Winter Care below 20deg F

Richard, 2nd winter with trees in Chicago, but with many more this winter. Only option is unheated and deattached garage. I have metal shelves and plan on boxes/containers with mulch surrounding the pots. Did you have any issues with mice? Either way did you utilize mice bait? Any specifics greatly appreciated…

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I put out decon in covered styrefoam soup cups, every three feet inside the covered area. Also at corners outside. . Cut a mouse sized hole in the lip… Still had several trees chewed last winter. The bait is always gone.

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Sorry not to have responded sooner; been a crazy week at work which carried through to the weekend.

Sounds like you are taking the right precautions for the trees with mulch. Would add one suggestion to provide a bit of warmth on the coldest of winter days: I take two large beach towells and drape them over the trees on my mobile rack. Keeps the draft out top to bottom. Have never used heating pads despite the fact that temps get down to around 20 degrees when it’s below zero outside.

About mice: My situation is different yours. My unheated garage is ATTACHED to my house, not a separate structure. We rarely have a problem with mice so it’s hard to provide suggestions based upon personal experience. I have not had any issues with mice chewing trees and have not placed traps or bait anywhere inside my garage.

That said, there are many ways you can address/eliminate a rodent problem, most of which you likely know about or can look up, but it’s definitely more difficult eradicating the problem in a detached garage.

Let me know if you have questions about prepping the trees for dormancy; happy to share what I do and have done for the last 12+ years. Good luck.


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Huge thanks Richard! No worries on a delay. :grinning:. I really appreciate suggestion to further protect trees when we get single digit temps in Jan/Feb. — I’ll definitely prep for that. Please, I’d also appreciate any tips for winter prepping prior to dormancy — especially around Shimpaku’s and Hinoki’s. This will be the first full winter with trees. The few trees I started with went into the garage mid-late January. Thanks again Richard…

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Prior to dormancy: Don’t baby your trees. Other than tropicals, most trees can tolerate a light frost. As fall transitions to pre-winter, keep a watchful eye on predicted nighttime temperatures. Try to keep the trees outside as long as possible, which for me in northern Vermont means until mid-late November. If a sharp drop in temperature/hard frost is predicted, I place the trees in my garage overnight and pull them out once temps hit 38-39 in the morning. I continue in this vain until one day in late November I decide they are ready to stay in the garage until spring. Best guess, nothing more.

Storage through winter we’ve discussed.

Here’s how I approach the transition on the other end (winter to spring): I gradually reintroduce the trees to the outdoors as spring arrives (early April in Vermont) by wheeling them outside (temperature permitting) for about 4-5 hours/day each afternoon…and placing them back into the garage each evening. Outdoor hours are increased weekly, until the final frost around the 3rd week in May. After that, they remain outside 24/7.

Best of luck with this year’s transition. -Richard


Richard! I really do appreciate your feedback. I’m thinking we may not be too far off with temps/timing. Our midnight to 5 am temps of recent have been 29 F for 2-4 hours. All trees still outside. One question- Do I treat Evergreens (Shimpaku, Hinoki) the same as Decidious? I’m assuming so (?) Much thanks and best wishes with the upcoming Holidays…

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That depends on what deciduous species you are over wintering. The root sensitivity is most important according to Michael Hagedorn. A table that gives average temperature for killing plant roots is below. Table 1. Average killing temperatures for roots of selected species of woody ornamental plants. Euonymus is more cold hardy than maple. Learn lots. Share with others. Have fun.