l'acclimation hivernale
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Smets Philippe
- Maître Bambou
- Messages : 5209
- Enregistré le : 16 janv. 2008, 13:19
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Re: l'acclimation hivernale
j'aime bien ce post dans le forum de bambooweb
post rédigé par chris , merci a lui
[i]Guys - great contributions, many thanks, here is some history, some of which I might have posted before:
Way back in 1999, George Shor defined the min temp thus:
"Many species will tolerate the minimum temperature for short periods of time and experience only leaf damage"
This implied that the min temp was for complete defoliation, or worse, and was considered a bit dangerous in our increasingly litigious world - what if someone spent thousands of dollars on a truckload of specimen subtropical bamboos, and they all died at the min temp we specified in the List? A minimum temp has to be interpreted as a minimum for survival, not a maximum for not dying, if you follow me. ABS might get taken to the cleaners.
Therefore the wording was changed, basically with the aim to move up from potentially plant-killing temps to the start of significant leaf damage. A fine intention, and upgrading the temps accordingly saw many changes, but never got implemented for all bamboos, partly because of lack of information. We changed all the mins for Bambusa species to something more reasonable, see http://www.bamboo-identification.co.uk/ ... iness.html as their hardiness was seriously overestimated. However, there are some tendencies that made it hard to stick to this principle. Firstly many growers take pride in getting their plants down to low temperatures and want to say something like, "I grow this species right down to -xx no problem". Secondly there are different ways of recording the temp, air temp vs ground temp for one thing - hands up those whose thermometers are in a Stevenson screen in the correct position for a meteorological weather station. You may have heard, "The weatherman said it was only 0 but it was -10 at my place". Also dare I say that nurserymen don't want to scare off customers... If there is now more consensus and self-discipline, then let's get those min temps up, up, and up.
The problem with Zones - well just look at the last 2 winters!! I've even lost some plants indoors!
Wind chill is a very useful concept here -good point - I would say we should be talking windchill temps and my wording used to include "on a calm night" & "winds exacerbate the cold effect" - current editors of that section could usefully clarify whether it is still the case that the min temps are for still conditions only?
Chris
[/i]
post rédigé par chris , merci a lui
[i]Guys - great contributions, many thanks, here is some history, some of which I might have posted before:
Way back in 1999, George Shor defined the min temp thus:
"Many species will tolerate the minimum temperature for short periods of time and experience only leaf damage"
This implied that the min temp was for complete defoliation, or worse, and was considered a bit dangerous in our increasingly litigious world - what if someone spent thousands of dollars on a truckload of specimen subtropical bamboos, and they all died at the min temp we specified in the List? A minimum temp has to be interpreted as a minimum for survival, not a maximum for not dying, if you follow me. ABS might get taken to the cleaners.
Therefore the wording was changed, basically with the aim to move up from potentially plant-killing temps to the start of significant leaf damage. A fine intention, and upgrading the temps accordingly saw many changes, but never got implemented for all bamboos, partly because of lack of information. We changed all the mins for Bambusa species to something more reasonable, see http://www.bamboo-identification.co.uk/ ... iness.html as their hardiness was seriously overestimated. However, there are some tendencies that made it hard to stick to this principle. Firstly many growers take pride in getting their plants down to low temperatures and want to say something like, "I grow this species right down to -xx no problem". Secondly there are different ways of recording the temp, air temp vs ground temp for one thing - hands up those whose thermometers are in a Stevenson screen in the correct position for a meteorological weather station. You may have heard, "The weatherman said it was only 0 but it was -10 at my place". Also dare I say that nurserymen don't want to scare off customers... If there is now more consensus and self-discipline, then let's get those min temps up, up, and up.
The problem with Zones - well just look at the last 2 winters!! I've even lost some plants indoors!
Wind chill is a very useful concept here -good point - I would say we should be talking windchill temps and my wording used to include "on a calm night" & "winds exacerbate the cold effect" - current editors of that section could usefully clarify whether it is still the case that the min temps are for still conditions only?
Chris
[/i]