protected cold frame

Uli Urban
Tue, 20 Jan 2009 15:38:00 PST
Dear Jane,Dear Jim,

Obviously I did not follow all the contributions so it is the first time
I hear about your protected cold frame. It sounds most interesting and I
have had the idea to build something like this for many years in my
garden but have not yet done so.

It was most interesting to read about your cold frames and thank you for
the photos. I use a simpler  different version to cover two beds on the
base of my greenhouse wall: one for hardy cactus that need just
protection from winter rain and one for tender perennials and half-hardy
bulbs. It worked wonders last year but I do not yet know how the results
will be this very cold winter. Some of the foliage at least looks VERY
dead. I bought old commercial cold frame windows from a nursery,
replaced the glass with polycarbonate (Plexiglas) which allows
UV-spectrum rays through, is lightweight and will not break. These
windows are leaning at an angle of about 45° to the wall and allow the
wind to pass in order to avoid overheating on sunny days.

For opening mechanisms there are automatic vent controls that work
without electricity. I used several of them in my old greenhouse. Once
adjusted they work forever very reliably, many different models are on
the market, I think they were invented in England and use the
expansion/shrinking of hydraulic oil in changing temperatures which is
transmitted by cleverly designed levers to the windows that open and
close accordingly. Is much simpler and cheaper than motorized
thermostat-controlled ventilation.

YES, PLEASE re-publish the article on cold frames for us PBS-members!

greetings from Germany, recovering from one of the coldest periods
recorded......  Camellias and Trachycarpus alive (so far) Chamaerops
(experimental planting) and Sabal probably dead.          Uli

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