Question
I have a 3 tier wall fountain I'd like to fill with greenery and/or flowers.  It does not have any drainage.  What is the first thing I should do before filling with soil and plants?  Any ideas on what to plant?  I live in Southern California.

Thank you.

Answer
This is going to be difficult to have the success you want to achieve. The two problems are drainage and soil depth. In a deep pot the drainage could be helped by placing pebbles at the bottom of the pot. But, there isn't enough room for that. Or you could drill holes for drainage.
Most plants will not do well if they can't get their roots down into the soil. If the soil is shallow it will also dry out quickly. If you place the fountain in light shade, this would help that problem and then you would have a selection of shallow plants like moss, or corsican mint (Latin name Mentha Requienii).
I know this is not what you had in mind, so my best advise is, do what I would do, experiment. Try small leaved, ground cover plants first. Such as allysum,  lobelia,  viola, or creeping Jenny. They will require some sun, so be prepared to water them.
If all else fails, there are beautiful silk plants that will look nice year around.

bakerplanter