11.   The pots must be clean and have drainage holes in the bottom.

12.   The pot should have drainage holes -- the more, the better.

13.   These small cuts will create four drainage holes at the floor of the finished birdhouse.

14.   This is a good move with any cached pot, since it will elevate the drainage hole.

15.   Use a clean clay pot with a drainage hole.

16.   You can plug any drainage holes with corks and silicone caulking and make porous containers watertight with sealant.