Extreme weather and Rock Juniper.

David M. Martin

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I need some advice on weathering a Japanese Rock Juniper over the winter. I live in Indiana where the weather can be extreme in any season, to include below zero temps and the occasional ice storm.
The question is simple really: Are there any precautions I can, or should take to cover the tree in extreme weather conditions, and if so, what would I need to use?
 

JudyB

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David, I do not know if your Japanese Rock Juni is any different in the hardy department than normal junipers, but I live in much the same type of winter conditions that you probably see. I have junipers that have survived on benches with no protection during sub-zero winters with windy conditions. They can really take a lot of abuse. The only thing I would caution (and again, maybe yours is less hardy) is about ice buildup. I did loose a largeish branch to ice buildup and then significant wind one winter. I'm sure someone more knowledgeable than I will chime in to help with your specific plant...
 

David M. Martin

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Thanks Judy, It's a very hardy tree, but I've worked hard on it and don't want to take any chances. Again, thanks for your input and if nothing else is posted, I'll move it to my garage if the forecast calls for freezing rain or sleet. Good luck with your Bonsai endeavors!
 

Brian Van Fleet

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Assuming this is a Procumbens Nana, it's hardy to zone 4. If it's in a bonsai pot or small nursery container, the roots will be MUCH more susceptible to cold; freeze-drying really. It needs to be exposed to shorter days, colder weather, and a few frosts at a minimum, before moving it in to an unheated garage, or mulched in against the North side of your house.

When I lived in Iowa, I had a much smaller collection, and built a coldframe that fit against the back of the house, and everything was mulched inside it. I built it around a basement window, so I could check on them from inside even when the entire coldframe was buried in a snowdrift. They were frozen, but stayed frozen and didn't need much attention.

Irregardless of it's hardiness, do not simply leave it outside on the bench. Even in my temperate climate, with nothing but fully hardy trees, I don't leave them out on the benches in the winter. Moderating temperatures by covering the pots with pine straw and settling them out of the sun and wind makes winters much easier for the trees and me.
 

David M. Martin

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So Brian,,,,,, does that mean it shouldn't get any Sun during the winter? Am I over thinking your answer by asking that question? It seems like you're saying that I should allow it to "Toughen Up" some,,, but should plan on insulating the roots. and remove it from rain, snow, sun etc. I'm also curious to know more about your freeze-drying comment. Does that statement mean that since the pot is so small and not a lot of soil depth to guard the roots, that they could possibly be "Freezer Burned"? I'm asking this also because you made the comment about your Bonsais being frozen and not needing much attention. I don't mean to be a nuisance with all these questions but I've grown fond of this Juniper and have turned it into something that really looks like a Bonsai instead of the "Strip of Evergreen" that was presented to me on a past birthday. I kept it inside last winter and then found out that I shouldn't have done that. That's when I joined this forum and started asking before I made anymore mistakes.
 

Dav4

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You want to keep it out of direct sun and wind when its soil is frozen...if the foliage cant transpire due to frozen soil and its out in the full sun and wind where water demands are much higher, the foliage will quickly become wind burned and dried out. Mulched in a protected area out of the wind and direct sun is where the tree needs to be. In MA, I kept trees mulched up against my garage foundation, mulched into my veggie garden with a burlap windbreak, and mulched on the floor of my unnattached garage.
 

Brian Van Fleet

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Let's take these one at a time...

So Brian,,,,,, does that mean it shouldn't get any Sun during the winter?
Sun isn't as important in the winter, a little light is fine for dormant evergreens, and is unnecessary for leafless deciduous trees. Some sun won't hurt as long as the roots aren't frozen solid...more on this in a second...

Am I over thinking your answer by asking that question?
Nope.

It seems like you're saying that I should allow it to "Toughen Up" some,,, but should plan on insulating the roots. and remove it from rain, snow, sun etc.
Yes, let it toughen up. They need to be exposed to the elements and seasonal changes to be strong, our job is to pay attention and make sure they have the resources to thrive.

I'm also curious to know more about your freeze-drying comment. Does that statement mean that since the pot is so small and not a lot of soil depth to guard the roots, that they could possibly be "Freezer Burned"?
You're mostly right. Trees in the ground typically have root systems that extend deeper than the frost line, and bonsai don't have that safeguard. Water in the form of ice in bonsai pots is not available for roots to absorb. If you look closely at a frozen coarse soil, the granules actually look dry, and you can see ice crystals between them. I don't remember the chemistry (sadly) but it looks like the moisture leaches out of the soil as it freezes.

More importantly, roots can't absorb frozen water, but evergreen trees will transpire in the sunshine, and need to take up water from the roots to replace it, but frozen roots can't meet that need. This is freeze-drying. I actually did this to a white pine last winter. Cold weather hit unexpectedly, I set it on the ground, not under a bench, and raked up a bunch of leaves to cover the pot. The next day was warmer and very sunny. The tree got full sun for a few days, but the roots stayed frozen under the leaves. Bad move, and the tree reminded me of it all year with yellow-tipped needles that are just now (finally) dropping off.


