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From ddixon@ES.COM Mon Jun 10 14:09:07 1996
To: ahicks@nmt.edu
Subject: A new potting mix for orchids
Aaron,
You may have seen my posting to the rec.gardens.orchids news group last month
about ground up polyurethane foam as a medium for potting orchids. I am
including below a little more information and the reports that I have
received to date from the growers that I have testing it. Feel free to post
any/all of it to the FAQ. I am offering free samples of the foam and/or the
mix to people through July 1996. Let me know if you need more information.
Thanks
Darrell (ddixon@es.com)
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In 1993 I started experimenting with ground up polyurethane foam, (not the same
thing as Styrofoam), as an additive to peat based orchid potting mixes. By
fluffing up the mix with this 'fluffing agent', I was attempting to avoid some
of the problems that many people experience with peat-based mixes.
A word of caution here: Urethane comes in a number different formulas. The
only one that I can vouch for is the one that I have been testing. I have
talked to the manufacturer of the foam and they tell me that they believe it
is safe for a horticulture use. It is listed as bio-stable and is not expected
to break down chemically with time and exposure. It is listed as safe for
landfill disposal.
The mix that I settled on is composed of by volume, 50% fluffing agent, 25%
peat and 25% a commercially available general purpose potting soil (not
intended for orchids). The general purpose potting soil contains fine
particles of various types of bark, peat, sand and other things. (The fluffing
agent keeps these fine particles separated so that they do not clump.)
This formula gives a mix with the following characteristics:
. Is very light, soft and fluffy
. Does not compress when wet
. Does not cake when dry
. Easy to rewet when dry
. Holds water and air well
. Seems to respond well to the same systematic watering schedule that is
usually follow with plants in bark
I pot with the straight mix or combine it with bark or lava rock. So far, I
have had good success with all methods on both seedlings and mature plants.
About 9 months ago, I starting sending some of the potting mix and some of the
fluffing agent out to selected commercial growers around the country for
testing. These tests have had mostly positive results to this point. I would
now like to promote the testing of this material by others by doing the
following:
. I am making the reports from five current testers available.
. Through July 1996, I am making free sample of both the peat-based mix and
the fluffing agent available.
I can be contact at ddixon@es.com
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Reports from 5 testers:
************************
Tester #1:
Date: Wed, 20 Dec 1995
The mix arrived yesterday. Weird looking stuff isn't it - I will be
using it over the next couple weeks and will then monitor the results.
Date: Thu, 30 May 1996
Sorry I haven't gotten back to you with any results, but I really
wanted to give it a little more time. With so many mixes here in the
humidity, (like NZ spag) everything will look great for a few months,
and then boom, the roots are gone! I have tried a lot of different
peat based mixes also and have had the same experience. If one doesn't
fungicide weekly (and I don't), then caution is the word. Just for
your information, I have compots, paphs, and phals planted in the
stuff. I should know a lot more about 1/2 way through our soggy
summer!
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Tester #2:
Date: Mon, 18 Dec 1995
The new material looks very interesting through the bag (haven't opened
it yet), and I got a "OH no! rock wool" initial reaction. I am not
thrilled by rock wool - stays too wet, but will let you know more when I
experiment. More "feeling-up" the bag really did show the silkiness...
very interesting.
Date: Tue, 09 Jan 1996
Well, let's see: am trying a couple of paphs in the pre-mixed blend, and
have concocted a phal mix with 33% each (your fluff)/spongerock/charcoal.
So far, so good. Doesn't stay soppy like rock wool...
Date: Mon, 04 Mar 1996
I really like the "pure" stuff when added to my spongerock/charcoal mix
for seedlings. The mix you made up with the soil is probably fine, but
I prefer the other, as it doesn't seem to compact as much.
Date: Tue, 09 Apr 1996
Have you considered a fluffer/rock wool mix? I have a 50/50 mix I've
been playing with in a large baggie, and - although a bear to mix - it
might work out well as a medium.
Also... is the material degradable in any way? (bio- or "geo-" like
rockwool or perlite) I'm curious as to disposal...
Note added by Darrell: The material is considered bio-stable. It is not
expected to break down chemically with time and
exposure. With prolonged exposure, it may break
down to smaller size particles. It is listed as
safe for landfill disposal.
