How to Care for Container Plants in Cool Temps
Give your potted pals a place indoors to ride out winter together.
If you’re sad to part ways with the container plants you cared for all summer, there’s good news: Your relationship doesn’t need to end with the outdoor growing season. You can continue to dote on some of your leafy friends by bringing your plants inside for winter. Whether you let them go dormant or pop them in front of a sunny window, winterizing potted plants is pretty easy. Just make sure your new housemates are pest-free so you don’t end up snug as a bug—with actual bugs!
Here’s how to safely take your potted pals from the great outdoors to cozier confines inside.
1. Make a Plant-Moving Plan
Knowing when cold weather could kick in is the first, and perhaps most crucial, step in this mission. If your elephant’s ear accidentally encounters frost, you might be out of a plant. The other part of this process is knowing which plants to move and where they’ll go. Some will enjoy prime seating in front of a bright window while others would prefer a cool, dark basement where they can go dormant for the season, like a sort of botanical hibernation.
When To Bring Potted Plants Inside
Different provinces in Canada have different climates, so it’s good to know when cool temps are headed your way.
- Make sure you know when the average first day of frost is predicted for your region. That’s a clear indicator of when your plants need to be indoors. However, some varieties aren’t down with even the slightest nip in the air, so you may want to start the process once the night temperatures dip near 10°C.
- You’ll also want to leave some wiggle room—about a week—to work on acclimating your plants before they go inside (more on that below). Plan ahead!
Which Potted Plants to Move, and Where
Not all of your outdoor container plants are fit for indoor living without a big setup like the pros use (we’re lookin’ at you, tomatoes). While veggie plants don’t acclimate easily, not to worry—there are still plenty of leafy friends that can join you for a winter retreat. Take the time to plot out where each one is going based on their needs, and keep in mind that your transitional plants should be kept away from inside-only plants for several weeks, until you're certain there are no signs of pests.
- Near a bright window or under a grow light: Tender perennials (ferns), tropical plants (hibiscus), herbs, succulents, and certain annuals (geraniums, lantana, begonias)—plus, of course, any houseplants you moved outdoors for the summer.
- In a basement or cool, dark place: Tender bulbs—dahlias, elephant ears, calla lilies, caladiums—can go dormant. This just means you stop watering them and tuck them somewhere cool and dark.
2. Prepare Your Potted Plants
Now that you know where your plants are going to go, follow these steps to get them prepped for life inside.
Acclimate Your Plants
For one week, gradually reduce the amount of light your container plants receive by putting up a large umbrella or shade cloth, or by moving them into a shaded area for a longer amount of time each day. (Green thumbs will recognize this as the opposite approach to “hardening off” your plants.)
Check Your Plants for Pests
If you’ve ever seen a mama monkey meticulously groom her infant, that’s what you need to do to your plant right before you bring it inside.
- Get in there and examine every leaf, inspect the soil, and check the drainage holes for any signs of pests 3 days before moving day.
- Tackle any problems, but even if your plant seems pest-free it’s a good idea to gently wash the leaves and stems with a hose (some pests are tiny, after all).
- Let your plant dry, then spray it—soil and pot included—with an insecticidal soap.
- Wait 3 days, reapply the soap, and take your plant indoors.
- The first week or two, check on your plant often to make sure no hidden pests have popped up. If they have, put the plant in the tub, shower, or sink to give it a good rinse. Then, wipe the leaves down with a cloth and spray it with insecticidal soap. Further quarantine your plant and repeat this process weekly until the pests are gone.
3. Continue Caring for Your Plants
Once your botanical snowbirds are situated, you may notice the sunshine-lovers aren’t as perky as they were outside. That’s okay! Leaf drop and under-sized blooms are normal. Here’s the lowdown on how to keep these plants happy until you can get them back outdoors.
- For those in the sun, cut back on watering. Now that your plants aren’t sitting in summer sunshine, they don’t need as much H2O. Do a moisture check by sticking your finger at least 1 inch deep into the soil, and only water if it’s dry.
- Feed them as soon as you move them indoors, and then hold off for winter. Once plants show new growth in the spring you can bump it back up.
- Give plants a quarter turn each week so there’s an equal chance at light (helping it stay balanced, physically).
- If you decide to repot your plants, do so in early spring when the days are a little longer. This will give them time to settle into their new container before you move them back outside. (Make sure to feed after repotting!)
- After the last chance of frost has passed, you can acclimate your plants to life outdoors by letting them gradually spend more and more time in the elements.
For the container plants that go dormant for winter, all you need to do is check on them periodically and wipe their leaves if they appear dusty.
4. Clean and Store Your Containers
Transitioning containers is just part of winterizing the garden (if you also had an in-ground or raised bed this year, make sure to prep those for the off-season, too). Also use this time to clean up your containers and store any you won’t be using. This will help reduce pests and keep your pots from cracking in the cold.
- Store your soil. Pack any extra potting soil that’s still in bags, or used potting soil that you plant to keep, into an airtight tub somewhere dry.
- Clean your pots. Scrub all of your empty containers with a bleach-based solution to kill any disease or microorganisms. Clean any pots too large to move where they are, and if they’re empty cover the opening with plastic sheeting to prevent water from pooling and freezing (this can cause cracking).
- Protect your pots. Clay planters, like terracotta, are prone to breaking if they freeze. Turn these containers upside down and store them in the garage or another place that can protect them from the elements.
While it’s not quite as simple as picking up your potted plants and moving them inside, the process isn’t difficult. Plus, you get to keep warm and cozy with your botanical fam all winter long!