I'm asking this also because you made the comment about your Bonsais being frozen and not needing much attention.
When they're frozen, out of the wind and out of the sun, they just don't need a lot of attention in the winter. Down here, mulched in and under the benches, we get enough rain that they don't dry out under the mulch.

I don't mean to be a nuisance with all these questions but I've grown fond of this Juniper and have turned it into something that really looks like a Bonsai instead of the "Strip of Evergreen" that was presented to me on a past birthday. I kept it inside last winter and then found out that I shouldn't have done that. That's when I joined this forum and started asking before I made anymore mistakes.
We've all done it...killing trees is just part of it for a while, but always learn why.
 

crhabq

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Brian,

Thanks for your advice. Here in my locale, late winter (damn those winds) and early spring (damn those spring frost, aka false springs) These are the real killing times for my trees I've found. FinallY, I think I've figured it out and won't kill so many trees. Now to just get off my lazy a** and go but some straw bales.

Ray
 

David M. Martin

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Wow! Thanks for going out of your way for me Brian! Now that you've explained it that way it just makes sense. If I were a deeper thinker I might have figured it out but the chances of that were probably slim. Glad I'm on this forum, especially now. My Juniper has survived in spite of my mistakes in the past two years so it's probably going to be a lot happier because of the helpful people on this forum. It just might become a very old tree!!!!
 

Brian Van Fleet

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No problem guys, best of luck. Those late-spring freezes can be deadly...it is always tempting to get them out early, but it's best to be safe.
 

fore

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Brian, are you saying that evergreens shouldn't be under the protection of a greenhouse? I bought a hooped designed, 6 mil. plastic covered greenhouse for my deciduous trees and just planned on keeping my shimpaku's, jbp, and hinoki cypress in there as well. My ponderosa pine I planned on leaving out. (I have no garage, n. side of house open to the public ((and possible theft)), and my basement doesn't get cold enough. Hence the greenhouse)
 

edprocoat

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Back when I used to stay in Ohio for the winter I would take my trees and dig a hole and bury the pot about two inches under the soil line I would then add mulch mounding it up the trunk. I bought a large clear plastic box, like tupperware with the lid from wal mart, I would turn the box over and place it over the tree and then use tent stakes to secure it to the ground. The box would fill with humidity in the daylight appearing as wetness on the roof and sides of the clear box which would seem to filter the light a bit. I would leave them like this until spring was sprung and they did well. I had over two feet of snow on the box one morning so I brushed it off, you know that snow is an excellent insulation beleive it or not, so I left it around the box. when the weather had cleared I dig up the pot and washed it off, the first thing I noticed was that my moss grew fantastic. These were pines and junipers, I doubt it would work with any tropical variety though.

ed
 

Brian Van Fleet

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Brian, are you saying that evergreens shouldn't be under the protection of a greenhouse? I bought a hooped designed, 6 mil. plastic covered greenhouse for my deciduous trees and just planned on keeping my shimpaku's, jbp, and hinoki cypress in there as well. My ponderosa pine I planned on leaving out. (I have no garage, n. side of house open to the public ((and possible theft)), and my basement doesn't get cold enough. Hence the greenhouse)

No, I said it needs to be exposed to shorter days, colder weather, and a few frosts at a minimum, before moving it in to an unheated garage, or mulched in against the North side of your house...and that moderating temperatures by covering the pots with pine straw and settling them out of the sun and wind makes winters much easier.

IF you can accomplish that inside a greenhouse, great. But, depending on the size and location of the greenhouse, your challenge will be preventing solar gain. Even in cold climates, small greenhouses can easily heat up 60-80 degrees above outside temperatures, then drop right back down to outside temperatures at night...those swings are worse than freezing solid and staying under snow all winter.

You may consider buying a min/max thermometer so you can monitor the temp swings and understand the climate inside the greenhouse very quickly. Enough warm days will lead to bud-break and root activity, and once the roots start to become active, their tolerance to cold is about gone. You don't want that happening in Ohio in February.

Additionally, not all evergreens have the same hardiness...black pines are more sensitive to cold than ponderosa pines, for example. You could probably get away with leaving the pondy out all winter, but definitely set on the ground in a protected spot.
 

sean f

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i have a greenhouse and i will move my trees in there in extreme cold,but like brian said the temp swings between night and day are extreme and i have lost trees because of it
 

JudyB

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If you are going to be successful (in ohio) with a greenhouse, you must invest in an exhaust fan and some automated louvers to suck the cold air in and push the warmer air out during sunny days where that heat buildup happens. The fan and louvers are activated by a thermostatic control that you set to a temp when you want them to come on. Look in greenhouse supply stores for these.
 

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