Wintering in Wyoming - de-icing cables or heat tape?

Hello. I’m new to Mirai and a novice to Bonsai. I began some young bonsai from nursery stock in southern Utah a few years ago before moving to Wyoming. Winters where I’m at routinely get well below zero at nights and below freezing during the day. Sadly all of my original trees have gradually died, worsening after each winter. I’ve tried a make-shift greenhouse with a heater (that died mid-winter), cold frames with the trees buried up to lowest branches in mulch, and the same without the cold frame. My observation is that the roots eventually fully or partially freeze.

I have 5 new young trees that survived our July hail storm and I’m hoping to develop and keep alive through the winter. I have a Rocky Mountain Juniper, Ponderosa, Blue Spruce, and 2 Black Hills Spruces. Each is in training pot that could be planted in the ground.

Has anyone had success with simply planting the pots but with de-icing cable (like used for roofs/gutters) under or around the base of the pots? Such de-icing cables are cheaper to power throughout the winter than a heater in a greenhouse, and I know longer have a greenhouse or cold frame. Any other ideas are welcome too!! I feel with what I know and will learn through Mirai I can produce some decent bonsai but I keep getting stopped by winters.


Find a friend with a coldframe/greenhouse and rent space.
Winds are often the culprit. You may be thinking cold, but winds cause desiccation and have killed many trees here in Colorado. Put up a wind break.
You should talk to and ask Backcountry Dan, he’s up your way and has learned a lot.
Your trees need to be healthy to make it through winter. Did you do any big pruning or work 6 or less weeks before the first freeze? Did you fertilize a lot in the fall per Ryan’s advice? Fall fertilization keeps trees alive in the winter. Last idea I have is, did your trees grow enough during the year to have enough solar panels to accumulate the growth necessary to store energy for the winter?

And sorry, I’ve not heard of anyone doing what you actually asked about. But I think some ideas here may be helpful. Good luck!


Thanks for the reply. I’ll reach out to Backcountry Dan. Despite a hail storm that damaged my trees heavily, they’re showing good growth including back budding since. I’ve been following Ryan’s recommendation on fertilizing for development and won’t be doing any pruning or wiring the rest of the year. I’ll have to incorporate some wind breaks somehow - winds are an issue for sure. Thanks for the tip.

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Hello Craig,

I just saw your message. Thanks for getting in touch.
All of the species you mentioned should be good to go in our climate, though I’m sure your winters are bit colder and involve more snow than mine. (I’m in Douglas)

As Eric said, wind is more likely to kill your trees than the cold. I have not used any form of extra heat to date. I will be putting together a heat bed for weak or recently collected trees, but for anything that is established and healthy I will either pack the trees in as close together as possible near my on the east side of a fence or other structure, and then mulch around the pots. But I wouldn’t mulch above the rim of the pot to allow air flow. Other club members here sink their trees in to a gravel bed for the winter. Both approaches seem to work well. Other trees we winter in a cold garage or cold frame if there’s space, just for added security.

A lot of factors play in to winter survival, but the health of the trees going into winter is paramount. Then wind protection and protecting the root zone from extreme temperature fluctuations. (Many of our trees freeze solid nearly all winter.) It’s also good to keep any eye on the pots to make sure nothing dries all the way out during a warm spell.

If you haven’t, I’d recommend watching these streams for a good handle on wintering:


Thanks @BackcountryDan! I’ll watch those videos. And thanks for the other tips. Where my trees took some hail damage I may opt for a cold frame. Its good to know additional heat may not or should not be needed. Are you a member of a local or state bonsai association?


I’m in north eastern Wa state. Your probably colder than here. I have typical 20Fwinters, and sometimes -15F for a week here. I’ve been successful here for 22 years with a lean-to/ windbrake made of cinder blocks (my bench material) on the side of my garage. The 8’ 2x4s go over top for snow load-- with a tarp thrown over and secured with more 2x4s, below 20F. Several members here use underground / poly hoop storage ( a coldframe). Never heated or used a greenhoused for my trees. I dont do Tropicals. On purpose… last winters pot temp minimum was 24F. Everyone survived, and thrived.
My Utah oaks I moved here with slowly dyed. Replaced with local (Q. gambelii or robar ?) acorns … The only other tree I can say probably succombed to winter here was a bald cypress. Just acquired another last fal!
Your Tree choices will do OK there. Root freezing probably WONT kill them. The heater idea seems good, but then the tops freeze hard… Still need wind protection.

