Crocks or Paper

[Aiko]

I only use something for my seedlings. Just a layer of pebbles / grit. The same I use to mix with my soil (loam, mostly).

I am used to put my seedlings in a tray of water to water them. As I use loam for my mix, loam has the tendency to turn into a soft smush. If I would take out the pots from the tray of water, there is a risk the loam on the bottom of the pot will wash away along with the excess water. After a few times there will be a high risk of a cave in, and suddenly the entire contents of the pot along with all the seedlings will wash away. Just a layer of pebbles / grit prevents this.

For bigger plants that get a normal watering I usually don't have anything on the bottom, although sometimes still the same layer of pebbles / grit just to be sure.

[daniel82]

I'm in the never bothered covering the holes camp too. Never seem to have ever had any issues.

[el48tel]

Damp compost for me. My grandad warned of paper harbouring insect lavae.