On 17 Jul 2003 22:48:18 -0700, (Lil) wrote in
Message-Id: :

After a week growing orchids outside in Napa, I noticed that some of
the orchids were developing straw-colored patches that kind of the
same color as ripe corn.

If the patches are the color of white corn, it is likely that those
areas will die. If the patches are the color of yellow corn, there is
a possibility that the plant will recover its more normal green color
over several weeks if removed from the overly bright conditions.

Are they burn patches, where the part of the plant may have had some
direct sun-exposure?

That would be my guess.

Will the plants recover? (I've moved them back
inside where temperatures don't fluctuate as much. I noticed that the
temperatures have a 30 degree range outside. ranging from 60's to
90's.) Any ideas on how I can resuscitate the orchids will be greatly
appreciated.

All but the very light leaf areas should eventually recover when
placed in a shadier location.

When moving orchid plants from indoors to outside it is important to
"harden" the plants. This is accomplished by making the changes in
light and temperature gradually over several days. Plants that are
able to withstand direct sun light will burn if not progressively
acclimatized to it.

You don't mention the genera with which you are working, but if they
are incapable of withstanding full sun all day, there are two
parameters to consider manipulating: light intensity and exposure
duration.

The high intensity of sun light may be moderated with shade cloth.
Covering a patio with beige 70% shade cloth should accommodate most
orchids needs well without being unsightly.

Many plants can withstand direct sun light without damage for periods
up to several hours, but burn if exposed all day long. The duration
the plant receives direct/bright light can be reduced by placing it in
an eastern exposure, or under other foliage to provide more dappled
lighting conditions. Microclimate is everything.