Hi Eric

I have a greenhouse that regularly gets over 38°C (100°F) during summer.
Because of last year's drought we were on water restrictions able to only
water the garden between 6 and 8 in the morning two days a week and fixed
sprinkler systems were banned. I increased the shade cloth cover for the
sensitive plants but the rest of the collection (about 550 species from
various growing regions both in pots and mounted) had to survive on what
water I could give them 2 days a week. I had a large garbage bin full of
water in the greenhouse into which I could dip the mounted plants and the
plants that needed more water and the fans were running continuously trying
to keep the conditions bearable. The water-dipping got quite tedious due to
the considerable number of mounted plants hanging around the collection but
it helped keep the humidity higher as the water dripped off onto the floor
of the house. (I topped up the bin on days I could water inside the
glasshouse.)

At the end of summer, I had not lost one plant. The new growth on a few of
the more thin-leafed, water/humidity loving species had developed accordion
leaves, but all survived the reduced watering and lower humidity. In fact
some of the plants did better on a more infrequent watering program. I know
I can be a bit heavy-handed on the watering at times so the drought had some
hidden benefits.

I was amazed by how hardy the plants were in general. I wouldn't recommend
these growing conditions but most orchids can tolerate adverse growing
conditions far better than most plants.

I just hope we get a lot of rain between now and the next summer season as
our dams are currently 38.5% full and the prospect of no water restrictions
are looking grim. I am currently looking at installing a rainwater tank as
insurance.

John

"Eric Hunt" wrote in message
...
Hi,

This is a problem that's been solved many times over - swamp coolers and
other devices can be used in hobby greenhouses to get the temps under 100.

Who out there has a greenhouse where the days regularly top 100? What do
you do? Do you just tailor your collection to grow plants you know can
take that level of heat? Do you have a misting system that keeps the
humidity really high? Plants can take the heat better with more water in
the air.

Sorry I can't be of much direct help - San Francisco is the natural cloud
forest of America, even in summer.

Good luck!

-Eric in SF
www.orchidphotos.org
www.plantworld.org