GROWING THINGS: Tucking in for the temperature drop

Plus, gardening above tree roots

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Q We have planted three beautiful cedars in pots to divide our outdoor kitchen from the outdoor living room. We enjoyed them all summer long. With winter right around the corner, we keep wondering, what can we do in order for them to survive the winter?

A Ahhh, yes, the age-old question … how to get potted plants to survive the Alberta winter. Plants that are growing in the ground have a better chance of surviving than any containerized plant. Even plants that are hardy for our area will have a hard time making it through the winter in a container. The reason for this is that in a container the roots are subjected to freeze-thaw cycles that will damage the cells in the roots. Plants in the ground have their roots protected and insulated much better from these temperature variations.

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If you want to overwinter containerized plants you will need to protect the container with an insulator such as home insulation and the more the better. Wrap the pot with the insulation and make sure you insulate the bottom as well. The insulation will help protect against the freezing and thawing. An unheated garage is a great place to overwinter containerized plants as it keeps the wind off the plant. If you don’t have a garage and are forced to try and overwinter the plant outdoors I’d recommend keeping the plant in more of a shady location. Placing it out in the sun increases the chances of thawing and freezing.

Another problem with trying to overwinter containers is the moisture factor. The soil should have some moisture in it to keep the roots from drying out completely and yet too much moisture can create problems with ceramic or terra cotta pots. The expansion as the water freezes can crack non-plastic containers and even some plastic ones.

I know of gardeners who successfully overwinter many plants such as Japanese maples and other sensitive plants but they put in a lot of time and effort to ensure the plant’s survival. Overwintering containerized plants is at best a gamble but you can improve the odds considerably if you are prepared to do the work.  

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Q We created a new garden on our lot five years ago. We trucked in a lot of good soil at that time. Each successive year I find tree roots are taking over to the point I can barely dig potatoes and this year has been the worst. There is a mixed stand of trees three metres from the narrow end of the plot which I’m sure is the source of my problem. I’m thinking of skipping the garden for a year and do heavy and frequent rototilling. Do you think that would help? I’m not keen on relocating the garden.

A Tree roots can be an issue in many beds but this problem in a vegetable garden may be the worst. I’m afraid there is little that can be done to solve the problem. Heavy rototilling will result in severe damage to the roots and may, and likely will, cause the demise of some of the trees. One thing to consider is making the garden into a raised bed style. You can construct simple square frames from 2×6 lumber, fill the frames with soil and garden above the roots. This is a solution that has been used successfully for many years in gardens that have tree root problems. If the garden area is a large one you can construct several smaller frames rather than one large one.

Alberta Urban Garden has a great website that talks about raised beds — Raised Bed Gardening Beginners Guide.

Every week, Growing Things Outdoors runs online at or, if you prefer an epaper format,

Learn more by emailing your questions to [email protected], reading past columns at or my book, Just Ask Jerry. You can also follow me on X/Twitter @justaskjerry01.


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