Good idea.
I started with just one bag; now I buy the huge bags. If you can find the horticultural type medium or coarse grade of Vermiculite it is better than the fine/small grade, but sometimes we have to buy whatever is available locally.
In some other countries where Vermiculite is not readily available they use rice hulls or coco fibers in the same way.
Here is a good link to show the Forsyth Pot method.
https://www.extension.umn.edu/...
