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Overwintering Containerized Plants

When preparing your patio or deck for winter, don’t forget your containerized plants. Plants that have required common care during the warm growing season will need specialized care for the winter.

Plants that are hardy to USDA zone 3 or 4 should be able to survive the winter outside. As a precaution, though, I would move them to a location that is sheltered from the wind but gets a good amount of sun. You can do the same with plants hardy to our zone 5 or 6 but, as an extra layer of protection, wrap the containers in an insulating material like bubble wrap or Styrofoam insulation and place a layer of mulch around the container. Only the container stands between the plants’ roots and the freezing cold, and most container materials aren’t very good insulators.

Speaking of container material, many do not fare well in bitter cold weather. Terra cotta is one material that will break in freezing temperatures. Some ceramic and concrete materials will also break. These containers are usually manufactured in places where cold weather isn’t a problem. My personal preference is faux terra cotta made of heavy gauge plastic. Besides being weather safe, they are lighter to move around than the real stuff.

Inexpensive, portable, folding cold frame for overwinterting containerized plants.

You’ll have to make other arrangements for more tender plants. Those that are indoor plants just enjoying a summer vacation in the fresh outdoors, should be returned to their indoor home. Plants that can’t stand the extra cold that the winds bring should spend the winter under glass or transparent plastic sheeting. A greenhouse would be a perfect place for them but most suburban properties are too small for another structure. Instead, invest in a cold frame. Cold frames are available at garden centers, home centers and online in many different sizes and shapes using a variety of materials.

Wood and glass cold frames may be purchased in kit form or fully built. You can also build one from scrap lumber you have around the house and using an old storm door or windows to let the sunlight in. You can also purchase temporary, folding cold frames like the one pictured. If you have an annual bed that’s not being used for the winter, you can erect a temporary hoop house.

Super tender plants have to go inside for the winter. This doesn’t mean the garage, either. Most garages aren’t insulated or heated so they’re too cold for the plants. Few garages have enough windows to let in sufficient sunlight, and if the plants are sharing space with vehicles, they will be subjected to carbon monoxide and other pollutants.

If you have a three season room, also called a Florida room, that would likely work as a winter home for these plants. You might have to place a space heater out there to bring the temperature up to their liking. Be sure to follow the published safety precautions if you use a space heater.

No matter where you overwinter your containerized plants, they’re going to need some care. Outdoor plants would appreciate a drink of water whenever the temperature rises above freezing. Those stored inside should be watered on a regular schedule when they get dry, just as you do with houseplants. On a sunny day when the temperature is above freezing, it would be nice to open the cold frame and let them get some nice, fresh air.

One comment on “Overwintering Containerized Plants

  1. Terracotta and concrete insulate nicely from direct sun exposure though. Of course, that concern is now a few months away. I dislike most pots, but prefer terracotta when they are necessary. Fortunately, cold weather is not a problem here like sun exposure is.

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