protected cold frames

Kathleen Sayce
Tue, 20 Jan 2009 18:13:14 PST
Thanks for those details. Let me tell you a bit more about the  
conditions we see here in winter.

I garden in USDA zone 8, sometimes zone 9, depending on the strength  
of El Nino-Southern Oscillations and where the Pacific Decadal  
Oscillation is its cycle, which now definitely is in the cooler  
wetter part of its cycle. During warm dry cycles & ENSOs, frost free  
winters are common. During cold wet, the present winter is typical,  
solid zone 8 to upper zone 7 weather. 85-100 inches of rain is  
typical, most of it falling in fall-spring, with cool dry summers.  
This is just above the Columbia River on the coast, in the Pacific  
Northwest. In the recent cold spell this winter & late fall, we saw  
temps to 18F here (actually 22 at my place, but I'm in a warmer spot  
than the official weather recording station), and our winds are  
routinely above 80 for several storms each winter. Last winter we had  
3 storms in 3 days, with winds during the last two 120 mph plus. The  
anemometers all died in this area, so we don't know what the max  
winds were––the devices reached around 127 mph and blew away.

My problem, or should I say dither factors, in deciding what to  
build, have more to do with excessive wet and very strong winds than  
with winter cold. So I envision my proposed cold frame primarily as a  
rain shelter, but one that needs sturdy construction so the glazing  
can be tied down/anchored/bolted in place in strong winds. I saved  
some polycarbonate twinwall glazing from a recent sunroom rebuild  
(not mine, unfortunately, but our rental place), so plan to use this,  
as it can take direct strikes from wind-blown branches and clams  
dropped by crows (did I mention the tidelands a few feet away?),  
which all hard surfaces, including cars, roofs, decks and roads, are  
subject to. I also know I'll be trying copper strips for slug and  
snail resistance.

The dither factors that remain include: inside height when closed.  
Anchoring the panels, when open or closed, in the wind. How deep to  
set the gravel base for good drainage.

So, your information helps me, though as you can see, I am still  
pondering, and would love to hear from others about their systems.
I expect an alpine greenhouse is in my future, to deal with the above  
issues, glazed with something very sturdy.
Near the mouth of the Columbia River on the Pacific Ocean, where  
today it was clear, sunny, and above 60F. Snowdrops and crocus are  
flowering in my garden.

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