Winter Thermodynamics....

Discussion in 'HortForum' started by Aussiebob, Nov 29, 2006.

  1. Aussiebob

    Aussiebob Active Member

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    OK.....here's one for someone with lotsa university learnins about hot and cold stuff...

    I have a fairly large yard with lots and lots and lots of pots and seedlings etc....at the start of winter I put them all together in a nice groups. I have 1 big group under a Coast Redwood, another big group in one of my vegetable planter beds......I figured that in a group...they could cuddle up and spoon each other to keep warm....and at least they talk to each other incase we got one of our not too uncommon 2month rain long shower - and I didn't feel like going outside and saying g'day etc....

    I also have a wooden deck - which is about 2' off the ground - which is open on 3 sides so air etc circulated underneath it etc. I built a couple of wooden tables/benches about 3' high (also open to air underneath) with a frame over the top which I stapled poly over....the intent being to let some baby seedlings sit in there in winter and not get washed away by one of the aformentioned not too uncommon 2month rain long showers.

    Well anyway......for all those who don't know.....the local temperate Vancouver population is suffering through what seems like a 1 in a thousand year deep freeze at the momment (I blame global warming and the Japanese mafia who bought one of those weather control machines from the Soviet Union when they had a fire sale about 16 years ago - but hey that's just me) anyway we've been in snow for about a week now and the last few days have been down to about -10 (metric)....

    The group of pots under the Coast Redwood are snow free, the group of pots in the platerbed are burried in about 2' of snow - which has now turned to ice, the seedlings on the table, which has a poly "tent" are protected - but have about 2' of snow/ice on the poly.

    Any bets on the outcome as to which group (if any) will survive?????

    Cheers
     
  2. jimmyq

    jimmyq Well-Known Member 10 Years

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    non answerable because we dont know what kind of plants they are, but, I would say the ones buried in snow are best protected. the ones with air movement around them on 3 sides, least protected due to cold and desication. the poly covered ones should fair reasonably well. spoken not from a university education standpoint but rather from near 20 years of retail and wholesale nursery experience.

    in regards to the 1 in a thousand winter, my personal recollection of the worst winter was either 1989 or 1990 (VERY cold and dry with lots of wind) and perhaps 1994, lots of snow, fairly cold.
     
  3. bcgift52

    bcgift52 Active Member

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    Well it depends on what you have growing in those pots - as for bets, if we're talking money I'll put my dollar on the 'snow covered' lot - and if Daniel gets cross with us, I'll put a Metasequoia on the same 'snow covered' lot.
     
  4. Aussiebob

    Aussiebob Active Member

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    Most of the plants under the Coast redwood are 4" potted Dawn, Coast or Giant Redwoods....plus athe odd spruce, fir - in all about 50 or so.

    The plants on the table etc are a few coast redwood & pacific yew cuttings that I'm trying to propogate, plus some Azelias and similar plants....nothing more than a 6" pot - about 20 of them.

    The plants in the vegetable garden bed - aside from the inground winter lettuce/beats/spinach etc are Azelias and similar plants in 6" pots....about 30 of them.

    Cheers
     
  5. growest

    growest Active Member 10 Years

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    Bob and all--also not a university thermodynamics grad, but have lots of container plants overwintering every year...

    Any soil not covered by snow in the cold snap was well frozen, we got to like -10/-11C for a couple nights, and that freezes any containers pretty solid, as well as exposed ground...which was not at all frozen before the snow started to fall. On the other hand, I dug down thru our snow pack, and found the veggie garden soil nice and unfrozen, so the snow covered plants are surely going to be happiest.

    The raised deck area is quite an interesting problem...I know you worry as I do about containers sitting in water, drowning roots, so the deck gets them up safely away from that. But the source of heat in winter is the ground, which those pots are separated from. I would expect them to be difficult to keep unfrozen in any cold snaps...have to keep air underneath warmer than ambient.

    I also notice some foliage was damaged by the cold, ceanothus here is looking very black, for e.g. Anything under the snow is squashed, tho springing back up now, and pretty well untouched by the cold. I know some plants are broken by lots of snow, but most of mine are younger, and still pretty elastic...and did far better getting buried than being upright and freeze-dried.

    Interesting subject, and the answers can be financially significant!
     
  6. smivies

    smivies Active Member

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    Roots are much more sensitive to cold then stems. Some trees & shurbs we would normally considered hardy will experience root death below -2ºC (ie. giant sequoia).

    So, given the three locales you describe, the spot with highest survival rate for a single species would be the planter bed with the snow (insulated above with snow & benefiting from the ground's thermal mass).

    The locales under the tree & under the poly tent are harder to rank. The lack of snow under the tree means the top & sides of the pots would loose heat but the bottom would benefit from ground heat. On your deck, the bottom of the pot is 'exposed', but the rest of the pot is somewhat sheltered.

    If the pots froze solid during your -10ºC nights, you've likely lost the trees in them (expect for the Metasequoia). Good Luck

    Simon
     
  7. Rima

    Rima Active Member

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    If the seedlings aren't mulched in well, I wouldn't expect a terrific outcome unfortunately. Poly doesn't do enough. Can you not however, brush off the worst of the snow to be sure it won't collapse inward?
     
  8. Aussiebob

    Aussiebob Active Member

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    I vetured out into the great brown muuuuddy slush of my backyard last night......everything has thawed........but what a mess....

    Everythink still seems green.....but I suppose I'll only know in spring if everything is still alive etc.....

    The stuff on the table with the poly tent etc seems freeze dried, so I watered it all, the stuff under the redwood tree umbrella seems in the best condition - as minimal snow made it through to cover the foliage/pots etc etc etc....

    The stuff in the planter bed is ......well its a muddy mess....but like I mentioned above....I suppose I'll only know in spring if it's dead or alive.....who knows thay may be happy as a pigs in mud.....

    I do know this though.....My vegetable garden is trashed......lettuce and spinach that I was happy harvestinmg up untill about 3 weeks ago....is a a squashed brown mess.....the leaves have become one with the mud......I have no idea how the beetroots are going....but the above ground leaves are not good....

    I suppose the ones on the table are the ones that I'm most curious about......maybe next year I'll put a layer or 2 of rigid insulation under the pots etc....maybe that will protect them from the japanese mafia induced snap freezes.....


    Cheers
     
  9. K Baron

    K Baron Well-Known Member

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    Hi Aussiebob...I covered my artichoke with a large plastic pail and it survived the -11 celsius weather...hmmm protection from trees and snow cover...we are on to something...my 7 m. Eucalyptus gunnii seems more worse for wear....Japanese weather machines????? Hmmmm?
     

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