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Bill, do you have any sense that there is an opportunity to modify the temperature ratings in the SSL this year? You may have gone to press already but just wondering if that conversation has happened yet and if so what is the dialogue like regarding these changes?

Bill, any updates?

I am still working to get the sources signed up so I have not even touched on the species list. I plan on getting all of the suggestions put together and send it to Chris tomorrow.

Bill

Is there an opportunity for input on temperature ratings?

Sorry for the delay.
Yes if you have any suggestions and observations post them here and if they do not make this years species list I can still get the changes approved for the online version.

Bill

Here would be my suggested changes based on what I've seen over the past few years, I probably included some misspellinks to dodge!

This is based on the assumption that the SSL ratings indicate the temperature at which leaf burn may initiate based on observations of plantings >= 5 years in-ground. Culm damage estimates would be different and perhaps more instructive as leaf burn is not an indicator of top hardiness really, at least in many cases. A switch to severe top damage ratings may be a topic worthy of discussion although for the tropical species I think that leaf burn temps can be much more 'useable'. To list ANY bamboo leaf burn free to beyond say -5F would vastly exceed my observations.

Arundinaria gigantea – A special case, it often shows leaf burn at first frost but holds green leaves to subzero F
Bashania fargesii - +5F ----- +8
Brachy. densiflorum – 0F
Fargesia denudata - +3F
Fargesia dracocephala ‘Rufa’ – 0F ----- +3
Fargesia nitida - +5F
Hibanobambusa – both forms - +3F ----- +5
Indocalamus latifolius – 0F
Indocalamus longiatritus – 0F
Indocalamus tesselatus – 0F
Phy Angusta - -2F
Phy Arcana - 0F
Phy atrovaginata - 0F
Phy aurea & forms - +8F
Phy Aureosulcata - -2F
Phy aureosulcata ‘Alata’ - -2F
Phy Aureosulcata ‘Aureocaulis’ - +3F
Phy Aureosulcata ‘Harbin Inversa’ – 0F
Phy Aureosulcata ‘Harbin’ - +3F
Phy aureosulcata ‘Spectabilis’ - -2F
Phy bambusoides - all forms ------+8°F to +10°F
Phy Bissetii - -2F
Phy Dulcis - +3F ----- +1
Phy Dwarf Bissetii - -2F
Phy Edulis ‘Moso’ - +8F ----- +4
Phy elegans - +5F
Phy Glauca ‘Notso’ - -2F
Phy Glauca ‘Yunzhu’ – 0F
Phy Heteroclada ‘Purpurata’ - +8F
Phy Heteroclada ‘Solidstem’ - -2F ----- +2
Phy Heteroclada ‘Straightstem’ – 0F
Phy humilis - +3F
Phy iridescens - +3F ----- +5
Phy Lithophylla - +8F ----- +10
Phy Makinoi - +0F
Phy Mannii ‘Decora’ - 0F
Phy Nidularia - +8F
Phy nigra - +8F
Phy nigra ‘Hale’ - +5F
Phy Nigra ‘Henon’ - +3F
Phy nigra ‘Megurochiku’ - +3F
Phy Nigra ‘Shimadake’ - +5F
Phy Nuda – 0F
Phy Nuda localis – 0F
Phy Parvifolia - +3F ----- +5
Phy Praecox - +5F
Phy Propinqua ‘Beijing’ – -2F
Phy Rubromarginata – -2F
Phy Spectabilis - -2F
Phy Stimulosa - -5F
Phy Violescens - +8F ----- +6
Phy Viridiglaucescens - +8F
Phy viridis - +5F
Phy viridis ‘Robert Young’ - +5F
Phy vivax – all forms - +8F ----- +5
Pl. juxianensis - +3F
Pl. oleosus - +3F
Pl. simonii - +10F
Ps viridula - +7F
Ps. japonica - +7F ----- +8
Sarocalamus fangiana - +10F
Sasa megalophylla - +8F
Sasa nagimontana - +3F
Sasa nipponica - +8F
Sasa oshidensis - -2F
Sasa palmata - +8F
Sasa senanensis - -2F
Sasa tsuboiana - +5F
Sasa veitchii - +8F
Sasaella bitchuensis - +5F
Sasaella hidaensis muraii –0F
Sasaella masamuneana ‘Albostriata’ - +5F
Sasaella masamuneana ‘Aureostriata’ +10F
Sasaella masamuneana green form – +3F
Sasaella ramosa – 0F
Sasamorpha borealis – +3F
Semiarundinaria fastuosa - +8F ----- +6
Semiarundinaria fastuosa ‘Viridis’ - +3F ----- +6
Semiarundinaria makinoi - +5F
Semiarundinaria okuboi - +5F
Semiarundinaria yashadake ‘Kimmei’ - +8F
Shibataea chinensis - -2F
Shibataea kumusaca - -2F
Shibataea lancifolia - +8F ----- +5 -----Brad- here are my observations over several years for Middle Tennessee. We have not been below 0°F in the last 5-6 years. - David

Would it make sense to look at those as "wind chill" temps? As we unfortunately know, temperature is only part of the equation.

