Variance in hardiness by locale

[needmore]

I started a thread on the English section of the French forum - http://lesbambous.fr/forum/viewtopic.php?f=78&t=7473

I'm quite surprised as the responses, particularly the one from Switzerland and would appreciate any insights. I am really curious about the latitude thought I had, w/o high-speed internet I'm not going fishing for data but I am curious what the difference in the angle of the sun from my area to some of the respondents so if anyone here feels like looking into it...how much of a factor is stronger sun on frozen ground and how can one measure the difference between sun 'strength'? FoxD I expect a full report...

For the most part the one from Switzerland seems to have very identical conditions to a killing freeze here so what can be the variables? One obviously is that the damage has not shown up yet and will when they warm back up some. Otherwise it seems like soil composition, wind exposure, health of plants going into winter, snow cover are factors to consider. Wind exposure seems to not be materially different, snow cover may be a small factor but I get damage in those conditions with snow cover.

Thoughts?

[canadianplant]

Just for the record, you are asking what exactly dictates hardiness? Or how "hardiness" may be defined in different countries, citys etc...?

[needmore]

I'm asking why in one locale bamboo would be killed to the ground and in another be mostly unfazed in similar conditions. What variables would explain this?

[Squishee]

Needmore, I think it really just comes down to microclimates plus the amount of years a particular bamboo species has been given the time to "develop". After that, every year that species should become more used to whatever new climate it is exposed to.

[needmore]

In this case I don't get the impression that age or microclimate are factors.

[Tarzanus]

According to what I've read, sun exposure during the winter can be a problem for bamboo when temperatures are below freezing, which means that the plant looses water that can not be replaced. The second killer during the winter is dry cold air, that literally sucks the moisture out of the foliage (during the latest cold front in Europe, my Phyllostachys aurea got quite some damage because of the wind, I'll see how much damage there is in a week or two when I can finally uncover it).

There are soils that dry out or freeze faster / deeper in the winter. That is most likely the key factor in most of very frost resistant bamboos.

[canadianplant]

Dont forget length of cold/groundfreeze and the like. Sure for instance, trachycarpus can take -20C, but not for a really long period of time right? Also, the length of growing season. You may have the same temps, but not as long, colder winter etc. Also windchill for some people.

If your talking about 2 plants in the same spot, one dies, one thrives... That would come down to induvidual specimin, how odl they are before beuing divided, how well they were devided and shipped, water stress during shipment... This is when microclimates may play a role, because a plant may also survive in one area of your yard, and not another...

[moriphen]

Europe is gifted with many large bodies of water and relatively few mountain ranges to block said Atlantic/Baltic/Mediterranean air masses. In addition North America is 7 million square miles larger then Europe making our air mass continental instead of Pacific or rarely Atlantic. Switzerland is where the ocean modified air stops much like the Rocky Mountains in North America where the Pacific air mass stops. Of note this winter we are having a rare Pacific air mass over the entire lower 48 states, as you may have noticed this is much preferred bamboo growing weather.

[needmore]

Yes, I am aware of all of these things mentioned...but... the point I'm trying to make is that they had frozen ground for many days in a row with daytime highs not reaching freezing, night time lows in the single digits to subzero F and little to no damage to marginally hardy species. I don't see how micro climate can trump multiple consecutive days of sub-freezing temps for highs, single digit to subzero lows - a few hours yes, days, me don't think so. Micro-climates have a short protection window that these conditions exceeded dramatically. Am I missing something?

[canadianplant]

So your wondering why, "marginally hardy species" (as you put it), seemed to have survived semi long term cold in europe, and why they see, to fry in other areas? Sorry, I dont think I understand the way your explaining it. COuld you paste some of the other thread on this one maybe?

[Alan_L]

Yes, that's what he's asking. If his bamboo here gets subjected to several days of single digits (F) with temps never going above freezing, he gets fried bamboo. When the same thing happens in Europe, bamboo is fine.

There must be a missing factor Brad -- is it wind? Are you thinking it could be that they get less sun in winter than you do, and that may be the factor?

[Squishee]

I agree about the dry cold being a bamboo killer. All my bamboos are perfectly fine when it's freezing or even snowing outside. However, when the snow melts away and it gets windy.....I really start to notice leaf curl and such.

[jd.]

For the most part the one from Switzerland seems to have very identical conditions to a killing freeze here so what can be the variables?

The oceanic climate over much of Europe tends to limit the days of dry winds and extreme cold, unlike the continental climate here.

The less direct sun in Switzerland and especially in northern Europe where the winter sun is lower in the sky than here in the Midwest is another potentially interesting factor to consider. Not only do we have more cold and more dry winds here, but we also have a more powerful winter sun to assist in the bamboo freeze-dry process.

Based on the performance of the bamboo here in a mild winter versus prior winters, I speculate that there is a cumulative effect in that bamboo can only tolerate a limited number of days of temperatures sustained below freezing over the course of winter.

These past months here, winter temperatures on average have remained above freezing, unlike any winter before since bamboo has been growing here. Historically I have seen few if any unprotected green leaves survive a winter here, while this year I observe a couple plants with much green still remaining!