Acer winter protection

Ugo

Shohin
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Hi everyone,

I know this question has been asked many times but Im still unsure of the best method to protect my Acer Palmatum bloodgood for winter as I have done some "emergency" work on it.

I own this tree since a couple months only and I would like to ask members with more experience the correct method for keeping the tree alive and healthy during winter.
I think the first step in bonsai is keeping the tree alive so Im still on the learning curve with Acer.

I live in Québec, Canada region 5B, so normally the Acer bloodgood should require protection.
Winter can be hard here with low temp. for months and a lot of snow.
But in this case I had to repot the tree last week....
The tree was in organic soil, keeping a high level of moisture plus the soil was infested with ants.
I could see the tree was not as happy as it should be so I went ahead and did a barerooting repot.
The only thing I forgot is the extra protection it would require during the winter due to recent repotting....

While repotting everything was fine, to my surprise the roots were in good conditions and the ants didnt arm the tree roots and were probably looking for shelter only but it was impossible for me to know that before doing the repot.

The tree also suffer from bad wires scars on pretty much every branches.
Unfortunately the last owner didnt know better and left the wires on for a long period of time.

So here it is:

I think this tree will benefit from a frost free winter. Im I right?

The problem is, I have a couples places where I could put the tree but Im affraid I wont be able to control the temp correctly as we can see temps around -15 to -30degCelsius (5F to -22F) daily from December to March.

The options I have are the following:

-Home made winter shelter, insulated, but not air tight, protected from wind and sun with the pot burried in ground with mulch on top. This is where I place the spruce for winter so other trees can help protecting.

-Garage, Unheated , no insulation but I have access to electricity.

-Basement access, all in concrete, high celling with storm windows on 3 sides, not heated, possible access to electricity.

-An empty refrigerator....

If the tree doesnt need a frost free winter that would help me solve my problem but Im pretty sure it does...

If you have advises Im all hears!
Its the first time I found myself in this situation.

Thanks!

Screenshot_20210729-231953_Gallery.jpg
 

Dav4

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I can almost guarantee your basement will be too warm… Even temperatures in the low 40s Fahrenheit will end dormancy. I think your best bet would be your garage with the tree placed on a heat mat set just above freezing. Either that, or you could look into building a cold frame, though there is no guarantee that the roots would not freeze there, Though I’m not sure how important keeping the roots from freezing really is since you still have another three months before dormancy arrives.
 

Jimmers2

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I enjoyed reading about your concern and possible solutions for the season challenge ahead, Ugo.
I have a 8" pot of first year seedlings that I need to protect as well, and located west of Grand Rapids near the Big Lake it can get very cold, but not as cold as Qc.
I am new to bonsai and my plan is to use the patio when the weather allows and go to the garage, with some type of heat source, when the temps get close to 0F.
Condo living has its limits but also freedoms.
Happy cultivating my friend,
Jim
 
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papkey5

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Trees will grow more roots in the warm months of autumn before winter sets in. Your Acer will also need a full dormancy.

My advice:
Keep the tree well watered for this growing season. Water will insulate the roots so keep the soil moist, not soaked during winter.

I would bury the pot and cover with mulch. I had done that with some seedlings last winter and they survived. Roots will survive being frozen so long as they don’t freeze then thaw and freeze etc. that is what will kill it.

do not put it in the garage. It will be too drafty and cold, even if placed on a heat mat. The draft will dry out the soil and roots and that is what kills trees.


where do you plan on having the empty fridge?
 

Dav4

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Trees will grow more roots in the warm months of autumn before winter sets in. Your Acer will also need a full dormancy.

My advice:
Keep the tree well watered for this growing season. Water will insulate the roots so keep the soil moist, not soaked during winter.

