I'm looking for sources for vermiculite to try out a bit of square foot gardening this season. I found one at menards but it says it's for attic insulation. It also says there's no formaldehyde (which I guess is a little bit of a low bar for organic gardening) but is there any reason to think that I can't use this for making the "Mel's Mix"?

Seems like I need a lot of vermiculite to do it and this is one of my only local options.

  • What grade is it? Should be coarse. Also, older vermiculite used in insulation contained asbestos. Try hydroponics shop for alternatives. Mar 5 '18 at 3:26
  • I found a blog from 10 years ago where someone used this brand. They had a picture of it opened and it looked pretty course. Mar 5 '18 at 3:29

The mines that were responsible for supplying the asbestos contaminated vermiculite for home insulation were closed long ago so it's a problem for old home owners. I would suggest not recycling that vermiculite for SFG use.

Some USA big box stores do carry vermiculite but it's likely to be medium rather than coarse grade.

Home Depot vermiculite

and what you're after is the coarse grade as it holds more water. If they don't specify the grade, you can check by sizing. Look for 4-8 mm size or higher.

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Vermiculite , as I know it, is expanded mica, no asbestos . An inert mineral, Wikipedia must have some more information.

  • Opps ! I see on Wiki that years ago , asbestos was added to some vermiculite products. Mar 5 '18 at 16:10
  • Asbestos in home insulation vermiculite has been a huge problem. Mar 5 '18 at 17:59

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