in theory geothermal energy ought to be able to heat a greenhouse. you bury
a few pipes down where temperatures are higher and circulate the water to a
radiator in the ghouse. I've only just started looking at this, but some
folk say temps a yard down are a constant 50 odd degrees regardless of air
temperature above, others tell me in the uk you'd have to dig much deeper.
Anyone know anything about this? I'm sorely tempted to try an experiment
cheers
Jon


"Douglas" wrote in message
...

"Martin Brown" wrote in message
...
In message , Franz Heymann
writes

"Douglas" wrote in message
...

[snip]

When the temp reaches zero it freezes water. That
boy a the back pay attention! -What has a plant got in its stem ?.

A solution of various chemicals in water with a freezing point below
that of pure water.
Consider anti-freeze.

That is true, and some cold hardy cacti can be protected from several
degrees of dry frost provided that they are nicely desiccated and kept
dry with a thick sugary sap. Ironically some of the hardest cacti to
grow in the UK are also nominally cold hardy but they also need zero
humidity.

However, there are plenty of exotic tender plants that will croak at
temperatures even above 5-10C. Many succulent euphorbias and plants from
Madagascar are extremely temperature sensitive for instance.

Given the high cost of maintaining the entire greenhouse at elevated
temperatures most cactophiles I know keep a small warm box, a larger
chunk of greenhouse tepid and the rest only approximately frost free.

Regards,
--
Martin Brown

*********
Problem solved!. At last! - it's a dream come true. I'm going to be a
rich
man! (\:^)
I might sow some tomato seeds now to be ready for Christmas!. Imagine!,
freshly plucked chicken served with freshly plucked tomatoes, here in the
west of the north-western Lake District.. I'll make a fortune!.
All I need to know is the chemicals I have to mix into my watering can.
Ten percent for he who delivers the goods.
Doug.

********