Winter care Maple

[xray]

Hi bonsai friends!

I started this year with bonsai and I have yet to conqueror a winter with my trees so I would like some advice.
As it should say in my profile I'm from Sweden living in Zone 5a, so pretty rough winters here.

I have a few indoor trees like some ficus benjamina and a Chinese elm that is outside during summer and I will try to have it inside during winter months.
But for outdoor i have some native pines (Pinus sylvestris) and Japanese Maple (Atropurpureum)

I live in a house with a big backyard, unheated garage and a unheated glazed terrace.
But the glazed terrace should be much warmer because it takes passive heating from inside I guess...
Or do I dig a hole and put them in the ground covered with mulch?

1. Put the trees in the unheated garage
2. Dig a hole and put them in the ground, protected from wind.
3. On the glazed terrace.

 

[Tinyjames]

I think you just have to place / protect them out of the wind

would you lift all the trees around you and put them in a unheated garage ? I think you do more harm than good protecting them to much they are trees at the end of the day But like you i.m a beginner so what do I know

 

[RoadManDenDron]

Way outside of my climate experience but Google says they can survive in zone 5 or up to -28 C in the ground, it can be more of a struggle in a pot so you could be right on the edge of what it can take. More local or other cold zone members may have better advice...

In theory, the key is experiencing a proper autumn which allows the tree to acclimatise and prepare for the cold weather.

Also need to be careful in the spring of any frosts after it starts to wake up.

Above is for the maple BTW I imagine pine will be fine

 

[pandacular]

Not really what your question is about, but I would take extra care with wintering an elm inside. I believe their sub-tropical attributes make it possible, unlike a maple, but they probably need more care than a sunny window, unlike the ficus. I'd get a grow light for both of those, and look into their humidity and air flow needs.

 

[Aphystic]

I have a Japanese maple on my balcony but it’s a “real” tree and not a bonsai refined tree. It however just sit in its pot all winter and has no problem whatsoever. I think it’s good to just put the pot alongside the tree in a box of wood mulch or such and it shouldn’t be much of a problem.

 

[SgtPilko]

Feels like either of the unheated indoor spaces could work? So long as the glazed one doesn't get too warm in the sunshine. The dormant trees won't need light, just a bit of water infrequently.

Here in the UK ordinarily maples are fine outdoors, but just as a warning we have seen a lot of good trees suffer this past year with a super hot summer (40 degrees Celsius at times) followed by a very freezing winter where the pots were frozen solid for extended periods. When struggling trees were investigated they had LOADS of dead roots and need to be repotted and nursed back to health. Shallow pots and temp extremes don't mix too well.

 

[dbonsaiw]

I'm in 7B, but like to keep my trees outside over the winter, either buried in the ground or in mulch.

 

[xray]

I also think it can be difficult to handle the temperatures in a glazed terrace like you said @SgtPilko
Putting them in my garage might be the best solution but I'm still concern that roots will be freezing in my garage when it's -30c (-22f) outside for a long time. The garage is not well isolated, but I guess the trees will be safe from the wind.

 

[SgtPilko]

Yikes -30... Maybe get into native species? nah but i think they'll be alright, you can insulate them a bit more round the pots with straw or bubble wrap perhaps, get a cheap thermometer to keep an eye on things.

 

[pandacular]

Putting them in my garage might be the best solution but I'm still concern that roots will be freezing in my garage when it's -30c (-22f) outside for a long time. The garage is not well isolated, but I guess the trees will be safe from the wind.

Given your extreme temperatures, I would recommend a thermometer with at least a 24hr hi/lo display. Folks on here have also had success with web connected thermometers that allow for configuring alert thresholds.

 

[Gabler]

What you'll want to do is look up both the hardiness zone and the root kill temperature of each species you have. Many trees that can handle extraordinary cold from the base of the trunk upwards can't handle temperature extremes down in their roots. When trees are growing in the ground, their roots are protected by heat stored in the ground. In a pot, their roots will be the same temperature as the surrounding air, which may be fine for the trunk and branches, but too cold for the roots.

For species of trees that can normally live in your zone, you can bury the pots—effectively planting the trees in the ground—to avoid the problem of cold roots. For trees that cannot grow in the ground in your climate, you will want to provide additional protection by moving them into the unheated garage. For tropicals, bring them indoors, of course. In either case, trees need less water in winter, but you should still check frequently, so you can water immediately if the trees dry out.

Here in Zone 7, I generally just set my trees on the ground and water them about once per week, sometimes more frequently, sometimes less, depending on the trees' needs. For trees with sensitive roots, I'll partly bury the pots in mulch to give them extra protection.

The only trees I've ever lost over the winter were trees I had newly collected earlier that same year. They're weaker and therefore need a bit more protection. That's also why we repot in the spring. It gives the roots as much time as possible to recover before winter. Winter is not as scary as many people make it out to be, provided you protect your trees' roots.

 

[pandacular]

Here in Zone 7, I generally just set my trees on the ground and water them about once per week, sometimes more frequently, sometimes less, depending on the trees' needs. For trees with sensitive roots, I'll partly bury the pots in mulch to give them extra protection.

I'm curious how you know if a tree needs water in the winter if it is mulched in or buried.

I plan to mulch my trees in raised planter beds this winter, as well as provide a heat mat for some of the more sensitive ones (hoping to be able to separate an air-layer, which would definitely go on a heat mat).