I would bury the pot and cover with mulch. I had done that with some seedlings last winter and they survived. Roots will survive being frozen so long as they don’t freeze then thaw and freeze etc. that is what will kill it.

do not put it in the garage. It will be too drafty and cold, even if placed on a heat mat. The draft will dry out the soil and roots and that is what kills trees.


where do you plan on having the empty fridge?
I overwintered many different trees in my unattached, unheated and uninsulated garage in zone 6a MA for over a decade back when it atually got cold in the NE and stayed that way all winter... mulched on the cement slab floor... never lost a tree or even suffered a setback except for some damage from mice. The biggest issue using outbuildings as winter storage is actually heat gain starting in mid winter as the sun gets higher in the sky. You actually want the trees to get cold and stay that way. Otherwise, the trees will be breaking dormancy in mid February, or over 2 months too early. Mulch the pots with wood chips, water well and you won't need to water more then once or twice more until spring. Personally, I wouldn't bother with the heat mat and would just mulch well on the garage floor, but the OP wanted options and the heat mat will work, mulched or unmulched. He just needs to water more frequently.
 
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LanceMac10

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Garage will be fine. We don't even mulch-up. In fact, have several JM's I just throw on racks on the porch....as mentioned however, things get "cooking" really early.
 

hinmo24t

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I overwintered many different trees in my unattached, unheated and uninsulated garage in zone 6a MA for over a decade back when it atually got cold in the NE and stayed that way all winter... mulched on the cement slab floor... never lost a tree or even suffered a setback except for some damage from mice. The biggest issue using outbuildings as winter storage is actually heat gain starting in mid winter as the sun gets higher in the sky. You actually want the trees to get cold and stay that way. Otherwise, the trees will be breaking dormancy in mid February, or over 2 months too early. Mulch the pots with wood chips, water well and you won't need to water more then once or twice more until spring. Personally, I wouldn't bother with the heat mat and would just mulch well on the garage floor, but the OP wanted options and the heat mat will work, mulched or unmulched. He just needs to water more frequently.
great advice. im in MA, and overwintered in cold garage with many plants.
i left maples against back of garage and they lived outside but i have some more 'tender' ones im going
to do what @Dav4 said, in garage and im adding woodchips on my trays with small maples.

he was correct it only takes one or two waterings for the entire winter for them (small pots for me i might mist them once a week or every other) you dont want still air and a lot of water for fungus mold bacteria etc so i will have my doors open to encourage
draft or a ceiling fan in there sometimes on weekends, etc. or after i mist

i think the garage is +10* compared to outside and i think it is 40* in there sometimes, havent noticed any dormancy break on
other trees ive done it with, and i run a kerosene heated a few times a winter when im wrenching in there, getting temps up to 50*

its pretty dark in there which doesnt hurt keep it wintered.


so outside protected from wind and buried in or mulches, or cold storage
 

Ugo

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where do you plan on having the empty fridge?
In my heated basement!
But Ive read to many horror stories so I think I will forget this possibility.

@Dav4 Thanks for the information.
I dont know if it change anything but the ceiling in my garage is quite high and with a proper fan setup I think I could keep the hot air up top.
 
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Ugo

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@Jimmers2 Jim, thanks wish you good luck for the coming winter! Reading more comments you might want to reconsider using a heater.. Hard to decide when you have no experience but everyone seems succesfull with their own method so we will find ours!

@Dav4
Do you think keeping lower temps until March could be achived?
Just to put things in perspective the month of February here is quite cold, the highest temperature will be around 23F, coldest during night time is around 10F outside.
Maybe it can change timing a little.
Its something I will have to test but with basic infos such as temp and humidity in/out I should be able to maintain "constant" temp atleast until March.
You gave me very good guidelines thanks again.
 

Dav4

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@Jimmers2 Jim, thanks wish you good luck for the coming winter! Reading more comments you might want to reconsider using a heater.. Hard to decide when you have no experience but everyone seems succesfull with their own method so we will find ours!

@Dav4
Do you think keeping lower temps until March could be achived?
Just to put things in perspective the month of February here is quite cold, the highest temperature will be around 23F, coldest during night time is around 10F outside.
Maybe it can change timing a little.
Its something I will have to test but with basic infos such as temp and humidity in/out I should be able to maintain "constant" temp atleast until March.
You gave me very good guidelines thanks again.
The key is ventilation and wetting the mulched down well and letting it freeze. I monitored the root temperatures and the air temperatures above the mulched pots using an indoor/outdoor thermometer. The roots always stayed around 32 F/0 C through the winter but the air temps could fall into the single digits F. Still, once mid February came, even though it was still below freezing every night and during much of the day, the sun on the garage roof started heating things up inside. Leaving the doors open, +/- a fan, helped move warmer air out during the day... and there were times the doors were open at night and closed during the day if it was cloudy. For me, the mulch stayed frozen most years well into March and even April depending. If you do this, make sure you set up mice traps or have other means of protecting your maples from mice and voles... they love maple bark and can do quite a bit of damage unnoticed in a garage.
 

