Can Petunias Survive Frost? | 5 Ways to Protect Them

Petunias are colorful and gorgeous plants that everyone loves, but they do not do well when there’s frost outside. Petunias don’t usually survive heavy frosts but may survive a light frost if they are healthy. There are things you can do to protect them and increase their chance of survival.

This article will explore how to protect petunias from frost at home.

How to Protect Petunias from Frost

There are numerous ways to protect your petunias from frost, and they include:

1. Use Mulch

A light layer of mulch can protect your petunias because it insulates the soil and keeps the plants much warmer. Try mulch made of straw, leaves, or hay for good results.

2. Water Properly

Always make sure your petunias are well-watered before the first frost. This will help to protect the plant cells during the frost.

3. Grow Them in Pots

If you grow petunias in pots instead of the ground, you can simply bring them indoors when you know temperatures will dip below a certain level.

4. Cover the Plants

Nurseries have several types of covers for plants, some of which are plastic and others made out of fabric. It’s a good idea to own one of these so you can cover the petunias when a frost is expected.

5. Choose Varieties That Are More Frost-Resistant

Some varieties of petunias are more resistant to frost than others, so choosing them is smart. These include varieties such as Tidal Wave Silver and Supertunia Vista Bubblegum.

When to Protect Petunias From Frost

Protecting petunias from frost begins before you even purchase them. Choosing the right variety for your growing zone and planting them in pots are great first steps. Petunias do best when grown in zones 3-11, so if you’re outside of these zones they may not work well.

Remember that petunias have paper-thin petals that make it difficult to survive frost, and as soon as you learn there’s going to be frost in your area, you should start making plans regarding what to do so they can be better protected in the end.

Will Petunias Come Back After a Frost?

In most cases, petunias will come back after a frost, provided you take good care of them. Once frosts have passed, trim off any damaged leaves and system and water them well.

Make sure they are getting at least 6 hours of sunlight per day. If the plant has developed yellow leaves, feed them with a nitrogen based, liquid fertilizer.

Will a Covered Porch Protect Petunias from Frost?

Petunias are generally protected from frost when housed on your porch, especially if there are no strong winds. Make sure they are placed at least 3 feet from the edge of the porch, or against a wall.

If your porch is small, consider bringing petunias indoors to protect them from frosts. Once the weather has warmed and frosts have passed you can move them back outdoors to get more sun.

The Best Time to Plant Petunias

Early spring is the best time to plant your petunias, but you’ll need to wait until after the very last frost to plant them. You’ll also want to make sure the flowers are planted only in soil that is a minimum of 60 degrees Fahrenheit.

If you start your petunias from seeds, plant them inside roughly 10 weeks before the last spring frost is expected to occur. Remember that the threat of another frost has to be completely gone before you plant your petunias, and the warmer the soil, the better.

3 Tips to Care for Petunias in Winter

There are several things you can do to take care of petunias during the winter. They include the following:

1. Avoid pruning and heavy watering

Petunias need light until they become dormant. When they’re dormant, never prune or fertilize them until spring arrives. Reduce the amount of water you give them each week until the leaves start to fall off the plants.

When that happens, stop watering altogether and keep them in a cool place until mid-February. At that time, place them in sunlight again and start watering them slowly.

2. Bring Them Indoors

Ideally, petunias will be indoors for the winter months. They’ll be easier to take care of when it’s cold, and you’ll never have to worry about what to do when a frost is expected. If you can’t bring them indoors, the next best thing is to cover them with some type of cover made specifically for plants.

3. Propagate Cuttings

If your petunias are growing in the ground, and before the first frost occurs, cut the stems down to 3-4 inches below the central flower bud.

Remove all flowers or buds from your cuttings, then remove all leaves from the lower halves of the stems. Plant the cutting in potting soil, water it, then place it in sunlight or an artificial light of some type.

Keep in mind that you should do none of these things with plants that are patent protected. These are also good tips to help petunias bloom longer in the winter time.

The Lowest Temperature Petunias Can Tolerate

Petunias can only tolerate temperatures down to around 39 degrees Fahrenheit, which is well above freezing. They do best in daytime temperatures of 61-75 degrees and in nighttime temperatures of 57-65 degrees.

Here are some easy tips for growing better petunia plants.


Petunias can survive light frost if you take care of them. If you know that a heavy frost is coming, it is better to protect your petunias from the cold by either covering them or bringing them indoors to increase their odds of survival.

Frequently Asked Questions

What temperature is fatal for petunias?

Petunias are delicate, thin-leaved tropical plants that are usually grown as annuals due to their lack of hardiness. They thrive when nighttime temperatures are in the 55 to 65°F range, and daytime temperatures are between 61 and 80°F. When temperatures drop below 32°F, petunias are at risk of being damaged or killed by frost.

How can I protect petunias from frost?

There are several ways to protect your petunias from frost. One way is to use mulch, which insulates the soil and keeps the plants much warmer. You can also cover your petunias with blankets, tarps, or other temporary coverings. Make sure to water your petunias well before the first frost, as this can help them survive the cold.

Can petunias survive indoors during frost?

Petunias are not indoor plants and need sunlight to grow properly. While you can bring your petunias indoors during frost, they may not survive for long periods without proper sunlight. If you do bring them indoors, make sure to place them in a sunny location and water them regularly.

Do petunias return after winter?

Petunias are usually grown as annuals and do not return after winter. However, some petunias, such as the Wave series, are more cold-tolerant and may survive mild winters or return in the spring if they are protected from frost.

What is the temperature tolerance of wave petunias?

Wave petunias are more cold-tolerant than other varieties and can survive temperatures as low as 20°F. However, they still need protection from frost and should be covered or brought indoors during prolonged periods of cold weather.

How long do petunias last in pots?

Petunias can last for several months in pots if they are properly cared for. Make sure to water them regularly, fertilize them every two weeks, and deadhead them to encourage new growth. Petunias in pots may not survive frost and should be brought indoors or covered during cold weather.