Manelli Family: It's the "cover overhead" that Bill objects to, and he has
some very valid points, altho there are other issues to consider.

The cover overhead increases solar loading, and therefore heat inside the
shadehouse, even when all the sides are open. This is inescapable, short of
ditching the roof, and it causes me not to grow anything but the most
heat-tolerant orchids -- unless they are cold-hardy enough to stay out all
winter in the one "uncovered" shadehouse that we have -- we are too busy to
be carting plants in and out all the time during winter, which is our
busiest sales season). And I do have to take some measures to cool things
down (exhaust fans and overhead misters) in summer, which does make FPL
happy.

But without it:

1. It is indeed very difficult to heat for winter -- and yes, we have to do
that here, at least enough so I DO notice the gas bill. We heat to 55F for
our vandas, evergreen dendrobiums, and buds on all genera that we grow (not
a concern for Bill given his specialization in the intergeneric Oncids, few
of which would complain at high 30s, but do hate high heat). With a small
shadehouse in the home setting, this may not be as much of a priority -- you
could roll out a sheet of plastic as needed and tie it down, or even bring
the tender stuff into the house at need. That's what we used to do when we
were growing in a 15' x 15' "hobbyhouse" less than 12' tall. We had it set
up much like opening or closing the drapes in one's home. We also had a
heating element that fit on the type of small propane tank that one uses for
a BBQ grill, and only needed one for the whole little house. Those
measures don't work so well with a much taller 10K sq. ft. to cover and
uncover.

2. You cannot control your watering. Where I am (a little over an hour
south of Bill), we get periods in summer where it rains quite heavily every
day for 2-3 weeks in a row. Some orchids like that, some will tolerate it
if you spray enough fungicide, and some just plain won't. [Aother point not
applicable to you home growers, but in a retail setting, you're also
effectively closed for business when it rains ... ].

Even in the home setting, whether or not to use the overhead cover depends
to a large extent on what you choose to grow, how you pot or mount them, and
other factors. This is something we discuss at length whenever customers
ask us to build a home shadehouse for them, to try to help them make an
informed decision.

Kenni


"Manelli Family" wrote in message
...

I wouldn't think anyone in a tropical climate would need or want a
greenhouse, even if they grew cacti. To protect them from the rain all
that would be needed is a cover overhead.