So, I was wondering what people use to plug the drain holes in their pots; not to keep water from escaping, but just to prevent spilling out the dirt. I'm about to make up several dozen (possibly hundred) of those plain black nursery pots in preparation to divide a number of overgrown colonies of clumping 'dews. Normally, I would lay a little LFS in the bottom of each pot to prevent my media from spilling out over time. However, I sometimes have problems with LFS rotting at the bottom of pots, and that aside plugging that many pots would be time-consuming and expensive with sphagnum. The next alternative I can think of is rough gravel, but I don't have a cheap, clean supply handy. Suggestions?