Date: Tue, 21 May 1996
I have had great success with Phals using Cottonwood Mix-ULD to which
I've added about 30% fine perlite/charcoal. I have similar results
when taking my coarse sponge-rock/charcoal mix, and blending in about
50% fluffer. The capillarity caused by the adjacent surfaces of the
flakes seems to help retain moisture over the plain, coarse mix.
The only negative I have seen is with phals in straight Cottonwood
Mix-ULD in small plastic pots...it remained too soppy. Larger pots
(hence surface area) seem to avoid that problem. I haven't tried it
myself, but maybe a bit more fluffer for small plastic pots???
Note added by Darrell: Sufficient drainage material in the bottom of the pot
seems to be necessary even in small pots. The material
seems to drain well if given the opportunity to do so.
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Tester #3:
Date: Tue, 8 Aug 1995
Started using your mix last night. As a (sort of) controlled experiment,
I took seedlings (Phals) out of compots and split them evenly between your
stuff and Pro-Mix (HP). I've only done half a flat of each so far, I'll
finish off even flats and put them in similar locations in my plantroom.
Observations so far. Your mix has a different feel than most mixes, very
'soft', almost oily, like potting in cloth almost. It is nice texture, and
I like that it doesn't stick to my hands like Pro-Mix. Very clean potting.
It does indeed wet down much more easily than Pro-Mix. It is a bit more
difficult to pot with, as it doesn't flow into the pot like the fine peat
mix, and it is very difficult to keep from packing it in. I assume that it
isn't supposed to be packed into the pot, so I left it loose. On watering I
am afraid that it will compact more, but time will tell. So far so good.
It looks good in the pots - if aesthetics has any value.
Note added by Darrell: The mix does not compact in the pot when watering.
Date: Sat, 26 Aug 1995
Everything seems to be growing fine in your mix. It is certainly easier to
water than Pro-mix.
Date: Mon, 4 Dec 1995
So far they seem to be doing just fine. Positives: Easy to water, doesn't
compress or wash out of the pot. Negatives: can't really think of any. The
plants in the foam seem to be just as happy or happier than the ones that I
have in seedling bark. Pretty similar to the ones in Pro-mix. We shall see
how they make it through the winter. Actually they don't dry out as fast as
the Pro-mix, which is drying out a bit too fast for me to keep up with, that
would be another benefit.
Date: Wed, 3 Jan 1996
The seedlings I have in your mix are doing much better than the ones in
straight promix, and somewhat better than the ones in bark. As soon as I
get around to it I am going to switch all the pro-mix ones over to your mix.
Date: Fri, 5 Jan 1996
That mix of yours is nice for shipping, it stays nice and tight in the pot.
Date: Thu, 7 Mar 1996
Repoted all of the pro-mix seedlings a couple of days ago, they were running
at about 50% with good roots, and the remainder with few or no roots. That
is no good. Top growth is good in your mix, although over the winter the
plants in seedling bark seem to have given me the most top growth. Some of
the multiflorals are in spike, actually. I strive to grow the best roots
though (grow roots, rest follows), I have yet to see the difference between
bark roots and roots in your mix. I am going to try to finish that bench up
tonight, if all goes well, so I will let you know.
Date: Mon, 11 Mar 1996
Here is my report. Just (finally) repotted all my Phal seedlings.
Unfortunately for me, none of them lived up to expectation. After 6 months
in 2" pots, only about 8 needed potting up. Half really wanted to be potted
down due to root loss, so I did that. Some of them were just tossed.
So, with that in mind, I had half a flat of seedlings in your mix, half a
flat in pro-mix, and a full flat in bark. The Pro-mix was particularly
unpleasant, with high mortality and no plants performing well enough to be
moved to larger pots. So there. Your fluff mix did out perform the pro-mix,
however I was still not entirely satisfied. The roots certainly looked
better, but they were sparse. Under my conditions, the plants in your mix
that had done the best were the ones that had gotten an extra helping of
styrofoam peanuts for some reason. The ones with half peanuts, and your
mix on the top, were the best, not only of the plants in your mix, but
perhaps of all the plants. They certainly had the nicest roots.
Note added by Darrell: Sufficient drainage material in the bottom of the pot
seems to be necessary even in small pots. The material
seems to drain well if given the opportunity to do so.
