Of course, if you’re planning on tossing the plant at the end of the season anyway, go ahead and enjoy those last few flowers!
Moving Back Outdoors
Once you’ve successfully coached your petunias through the winter, they’ll be itching to get back into the sun. But don’t rush it! Wait until the threat of frost has completely passed (usually after Mother’s Day in many regions). Those late-spring frosts can easily kill off tender new buds.
To prevent the leaves from getting “sunburned,” give them a little transition period. Start by placing them in a sheltered, bright spot for a few hours a day before moving them into full sun. And remember: as the weather heats up, your petunias are going to get a lot thirstier!
