Will sterile vermiculite harm worms?

by Rose Anne
(Orinda, California)

Is sterile vermiculite (Uni-Gro Vermiculite for indoor or outdoor)an ok addition to my worm farm??

The package also says it has slow-release potassium, magnesium and calcium.

I'm trying to lighten up my clay outside soil for a new tray in a flow system.

Thanks for your help.

Rose Anne

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Jul 16, 2013
Should You use Vermiculite In The Worm Bin?
by: Pauly

Hi Rose Anne,

I'm not a vermiculite user but it will not harm the worms. As you know vermiculite is an inorganic substance containing minerals.

Adding it to a worm bin though is something that is entirely up to you. Its benefit, for the most part, would be adding minerals to the castings.

If vermiculite does break up into tiny particles then it can also aid the worm in digesting food.

I'm just not experienced with this substance but don't see any harm in using it but there isn't a huge benefit either.

It actually might get in the way at times when you're wanting to distinguish certain things inside the bin as well as feeling gritty on your hands.

Don't think, though, that it will aid in the aerating of the bin. The worms already are the best at that. Casting are also great at holding in moisture as you know it takes a while for them to dry out.

Personally I would just leave it out and use it in the potting/starter mix but that's me.

All the best Rose Anne,

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