I wonder why most bamboo resources use temperature ratings anyway, is that not uncommon for most plants? Don't we usually go with zonal ratings? I'm not sure that knowing the temperature at which leaf burn initiates tells us much about the hardiness. For example, A gigantea seems to be one of the first to show leaf burn and very early in the season but it will hold leaves as well as anything through most winters here.

I'm just concerned that the SSL says that 'The minimum temperature is the point at which leaf damage begins to appear after a short exposure to the temperature.' If that is the standard then I interpret Phyllostachys nuda for example to not show any leaf burn at say -15F, as it is rated to -20F. But Phy nuda shows leaf burn very reliably at 0F every year here. There are a handful of species I see that can go a tad subzero F before showing leaf burn. This year we have dipped down to a fraction below 0F and I see some burned leaves on everything except Phy stimulosa where I can't find a single burned leaf, a few species the burned leaves are few and could be unrelated to cold but they are burned. We have not been very windy this year either.

I'm not trying to harass the SSL team, they do a great job with few resources I just think that converting to a system using a conservative 'top hardy to zone blah' would be simpler and more instructive.

O.K. that concludes my annual rant...

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

Chris S wrote: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

In the past I've suggested that Wind Chill might be a better measurement than temperature, but nobody else seemed to like the idea.

foxd wrote:In the past I've suggested that Wind Chill might be a better measurement than temperature, but nobody else seemed to like the idea.

It was an idea before its time.

Alan_L wrote:

foxd wrote:In the past I've suggested that Wind Chill might be a better measurement than temperature, but nobody else seemed to like the idea.

It was an idea before its time.

I guess that is better than an idea whose time should not have come.

Chris, I agree that using zones is not really an improvement if the intent is to say hardy to zone X, one would need to be very conservative on that. Using air temperature, I have had 2 consecutive zone 7a winters but there is considerable leaf damage and some top damage to species not at all considered vulnerable in zone 7a. Using wind chill, I'm back in zone 6a...

Using zones to define the expected performance of a given species at maturity would be my recommendation. For example lets say atrovaginata in zone 6 is expected to reach 32ft by 2.5 inches at maturity with slight to moderate leaf burn, and atrovaginata in zone 7 is expected to reach 38ft by 2.75 inches at maturity with little or no leaf burn.

I've also observed a Yellow groove grove that was pushing 20ft, and sprawled out in my area which had very little leaf burn while my YG which has only seen 2 winters looks almost completely leaf burned which I would account directly towards the maturity of the grove. Only the largest culms on my YG are the ones that still held some leaves. I'm expecting that once all my bamboos mature, they will be much hardier even with severe winters like this one.

In the northeast where residual snowfall is almost a guarantee with lake effect snow, the amount of foliage produced by the bamboo matters more than anything else since they are the ones that get bent down by the snow and insulated all winter. This advantage might only be for juvenile bamboos since they bend over so easily and have a large proportion of foliage to culm diameter.

Based on leaf burn observations I've seen so far, most of the species will start leaf burning once it gets below 0F, so the -10F, or -20F temperature ratings are perhaps used for the temperature they top kill, or just overstatements of their hardiness.

Hello All,

Perhaps presenting the "Min. Temp" as an observed average would be more descriptive of actual bamboo performance.

Perhaps "Minimum Temperature" = "The average observed minimum temperature is the temperature at which bamboo leaf damage begins to occur. Many factors including wind, humidity, topography, maturity and drought may effect the minimum temperature value by several standard deviations for any unique planting location. Bamboo hardiness may be partially described by the temperature at which leaf damage, top kill, and rhizome system death occur. Top kill, and rhizome death typically occur at lower temperatures than leaf damage, but they also will be effected by variables unique to their planting site."


Average, by its definition, indicates variation (in temperature in this case) and would allow some wiggle room for the lawyers, and would give the prospective bamboo owner expectation of variations from the stated minimum temperature. The intended use of the bamboo would then drive the decision process.

David