LanceMac10

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I've got three JM's in grow boxes that I threw on the ground spring 2020. They ended up throwing roots thru the bottom and into the ground. They remained in the same spot thru till today and beyond. No mulch. Did fine and actually awoke when they were ready; April. If you mulch, in the garage or outside, try to time it around the time that it'll freeze quick. Not too early else some critter might take up shop in your mulch pile.

As mentioned, when spring is approaching, you need to be mindful of temperatures in your storage area. Keep as cool as you can for as long as you can.
 

leatherback

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How long before frost hits? If you have another 6+ weeks, don't worry about it. Just protect as normal. The tree will re-establish itself in the weeks to come. Late summer repotting is recommended by a number of well-known bonsai artists. I find my maples do not skip a beat.
 

Ugo

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How long before frost hits? If you have another 6+ weeks, don't worry about it. Just protect as normal. The tree will re-establish itself in the weeks to come. Late summer repotting is recommended by a number of well-known bonsai artists. I find my maples do not skip a beat.
Hi!

First frost usually happen in the beginning of October.
That give me about 7 to 8 weeks.
So far the tree seems to react correctly to the repot.
It will be my first winter with the tree, I dont want to baby it too much but at same time Im a little bit nervous as I dont want to do mistakes with my only maple!

My original plan was to place it with my spruce, in the ground with pot covered with mulch,leafs and snow.
This space is covered with a hard top and insulated walls around except for 1 side that is covered by a tarp.
The garage is also a good place but as other members have said rising temperature inside the room too early in spring make's me doubt.

The good thing is I still have a few weeks to think about the best option!
 

Cosmos

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Ugo, for a few dollars, you can have your tree (or a few trees) overwintered at either Bonsai ENR (St-Joachim-de-Shefford), Art et Culture Bonsai (Shawinigan-Sud) or Bonsai Gros-Bec (St-Alphonse-Rodriguez). A good opportunity to encourage our bonsai economy, build a relationship with the people who run these businesses too (but the best part is you can visit during the winter and marvel at the spectacular clients’ trees spending the cold season there, esp. at Les Bonsai ENR) and not having to worry about the cold. This is what I’d do for your maple.

Your spruce needs little protection, just outside on the ground, with mulch, protected from dominant winds should be just fine.
 

Hack Yeah!

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garage is quite high and with a proper fan setup I think I could keep the hot air up top.
[/QUOTE]

I'm not certain if you're referring to venting to the outside? But you don't need a fan to keep the hot air up top, if anything a fan will move hot air down
 

Ugo

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Ugo, for a few dollars, you can have your tree (or a few trees) overwintered at either Bonsai ENR (St-Joachim-de-Shefford), Art et Culture Bonsai (Shawinigan-Sud) or Bonsai Gros-Bec (St-Alphonse-Rodriguez). A good opportunity to encourage our bonsai economy, build a relationship with the people who run these businesses too (but the best part is you can visit during the winter and marvel at the spectacular clients’ trees spending the cold season there, esp. at Les Bonsai ENR) and not having to worry about the cold. This is what I’d do for your maple.

Your spruce needs little protection, just outside on the ground, with mulch, protected from dominant winds should be just fine.

Hi!

Great to see another member from Qc.
I must admit I didnt even think about the option!
Im a little bit shy bringing the tree to pros as its a work in progress but I might get some advises and good conversations while Im there!
I will give a call to bonsai ENR just to see the conditions and pricing.

@Hack Yeah!
I should have been nore precise..
Yes the fan would vent the air outside.
The garage has venting on top but no fan to push the air out.
 

Ugo

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Hi everyone,

Just to give a quick update!