I co-own and operate Backcountry Bonsai, and we have a small club here: the Laramie Peak Bonsai Society. We meet for lunch about once a month (very informal), and will often visit each other’s yards afterwards. We also bring in quite a few professionals for club workshops and/or private work for Backcountry. We’ve had Todd Schlafer, Ryan Neil, Bjorn Bjorholm, Matt Reel, Tyler Sherrod, Owen Reich and Jerry Meislik. Todd will be here again next weekend; you’re welcome to join or observe if you happen to be free and want to make the trek.

The only other club I’m aware of in WY is the Cheyenne Bonsai Club. They meet once a month and plan occasional workshops and a show in late September at the Cheyenne Botanic Gardens. We jump in with them for an event now and then.

Several of us are also part of the Rocky Mountain Bonsai Society based out of Denver. The 50th annual show is coming up September 7-8 at the Denver Botanic Gardens. I and two of our other LPBS members are entering trees.

We also got some hail this spring, and then again last week! :frowning:

those species can be wintered outdoors in WI so I suspect WY also. use a grow box and bury them in straw up to their foliage so they stay cold. you need them to stay cold once they get cold. put a fence around them to keep deer out. that is all we do with those species. otherwise you need a cold building kept at 37 to 40 during the winter. the outdoor trees are actually the easiest to winter as they don’t need anything. I suspect you didn’t have trees that could handle it or they went through freeze thaw during the winter.

Follow up question for those in high elevations, near or in the Wyoming region: When (based on month or temperatures) do you move your trees from display to their winter “homes”?

The weather patterns have been way too odd the last several years. I watch my trees and the weather channels. We have had early 25F December weeks and THEN 50F weeks.
MOST ( if not all) of my trees will take overnight 30F. Ok. Snow is fine…nock the snow off slender trees.The tropicals go in at overnight +45.
I DO NOT get worried untill the first HARD FREEZE. Well after leaf fall. (The only trees I have lost to obvious winter kill were a black pine and horse chestnut I took into a garage…)
I start preparing winter storage and slowly move the herd that direction. Decideous first. Pines last. Some stay out untill 20F days. I hate to do it ALL in one cold day…
Oh ya… do not forget the mice poison in covered cups with small holes…
Read: Winter Care below 20deg F
And: Winter Storage Concerns
Hope this helps. I wish I had Mirai 40 years ago! All I had was the 1960’s Sunset Magazine book.
Enjoy… Bonsai on! (Haute Bonsai!)

The first sub 28 deg F nights are coming up Wed/Thur this next week here. Then low 30’s at night after that with highs in 50-60’s likely for a few more weeks after that. I plan to place my trees on the ground hilled-in with mulch for this initial freeze until I get something more long-term built.

Here’s my initial idea for long term wintering based on the videos and forum threads I’ve read - I welcome everyone’s feedback…

Basically, I’m thinking a combination of a heat bed with de-icing cables, and a cold frame, next to the south side of the house. I may use the pumice layer like shown in the videos but will hill them in with mulch to edge of the pot, maintaining clear surface of soil inside the pots. I’m concerned about the temperature swings that occur here, and would like to allow snow to get onto the trees to help with watering, so I’m considering NOT using a roof (or at least only closing it if temps get extremely cold) so I don’t get temps above 40 inside unless that’s the outside temp. Unlike the warming cables shown in the videos, the de-icing cables won’t get the root level warmer than a little above freezing but I think my young recently hail-damaged trees need some extra help. I’m thinking of using transparent materials for at least the top halves of the sides and top for the cold frame to allow sun light.

Have any of you tried using a double layer roof like Neil talks about in the winter prep video? I’m curious if that would control temps sufficiently to leave my cold frame top closed down.

Have you tried a combination of heat bed and cold frame similar to my idea?

Oh, and any advise on ratio of mulch, etc. there should be for hilling them in?

Here’s what I ended up with: pots on ground, in open-top cold frame (made with materials I had around) so I can add snow if needed, hilled in with mulch, with de-icing cable under pots set to turn on when air temps drop below 28. I’ll make a follow-up in the spring when I know how they did.

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Nice solution!!!

Question, how did you get that nice moss to grow? I am in Colorado and it dries out and dies on me.

Honestly, I just transplanted this moss from a local source a few weeks ago. So far the location of their winter beds has allowed it to stay well so far. Wish I had some good advise for you - its the first time I’ve used a top dressing.