Ray ) wrote:
: Dave,

: You need to think about Aaron's "shrink and grow" comment. I think it's a bad idea under a plant or
: pad of moss.

Yeah, I have been thinking about that. I bought some of this stuff to play
around with but I haven't actually used it on a plant yet. The stuff expands
a *lot* when you soak it in water. But, it doesn't soak up water and expand
very quickly so in practice I wonder how much expansion you're really going
to see. Unless you soak the plant in water for quite awhile (a practice which
I don't follow) there's not going to be enough water available for long
enough to allow for maximum expansion. Given that you gotta start wondering
if there's any benefit. Remember, I'm only looking for a day or two more
water retention so maybe it will be enough. It's time for another experiment
methinks. I think I'll spread some crystals over a bed of damp sphagnum and
see how much water it absorbs over time. That should give some indication of
how it will behave in real conditions.

Dave

: --

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

: . . . . . . . . . . .
: "Dave Sheehy" wrote in message
: ...
: Aaron Hicks ) wrote:
: : These compounds (polyacrylamide and polyacrylate polymers) go by
: : the generic name "superabsorbent polymers," or SAPs. They can hold several
: : hundred times their own weight in water. The ones featured are probably
: : the potassium polyacrylate polyacrylamide copolymer.
:
: snip
:
: : While they may have certain limited applications in agriculture,
: : their use with orchids is minimal. These cystals expand and contract as
: : they absorb or release water, so they shrink and grow. The net upshot is
: : that anything that does so will eventually wash out of your bark media and
: : onto your greenhouse floor (don't slip on 'em). For epiphytic species that
: : require lots of air circulation, this renders them useless. Even if they
: : could be retained within the media, epiphytic orchids generally die from
: : too much water, rather than not enough. SAPs in this context would prove
: : to be counterproductive.
:
: snip
:
: : I just don't see the upside to using SAPs with orchids. If anyone
: : has one that can beat (pound per pound) stuff like sphagnum, I'd sure like
: : to hear it.
:
: Here's an application of this stuff that I've been considering. I grow
: indoors in a window sill. A number of those are mounted orchids that
: hang in the window sill. I've packed all those orchids with wads of sphagnum
: in order maximize moisture retention. Even at that they still dry out
: within a day or maybe two. For some types of orchids (e.g. Cirrhopetalum,
: Encyclia, and Brassia) I'd like to get this up to 3 or 4 days (not sopping
: wet but ideally somewhat damp). My thought is to incorporate this material
: inside or underneath the sphagnum wad with the idea being that the polymer
: will release its moisture and keep the sphagnum hydrated.
:
: I do worry about how well the sphagnum will retain this stuff and how the
: cyclic shrinking and growing will hold up.
:
: Dave Sheehy
: