I'm a complete newbie when it comes to gardening and am trying to start a
plot using the concepts of www.squarefootgardening.com. He suggests a
mixture of 1/3 peat moss, 1/3 coarse vermiculite and 1/3 compost. Problem
is I can't find the vermiculite and the guy at our local garden center says
it's because it's now illegal. I did some research on this group and see
that it's been discussed extensively but couldn't find any suggested
alternatives. What else would you put into this mixture if you couldn't
find vermiculite? In case it matters, I'm in zone 6a and am planning on
planting tomatoes, peppers, beets, arugula, basil, parsley, peas and beans.
Thanks for any advice you can offer!
I've always found perlite to be useful in applications similar to this.
BTW vermiculite is NOT ILLEGAL but it seems that some of the ill-informed
have decided that since vermiculite from one location in the US had some
asbestos in it that all vermiculite must be dangerous and that the sky is
falling and refuse to have anything to do with it no matter the source. If
you can find a vendor with the intelligence to know the difference you
should have no trouble buying vermiculite.
I agree about the perlite. But asbestus litigation is a growing industry,
and with number of companies with deep pockets and actual liability
concerns dwindling, the lawyers are going after anyone who can even spell
"asbestus". I wouldn't sell vermiculite, even from a certified asbestus
free supplier; I don't an unscrupulous lawyer breathing down my neck 20
years from now when some gardener (who may or may not have been my
customer) gets mesothelioma and starts suing garden centers that
once-upon-a-time sold vermiculite.
Okay, so it seems I just need to find the stuff somewhere. One problem I'm
having is that every source seems to sell it in a different measure, so
pounds one place, quarts or liters somewhere else. I'm looking for 3 or 4
cubic feet. Does anyone know how many pounds of vermiculite is in a cubic
foot? I think 4 cubic feet comes to just over 100 quarts which is a heck of
a lot of those little 8 quart bags they have at the one local store I found
which carries vermiculite. Does anyone have a trusty online source they've
For the record, I'm planning on a 5x3 8" tall raised bed. I've bought 3.8
cubic feet of peat moss and I'm hoping to get about the same amount of
compost from the city (Boston) along with slightly less vermiculite wherever
I can find (and afford) it. Does this sound about right or am I totally
barking up the wrong tree? If I don't end up finding the vermiculite, I was
thinking of suplementing with something else (some kind of soil?) and just
throwing in a small amount of the perlite. What do you think?
Thanks for all your advice!
Another question about square foot gardening; I noticed that watering is
very crucial as there is no place to the excess water to go. Does one have
to cover the plants when it rains to prevent root rot?
Okay, from my research into this vermiculite problem, it's the stuff they get
from Africa, not our local vermiculite which is the problem. However, lava sand
is a much more effective product, if you can find it.
Skip the Mell soils and follow this link
Lots of great mixes without Vermiculite
Buy vermiculite from a Home Depot and save lots of $$$$ if you MUST
Acts of creation are ordinarily reserved for gods and poets. To plant a pine,
one need only own a shovel.
-- Aldo Leopold
So is the vermiculte only used to "lighten" the mix or does it add some
specific nutrient that might be missing if I use sand or whatever? Where do
you get decomposed granite sand? Is that something that is sold
specifically for gardening or can I get it at any old hardware store?
Vermiculite is inert, has no nutritive value to speak of and is used merely by
the greenhouse industry as a potting medium and seed germination product. It is
used because it is very lightweight and deliveries are easier and trucks can
Compost is the nutritive value in soil structure, not the hard substances like
sands of any kind. I buy lavasand or crushed or decomposed granite in Home
Depot or Lowes. I don't know where you live or what your local retailers sell,
which is why plain play sand is also good to take up space and help drainage. I
don't know anyone who uses vermiculite in the soil, just in pots.
Vermiculite is a mica-like mineral. When heated, the laminae break apart
and the mineral expands, which makes it light and also makes it able to
hold water. The primary value in growing media is its water holding
capacity, coupled with improved drainage. That sounds contradictory, but
it's not. The water is held in the vermiculite particles, but the
particles are large, creating spaces in the medium between the particles
through which excess water can travel for drainage. Since roots need
both water and air, vermiculite is a valuable addition for starting
plants. I believe the basic composition is related to silica, so it has
no significant nutritive qualities.
As a mineral, it is extracted from mines.
See my potting mix recipe at
<http://www.rossde.com/garden/garden_potting_mix.html . The
necessary texture -- drainage, aeration, moisture availability --
is provided by the sand and peat. You only need a little compost
(real, not some commercial potting mix) to provide the friendly
soil bacteria that release the nutrients.
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