Horticultural grade vermiculite

14 years ago

Hi All,

I purchased vermiculite for my first square foot garden. I had a tough time locating a source that carried it in 4 cf bags. Now I'm worried because I read a post from someone who stated that they bought the wrong vermiculite. Can someone ease my worry? Is horticultural grade acceptable for Mel's mix? On the package, neither coarse or medium is checked off, but in perm marker, someone wrote "VC". I assumed that to mean vermiculite - coarse. Help.

Kim

Featured Answer

Georg Rauh

8 years ago

last modified: 8 years ago

Vermiculite comes in different grades from micro to coarse, and it depends what you want to do with it in your garden. If you want to mix it with, say perlite for large plants in Hydro, a grade of vermiculite where the grains are as big as typical perlite (3,4,5mm etc.) would probably be best. For seeds or for seedlings, a finer grade would be better, say as fine as sand or a little coarser. More coarse means more aeration at the roots and better drainage but less water retention. I had a bag of vermiculite which was very coarse with some chunks exceeding 1cm (1/2"), Plant!t brand, which I found perfect for my uses, so I bought a 100L bulk sack (local brand) and found the new vermiculite way too fine for my uses. Yes, too bad a lot of vendors dont specify what grade the vermiculite is, they show you a stock image on their site and the actual product might look different. Now I have "grade 3" coming and hope it's the right one. As for "horticultural", I think this refers to whether there are any impurities in the vermiculite, some call the fine one "horticultural" and others the coarse one.

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Comments (10)

luke3026
14 years ago
I think "VC" might mean "very course." But either way, I think your stuff will work fine. Horticultural grade means safe for plant cultivation so that stuff is the right stuff. This is only my second year of SFG, so maybe someone more experienced can chime in if I'm wrong.

Here is a link that might be useful: Garden blog
angela12345
14 years ago
Horticultural grade is good. Although, not necessary depending on the vermiculite manufacturer, the same exact contents may be packaged into different bags for different marketing/applications. My bags did not say the particle size either, so I looked up the manufacturer on the internet from the bag and called them to find out the size. For the manufacturer that distributes in this area, their horticultural grade comes in coarse & medium.
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thinkstoomuch
Original Author
14 years ago
Thanks for the replies. I feel better. I might contact the manufacturer just out of curiousity.
curt_grow
14 years ago
Kim; From what I understand Horticultural grade = coarse and what Mel recommends in his book.That's what I used and it came from the local green house (what they use). Feeling better now?

Curt :-)
thinkstoomuch
Original Author
14 years ago
I do feel better now. Thank you!
angela12345
14 years ago
Sorry, don't mean to be disagreeable, but our area horticultural vermiculite comes in medium & coarse ... http://palmettovermiculite.com/products.html

Although, I used medium last year and it was ok.
curt_grow
14 years ago
Not a problem for me angela. Thank you for clearing that up.

Curt :)
joe LeGrand
3 years ago
I was told to use stall refresher, it is the same as garden vermiculite & it is much cheaper.

Example:

https://www.tractorsupply.com/tsc/product/sweet-pdz-stall-refresher-25-lb-5065990?cm_mmc=feed--GoogleShopping--Product-_-5065990&gclid=Cj0KCQjwgtWDBhDZARIsADEKwgPZ-1a1V7OmY-D5XrU2Bx8ahlNnjnvFxhex
Kathryn Dailey
last month
last modified: last month
PDZ is zeolite. here is a paper stating the difference between it and vermiculite in garden soil. I use zeolite as litter box type material under my chicken coop roosts. It is compostable. I wouldn’t use it as a complete substitute for Vermiculite, but mixing some in to make the mix cheaper seems like a reasonable plan.

https://www.proquest.com/openview/bbb0b91b2038d1d595b59f35b6435184/1?pq-origsite=gscholar&cbl=2032440#:~:text=This%20means%20that%20zeolite%20is,micronutrient%20availability%20(especially%20Fe).