My guess is that while the pH, per se, may be playing a role, the real issue
is that you're starving the plants.

Orchids get essentially no nutrition from the medium - until it decomposes
that is, and at that point it's time to repot! You must add nutrients via a
fertilizer. Additionally, as the transfer of nutrient ions is osmotic,
continuous watering with pure water may actually imbalance things
sufficiently to remove previously-absorbed nutrient ions from the plant.

Moreover. as pure water has no buffering capacity, the pH can fluctuate
wildly upon dissolution of the tiniest amount of material into it. Adding
fertilizer will buffer it and give you a stable pH in the root environment.
(Use one designed for pure water or you'll have to adjust the pH further.)

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Artwork, Books and Lots of Free Info!


"sandra" wrote in message
ups.com...
Hello Everyone,
I've been recently having some problems with some of my orchids, their
plant growth to be specific, they are growing smaller leaves, and I
know they're getting plenty of light because they're in a west window
with 2 40 watt 4 ft fixtures.
I water with distilled water, some of my plants are in bark, some of
them are in moss...I noticed the ones in moss and one in bark are only
having this problem...
I water with distilled water at 5.6-6.1....should the water be more
alcalinic to offset the acidity of the potting medium?
The potting medium despite being sphag is around 5.5
-Sandra