Plants potted in seedling bark were disappointing. When I went to repot,
I realized that most of them had been there for over a year. That would
explain why they had better top growth, they had been there longer. Why
I hadn't repotted them earlier I do not know. As a consequence of not
repotting, most of these had substandard roots, as the mix was mostly or
completely broken down in most pots.
So, what did I learn? 1) Your mix performs better with at least half the
pot filled with styrofoam peanuts (I am not particularly surprised).
2) Pro-mix sucks for seedlings under my conditions.
I would use your mix again for seedlings, now that I have figured out the
tricks to it. I would certainly use your mix before Pro-mix, and seedling
bark.
I am tinkering a bit with different formulations. I think that a 50-50 mix
of your fluff with pro-mix might be superior to standard pro-mix. Come to
think of it, some of the fluff in the chunky peat mix might be a good idea
too, as it isn't terribly wettable. I have only a couple of plants in the
promix/fluff, I'll let you know how that turns out.
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Tester #4:
Date: Wed, 3 Jan 1996
We like the way the mix takes in water. No clumping like most mud mixes.
Promix is a good example. It seems to dry well though we'll see how it
goes. We have some phal seedlings going. Some paph compots. Some catt
seedlings. Some catt compots. Probably a few others, but we need a wider
range to work on and need to see what will constitute abuse and what the
plants will tolerate. The mix is sometimes added to other material. Fine
fir mix for catts and such ensures, hopefully, that the mix won't clump
around the roots. We made a few batches with Promix. Didn't wet as evenly
with 75% Promix and 25% fluff.
I've been testing the fluff. Less than satisfactory, or maybe I'm
just impatient, but I have a hellofa time getting it broken up. Wet is
easier than dry but I still wind up with clumps of it.
Note added by Darrell: The fluffing agent can be a little tricky to get
mixed into another material. The process that I
use is to put the fluff on top, in a layer 1-2
inches thick. Make sure that large chunks have
been broken into about quarter size and rub with
the open hand. I actually do this twice, rubbing
in half of the fluff, mixing up the resulting mix,
rubbing in the second half of the fluff and then
mixing it all up again.
Date: Thu, 4 Jan 1996
Phrags are the next victims, plus I want to see just how small various
genera can be potted out and still survive. Our normal initial potting
out mixes aren't too good in this regard, forcing us to keep stuff in
compot longer than we'd like. Catasetums are on the list, as are
Sophronitis and Cadetia.
Date: Mon, 4 Mar 1996
Only two negatives that I can see, and they aren't serious. One, if you
allow the stuff to dry in pot, it may "Blow Away" when hit with a forceful
mist..(So turn it down right?) The other is that it needs to be on the top
shelf, or at least not be below other plants. Drainage from above will dig
pretty good sized holes into it..other than that, it's great, especially
for potting out the real youngsters that bitch if they dry out..:)
Note added by Darrell: To avoid this "blow away" and "wash out", it is
probably a good idea to use a top dressing of bark
or something similar.
Date: Tue, 21 May 1996
Nothing significant to report. As with my last message to you, the only
problem that I can see is that top dressing the mix is probably a good
idea or your run the risk of digging holes in the media when watering.
Plants that we're growing in it are doing well.
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Tester #5:
Date: Tue, 26 Dec 1995
Received your mix today. I have potted up 10 Phrag longifolium seedlings in
your peat mix , and will compare their growth over time to 20 others potted
in our standard Phrag mix (10) and our standard Paph seedling mix (10). At
first blush, I note that the peat mix lacks "body", and the seedlings are
not well "anchored" in the mix upon potting- they wobble. . I think your
remaining peat mix will be combined with seedling grade fir bark @ 75% bark +
25% peat mix, as well as other combinations.
Date: Mon, 04 Mar 1996
So far, your mix works at least as well as our current `favorite'. I think it
will take another 3-4 months to be definitive.
Date: Wed, 20 Mar 1996
Phrag besseae definitely does not like the new mix !
Date: Thu, 21 Mar 1996
Phrag besseae is more sensitive to mix pH than other Phrags. I haven't done
a mix pH yet, but I would bet it's higher than 7.5. For some reason, a more
alkaline pH increases susceptibility of P. besseae to erwinia infection,
especially at the leaf axil, and this is what we are seeing. The other
Phrags appear to be OK so far.
Date: Wed, 22 May 1996
The stuff is deadly to Phrag besseae and it's hybrids. The Phrag
longifoliums will grow in it, but no better than our current bark
based mix.
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