Good Pet Stores usually have cork rounds and I cut them down to the sizes I need. If you order online its hit or miss as to what the cork round looks like in size and how open the hole going through the round is.

You might also be able to get them from a larger florist.

I also did similar with other plants and just get the round down into the substrate. I used some of the soil that came with the plant when I stuck them into the round and then covered that with some plantation soil.


Here is two pics of a round and then with stuff in and on it.