Freezing temperatures, gusty winds, and dry winter conditions can adversely affect your outdoor potted plants. That’s why overwintering your container plants is vital if you want to keep growing the same plants year after year.
Not all potted plants last for multiple years, but many species we grow as annuals are actually perennials in warmer climates. True annuals will die back at the end of the growing season, but a perennial container garden can thrive for multiple seasons if you winterize plants the right way.
As long as your potted perennials are hardy in your growing season, they can survive the winter and regrow in spring. But proper container gardening winter care is important for hardy plants, too. The roots in a pot can get as cold as the surrounding air, so some protection is usually necessary.
If you don’t overwinter plants, they may not survive until spring. I’ll share some expert tips to help you provide protection for your container plants in winter so they return in spring.
Is Overwintering Container Plants Necessary?
Container plantings provide dimension and texture to your outdoor living space, but most plants need some extra help to withstand freezing winter temperatures. The hardier the plant, the less winter care it needs. However, all potted plants should receive some protection. Being in a pot makes plants more vulnerable to cold temperatures.
Overwintering plants in containers is important because there is not much buffer between the roots and the outdoor temperatures. That means roots are more sensitive to cold than those planted in the ground. Ideally, the plants you keep in containers over winter should be hardy to one or two USDA growing zones colder than your own.
The type of container also impacts a plant’s chances of survival. For example, smaller containers get colder faster and terracotta pots are more likely to absorb moisture throughout winter. Consider these factors when overwintering plants in containers.
How to Overwinter Container Plants
Start making overwintering plans well before the first expected frost in fall. For plants that are deciduous or die back, cut foliage back to the crown. Then follow the below strategies for overwintering container plants to give them the best chance of surviving the cold season.
1. Move Containers Inside
The most obvious way to keep dormant container plants warm is to move them indoors. Moving several pots with dormant plants into the house may not be practical, though. If you’re lacking indoor space for all your potted plants, a garage, unheated greenhouse, hoop house, or mini shed are all good options.
Make moving potted plants easier with a plant caddy, like this 2-pack from Amazon. Container plants can be extremely heavy, especially large ones. So rolling plants indoors is a great way to save yourself some effort and protect your back.
2. Wrap and Cover Pots
Some plants do fine without a cover, but to protect plants from hard freezes, you may want to have a clear tarp available to tent over tender plants that are not inside some support structure. If you only have a colored tarp, make sure to uncover the plant during the warmest part of the day every couple of days to get light.
You can also wrap pots with plastic. Bubble wrap works particularly well to keep plants’ roots insulated. You can get bubble wrap in bulk from Amazon.
Another good option is wrap your plants in burlap. It’s not as insulating as bubble wrap, but it’s more sustainable. Plus, you can reuse the burlap in a variety of ways in your garden next spring and summer.
3. Group Containers Together
If your winters are not too cold, protecting plants can be as simple as grouping them together in a sheltered outdoor location. Cluster pots together with the smallest on the center under an overhang, hedge, or other protected area.
Wrap the group or cover with burlap, if temperatures are extremely low. Burlap is available on Amazon as well as from most garden centers.
4. Put Pots in the Ground
Plants in the ground fare better in winter because the roots stay warmer. They’re not exposed to the dramatic swings in air temperature because the soil takes longer to change temperature. This helps insulate potted plants and protect roots.
You can dig holes in the ground and place pots in them to keep them warm throughout winter. After sinking pots in the ground, cover the area around each plant with an organic mulch, like this one from Back to the Roots, for extra protection. Or you can use your leftover leaves from fall cleanup to add insulation. Pull the mulch away from plants in early spring so new shoots can receive necessary sunlight.
5. Water Potted Plants
Finally, it’s important to water potted plants before winter sets in. Moist soil stays warmer longer and reduces stress on the plant. When you water plants before a freeze, it actually gives off heat since water only exists at temperatures above freezing. This can help protect plant roots.
However, overwatering can cause pots to crack in the cold due to water expanding as it freezes and ice forms. Excessively wet plants also have a tendency to rot in confined spaces with too little drainage.
Ensure plants are in containers with drainage holes and a well-draining potting mix. Remove any fallen leaves from the surface of the soil to prevent fungal issues, like botrytis, which can overwinter on foliage.
What to Do in Spring
In spring, your container plants will be ready to come out of dormancy and start growing again. Check for new growth to determine when to start uncovering and moving potted plants in spring. Timing will vary depending on your location, but it’s important to wait until after the risk of freezing temperatures and your local last frost date.
Slowly ease them out of their protective areas or covers. This will allow them to acclimatize better. For example, if you keep pots indoors, move them outside with a plastic cover or to a sheltered spot first. Let plants harden off a little before separating the pots and placing them in their usual locations.
Frequently Asked Questions
Can You Leave Potted Plants Out in Winter?
Yes, you can leave hardy potted plants outdoors in winter with the appropriate protection. Wrap pots in bubble wrap to prevent them from absorbing water after the plants have gone dormant. Wrap container evergreens after the first frost.
Should You Water Container Plants Before A Freeze?
If you live in a warmer climate but are expecting a freeze, water container plants ahead of the cold snap. This will help keep the plant a little warmer and also reduces stress, which minimizes cold damage.
