Mimi, this is a great tute. I really appreciate the link.
I'm a gardener and know about the plastic versions of stuff like vermiculite but didn't know there was a biodegradable version which could do the same thing but much more affordably. And, like the rice pack hotpads/coolers I've made and used in the past, these are biodegradable and usable and affordable!
I'm definitely adding these to my "to do" list.