There is no size of the vermiculite on the bags I use. I use the vermiculite that is usually sold as insulation at stores that sell building materials, so it is not really fine. The size of the vermiculite I use, varies from 3 mm to 6 mm. It doesn't matter if tiny seeds fall a bit deeper, they still will get enough light. The vermiculite doesn't weigh much, so the seeds won't have much troubles to fight their way to the surface.
@RickCorey : you can take direct quotes from my website as much as you want.
