I've did this before a lot of times for the houseplants. Didn't work.

The reason being is that the soil itself becomes water logged, even tho' the two are not in direct contact, but connected with a piece of fabric, utilizing capillar action.

Molds and algae grow in the soil and the plant dies.

I think the only working self-watering system is a flood and drain one. With which I have no experience with, so I won't talk about.