Our big hurdle is limited time to maintain the garden, and the concern that we would kill the plants. To help with this, we decided it would be prudent to set up an auto-watering system, and although "Earth-Box" and similar autowatering pots looked effective, we wanted something a bit nicer looking, and much more to our (and our dining rooms) design style.
Note: this was to retrofit our pot (that had drain holes) to be self-watering, however, the tub could be used without the pot, and the same principles would work on any container.
Step 1: Materials & Design
Bowl to fit pot (Size 14) - $4.35
Flexible tub (55 gallon) - $4.98 could be any waterproof pot/garden tub that fits snugly in the pot.
Net Pot - $0.75
3/4" Irrigation Pipe - $0.90
Strong Waterproof Tape (I used Duct Tape)
Hand Saw (to cut pipe)
Step 2: Build Insert
Cut a hole to the side of the net pot to snugly insert the irrigation pipe into.
Dry fit all pieces of the system together, and cut pipe so that it extends an inch or two through the bowl, and an inch or two higher than your pot edge (I didn't get a picture of this step.)
Insert your net pot and pipe, and tape to prevent sliding of any parts. Pipe should only go through the bowl slightly.
Step 3: Finishing Steps
The tub sets right into the large pot, and with it's top lid below the rim. I left the handles on, as they make it convenient if I want to carry the tub outside to refill with dirt, etc, and should be hidden by the plants anyways.
Fill the tub with water until it's full to the bottom of the bowl.
Fill the pot with potting soil, making sure to push the potting soil into the net pot at the base. This will act as a wick, and allow your plants to pull water into the soil as they need.
From this point forward, you should just need to fill the plant through the fill pipe, and let the plants water themselves. You could easily mix in some plant food into the water, and it would help pull keep the plants healthy as well.
I still plan on making a small float to drop into the pipe that will show us the water level in the pot.