I decided to build a cold frame without windows so it is more like a big cooler to protect the trees from snow, heavy wind and frost while being insulated enought to keep the temperature from dropping too low in Winter or getting to high too early in the Spring.
I've been quite busy theses days building it.
Its nothing fancy for sure but its at the other end of the yard and Im pretty sure it will do the job despite its look.

I still have to insulate the top and keep a gap between insulation all around the top of about 1/8 to allow air mouvement.
Plus digging and installating a temp. Sensor to monitor pot temps vs outside and humidity.
I will also add rodent protection all around the base on the inside just in case.

The trees will be buried in 6in to 8in of mulch then covered with snow when time comes.
I was thinking about digging up to 12-15in and add gravel at the bottom of the hole as a drainage layer, cover the gravel with mulch put the trees in and cover.

Box open
20210907_191207.jpg

With safety beam to support the weight of snow.
20210907_191308.jpg

Top closed
20210907_191337.jpg

Missing the Foam insulation here.
It will covert this area leaving a 90deg angle of 1/8 gap to allow air movement.
20210907_191343.jpg

Im actually thinking if I should cover with a white tarp or not.
If I dont cover it there will be more water infiltration from snow melting maybe too much...
While if I put a tarp I reduce the water infiltration but I will have to water the trees and depending on the amount of snow-ice on top opening the cold frame could be a little challenging.

Thanks
Ugo
 
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Forsoothe!

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Snow is a poor conductor, so anything buried in snow will stay some temperature it was when the snow covered it. That's good and bad. The good is the temp's can stay in the mid -5°C range if you have snow cover early, and that's good because the temp of roots of JM need to stay above -10. The wood can take most anything with the caveat that drying winds take their toll over time. The bad is the pot will need to be watered every 3 to 4 weeks and snowed-shut then becomes problematic. If you can leave it open and fill it with snow that should last, except snowload can break a lot of branches. Not just the snow, but the melting/refreezing snow changes in character. It melts from the top down into lower layers of snow which increases the density and therefore the weight of the now ice which can break the branches. So there is no magic answer, just different problems. just getting to the box can also be problematic when the snow is deep and you absolutely need to water. Been there, done that.

The garage thing also is a double-edged sword. Good protection as long as it stays between +2 and -6 to keep the tree dormant and the roots not too cold. Watering via snow on the frozen soil works nicely and you can see whether or not it is dry. You don't want the rootball to be sodden when it freezes, as ice damages JM roots. The bad part comes in spring when temps increase in the daytime garage. When the quiescent period has been satisfied and the temps are above +6 the tree will begin to leaf out. That's always before it's warm enough to put the tree outside overnight. So, you do the bonsai two-step of out on warm days and back in overnight. Also, the leaves will crispy-ize if you go from inside to out in sun, so you add to the two-step, inside to outside in bright shade for the first couple weeks.

Outside of that, nothing to it.
 

Canada Bonsai

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@Ugo I would bring your tree to Yves (Bonsai ENR) or Art et Culture. The overwintering fee is about $10-30 per square foot per winter, and you know it will be well cared for. At these locations you will also run into other hobbyists who can provide good advice in general and about your tree. Both locations sell Japanese maple cultivars that are appropriate for bonsai, and this has been Yves' specialty for 40 years. It will be formative to view your maple alongside these other cultivars to compare and contrast their characteristics.

In Quebec (and I'm sure the situation is the same elsewhere), everybody knows somebody who has lost trees due to rodents while overwintering in a shelter like the one you are building. Some of our best local senior bonsaists with 30+ years experience and apprenticeships in Japan lost a combined 60 very old, mature, beautiful trees last year -- what I mean to say is, nobody is immune to this when creating a shelter like the one you are building.

As your collection grows, you may want to consider one of these: https://cdn.shopify.com/s/files/1/0...-e14a-498b-80d4-b7ff69d95b45.pdf?v=1603896022
 

Forsoothe!

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Yeah, I forgot to mention that you need to include mouse food;)in any enclosure because mice will find a way in, and they'll get hungry. They can eat your trees, of which JM are a favorite, or they can take the bait, your choice.
 
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