 

[Gabler]

A couple of other things:

When soil is frozen, trees can't take up water. If exposed to the wind and sun, they can therefore dry out. Keep your trees in the shade, and water them well whenever it's warm enough to wet the soil.

Bonsai soil dries out faster than garden soil, so you shouldn't completely bury your pots. You need to be able to check the soil to ensure it is still moist.

Wait until after the first few frosts to start start protecting your trees. I'm told it's important to expose them to temperatures slightly below freezing a few times to trigger complete dormancy.

 

[rockm]

If by glazed terrace, you mean glass enclosed space, that might be good for the tropical species, but not good for temperate zone trees that require dormancy. Too much heat--and by heat I mean above 37 F (3 C) or so.

All in all, the unheated garage might be your best option for dormancy for you deciduous trees. Pine will be fine outside heavily mulched into a garden bed. You will have to monitor the temperature and watering of the trees while they're in the garage. You don't want temperatures to get above 40 F (4 C), as that can make them break dormancy early. Ideal temperature to shoot for is about 30-35 F (0-1 C). Lower than that isn't really going to be a problem, even if it goes down to high teens F (-8 C or so) every so often.

One thing to remember--Overwintering trees is not about keeping trees "warm." It is about maintaining the lowest temp they can stand for as long as possible into spring. Keep that in mind as you consider where to overwinter them.

And as said, don't bring trees inside early to avoid frosts and shallow freezes (overnight freezes that dip below 0 or a little less).Those temperatures help signal trees to enter dormancy. Also important to be on the lookout for extreme early hard freezes these days. Here in Va. we've had deep cold in the low 20's and even teens F (-6 C and below) in November. That cold was sudden. We have typically only gotten to those lower temps in Dec. Such extremes can catch trees unprepared. These days of uncertain, weird weather require you to pay attention to forecasts closely come Nov.

 

[Deep Sea Diver]

You might want to download and peruse this resource on overwintering theory and methods.

The examples likely will be of some help.

cheers
DSD sends

 

[xray]

Thanks for all the wise answers.
I have Netatmo so I've invested in an additional module that I will have in the garage to monitor the temperature. I've read a lot about over wintering lately I think I have gotten the hang of it. It will be an interesting first winter as a bonsai newbie.

 

[Lorax7]

I’m in zone 5b. For overwintering, I put my Japanese maples, Amur maples, and red maples (Acer rubrum) directly on the ground by the north side of my unheated garage. I pack all my trees close together like Tetris blocks. The most cold hardy species line the perimeter and the least cold hardy species are placed closest to the garage. I fill any spaces between the pots with mulch (I use cypress mulch, but the type isn’t really important) and also put a layer of mulch covering the soil surface in the pots (be sure to remove the mulch from the soil surface in the spring). My backyard is fairly sheltered from wind by bushes and trees, the garage, and the house, so I don’t do anything special for wind protection, but you may want to consider making a windbreak around your trees if your yard is relatively open and windy.

I don’t put my trees on the ground until after we’ve had the first hard freeze of the season. If you put your trees on the ground too early, rodents will make their winter homes right next to the delicious buffet of trees that you’ve set out seemingly just for them. Let them choose their winter accommodations elsewhere first before you put the trees on the ground. Once there’s been a hard freeze, hopefully, it’s too late for them to change their minds and set up shop next to your overwintering area.

After the first significant snowfall, I go shovel some extra snow onto my trees for added insulation. That’s pretty much it. Once winter sets in, I don’t have to worry much about my trees until spring. They get enough water from occasional snowmelt. Shade from being on the north side of the garage keeps them from undergoing too many repeated freeze/thaw cycles and helps prevent them from budding out prematurely in spring.

 

[xray]

Putting the trees on the ground or maybe into the ground might be the best. Unheated unattached garage will get really cold in my zone. I don't know if the concrete ground will be really cold or not.
I'm thinking of getting a cold frame as well, putting it ouside garage on the north side. I watched Mirai talking about winter care and it can differ 10 degrees from air and ground.

Last night temps were down to +1c.
I'm really concern about the winter care.

 

[Gabler]

Putting the trees on the ground or maybe into the ground might be the best. Unheated unattached garage will get really cold in my zone. I don't know if the concrete ground will be really cold or not.
I'm thinking of getting a cold frame as well, putting it ouside garage on the north side. I watched Mirai talking about winter care and it can differ 10 degrees from air and ground.

Last night temps were down to +1c.
I'm really concern about the winter care.

Trees can handle temperatures pretty far below freezing before it's a problem. That said, I suppose you could put a space heater in a detached garage and set a thermostat to turn it off when it warms up to -10°C. Just be sure there's nothing highly flammable near the space heater. If it's in the middle of a concrete floor, away from your trees, that's good.

 

[HorseloverFat]

Much good information shared, already.

Let me just say... I live in NE Wisconsin... On the girthy base of the peninsula on the lakeside... Zone USDA 5a.

And HERE... I am EXACTLY on the fringe for your two deciduous specimens; Acer Palmatum and Ulmus Parvifolia

....if not protected (like coldframe/shed), during my winters ....they do not wake up .

Just to share my experience growing these same species in zone USDA 5a.
(It gets -30dF here as well)