bonsai and cold weather?

Question, and i think more people wonder.

What if it freeses for a long period and the winds are dry.
My trees are outside, but cant give them water can i?

took some in to defrost the outer layer 3cm (only bigger training pots).

grtzz machiel

Hi Machiel,

Its something that on all of our minds in Northern Europe... its the big freeze and don't we know it, -13c in my garden earlier this week.

If the trees are covered with snow leave them alone... a snow covering acts as 'insulation' against the worst of the weather, particularly if there is very cold wind, they are better off on the ground than on the benches. Walters experience with this (Citation please Walter)

The trees will go into suspended animation if frozen solid... DO NOT use warm water on them, this is a killer. Let the trees thaw naturally.

All the 'for sale' yamadori that I am taking to Noelanders Trophee are under 30cm of snow... I hope it thaws before I must pack my vehicle.

Very helpful thus far. I had similar questions.

At what temperatures is it most helpful to keep the snow on for insulation? We recently had below freezing also but what if it only gets into the 20's F

Should I remove snow that has completely buried the trees that I have on the ground?

If my trees are located on the surface of a deep rectangular planter filled with soil is that better then on the ground?

You mention buried under 30cm do you do anything to the pots before the freezing temperatures hit? ( Tilting pots with wedges, etc.?)

Pre thanks.

Joe

Joe,
In general the snow (as Tony mentioned) will insulate the tree. It may actually be warmer under the snow than the ambient temperature. This is why orange growers and nurserymen spray their plants with water during a freeze. Water freezes at 32F, when the plant is frozen in ice at 32f it wont matter if the ambient temps are lower....whats inside the ice will not drop much below 32f.

The wind AND the cold is the real danger. Your trees may be fine with low temperatures on the ground, but if they are not protected from cold harsh winds, they may sustain some damage...another reason to keep the snow.

Your questions
As far as warmth, overwintering outdoors goes, I don't think there is much better than the ground. If your drainage is good you should not need to tilt the pots. Don't remove the snow regardless. Just let it melt. Another danger to removing snow is damage to branches which may be more susceptible to snapping in the cold.

Neil

when the plant is frozen in ice at 32f it wont matter if the ambient temps are lower...

.

That's only true to a point . . . if it is in the 20s for a considerable amount of time (4-5 hours or more) damage is done . . . as Florida orange growers are discovering.

I'll let you know next spring how my trees fared after 2 weeks with temps below freezing the whole time. It was only 32F here last night, and we're gonna have marginal cold nights and temps in the 50s during the day for the next week or so. I worry more about the freeze-thaw repetitions.

So far a couple of my privet look terrible. I'm a bit concerned over some crape myrtle, too.

This year has been bad here near DC too. I am calling it an "experiment" when really it was a snafu. I was away much of November and the snows and cold came before I could get my trees into their customary storage areas. Usually I have well into December for this task. So now most of the pots are buried in snow and ice, although a lot of the trees themselves are exposed. They will stay like that I guess unless we get a good thaw that frees them up. The house protects them from some of the wind, but not a lot. 8F is the coldest temp I have seen so far. I get pretty depressed if I have a lot of loss in the spring. I'm not sure I'm looking forward to spring!

Thanks for the info.

My concern is due to having 3 pots last year break and trees broke down to almost nothing. I have since been taking a active roll in winter protections.

There seems to be some misunderstanding about the effect of snow and ice cover on the temperature of something. Whatever is under the snow or ice WILL eventually get to the same temperature as the surrounding air in accordance with the second law of thermodynamics. Just because water freezes at 32 F doesn't mean it won't get colder than that once frozen. However, ice and particularly snow will insulate an object which means that it will slow the rate of heat exchange with the air. So if the pot in the snow is at 30 F during the day, and the temperature dips to 8 F at night for several hours, the snow may keep the pot warmer than the 8 F until morning when the air will presumably warm up again. The pot's temperature will still drop during the night - just not as fast as it would without the snow.

Also note that water will stay at 32 F while in the process of freezing. This is the advantage gained by spraying water on oranges during a freeze. Again however, once it is frozen, the ice will drop to the ambient temperature.

Don't get me started on wind chill...

However... A tree, left outside and uncovered will be effected more rapidly and more severely by wind, dropping humidity and cold much more quickly than a tree covered with snow or an artificial covering.

A great webpage to look at temperate trees covered with snow taht have been watched for years is on Wolfgang Putz bonsai gallery.

Jay

TY Velo for the added clarification. Is there an equation calculating the wind chill freezing temperatures, residual head of the soil decomposition, and snow accumulation?

I'm just kidding.

It ain't the wind "chill" that kills tees. It's the wind dryness. Wind chill only affects warm blooded animals. (Cold blooded animals have already had the good sense to have hidden themselves away).

Lots of interesting facts......but the MOST RELEVANT FACT is not how cold ice will get at any elevation in any amount of wind.....the most RELEVANT FACT it is that trees die because people fail to anticipate and take proper precautions by asking "what if". In the case of bonsai, people let trees die, weather doesn't kill them.

My pre-bonsai & stock trees are outdoors in 8 inches of mulch, under snow I shoveled on them, and under benches covered by tarps. The best trees are in a cold garage with excellent protection.

The real issue for hardy trees is not the freeze. It is the freeze and thaw, freeze and thaw, which is why covering them with snow is recommeded. The snow keeps a more constant temp. We also bury hardy trees in Michigan, pot and all. This protects the roots. The real villan is the wind and the drying effect it causes. Much also depends on the hardiness of the tree.

"Man made" ice to insulate trees in sub 32 degree weather.

Q

these are answers, thnx.

My trees are outside and where tha past years outside, never lost one
i was just wondering how and what.

precoution in sence of keeping trees indoors anyone at low temprarures....how those that work?
have to trees indoors for the first time at 6 c
kan i work on these?