Perlite substitute

Mary Sue Ittner
Tue, 04 Jul 2006 20:53:05 PDT

I find it interesting when we revisit this subject every now and then. What 
I've noticed is that we are such a diverse group from so many climates and 
situations that what works one place does not seem to work as well other 
places. In the beginning of my bulb addiction I tried whatever anyone 
suggested. Perlite made me cough so I abandoned it.  Someone recommended 
cat litter once. I tried it unsuccessfully ( I did look for one without a 
lot of additives.) I searched everywhere for Turface, calling around and 
finally found some that I could purchase I think as Profile clay soil 
conditioner or perhaps it was aquarium mix. Nothing has ever grown very 
well for me in it so I've stopped looking for it. Someone recommended 
decomposed granite so I got a bag of it at a landscape supply store. It was 
so heavy and clumped too and in my wet winters I'm sure did not generate 
the air porosity I needed. Red lava rock easily obtained in Northern 
California was not a success either although I think in a bed where I mixed 
it in bulbs may have done better in later years so perhaps the rain leached 
something out that was not good in the beginning. When I first started 
growing bulbs I read that 1/2 sand and 1/2 peat moss was very good. So I 
bought sand and didn't realize it needed to be coarse. The definition of 
"sand" to me was what you had in your sandbox as a child or saw at the 
ocean. I am sure what I added to my mix resulted in less air in the mix 
instead of more. I never could find grit when I was looking for it when 
everyone talked of adding grit to the top of their pots. What I use now is 
coarse sand (which is like small pebbles or rocks) easily obtained at 
landscape stores  and even available here away from civilization and pumice 
which I can get in bags at Orchard Supply and a place called Harmony Supply 
in Sebastopol. Those places are a couple hours away so we buy a lot of bags 
when we go. And it isn't cheap either. You can also get it at Charley's 
Greenhouse Supply  but it is even more expensive there (although in 
different grades.) What I'm looking for is something to add air porosity to 
my mixes during my main growing season when it rains a lot and temperatures 
are cool. Most of the bulbs in my collection are winter growers. Sometimes 
I add fir bark or even redwood compost and a handful of coir too even 
though I've been told that the salt content in it can be very damaging for 
some plants.  I loved Bob Werra's description of his Moraea mix when he 
asked and answered the rhetorical question about why he used what he did 
with, "just because." There are a lot of ways to grow bulbs and if you keep 
trying you find what works for you. I seem to recall John Lonsdale who 
brought up this whole subject telling us he used composted peanut hulls 
with his perlite and that obviously isn't something easily obtainable here. 
I'm don't mean to discourage all the suggestions since it is fascinating to 
hear what works in different places, but since we probably have all levels 
of experience in our group would like to point out to the beginners in our 
group that additives are often used to create air spaces in your mix so the 
bulbs won't rot and to do that the particles have to be different sizes. 
That's why perlite when it gets to be mostly fines or fine sand is a 
problem. Using some of these things can create bog conditions with very 
little air.

Mary Sue

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