My firm belief is that the biggest potential for sub-irrigated growing is to convert the millions of traditional drain hole pots that are currently in use to sub-irrigated planters (SIPs - aka erroneously as "self-watering"). There is no real need to buy special "self-watering" planters.
These photos are from Johanne Daoust's Flickr photo set. The first one shows her initial method of SIP conversion. It employs a water/oxygen reservoir, fill tube, plastic liner and overflow drain hole tube.
The problem with this method is the need to drill a hole in the ceramic pot. This requires a carbide or diamond drill bit and is a laborious task if you are converting many pots.
Johanne designed a very clever workaround that is easy to do and does not require a drill. The second photo explains the method.
The reservoir at the bottom of the pot is covered with landscape fabric to prevent soil particles entering the reservoir and inhibits the roots from clogging it. To avoid leaks she also used heavier duty plastic in place of the thin sheet plastic used in the first version.
The key feature, however, is the way she designed the overflow drainage. It is simple but effective and avoids the need for drilling.
Instead of drilling through the sidewall of the pot, she simply made some holes in the sheet plastic at the height of the reservoir. To maintain a space for overflow drainage, she wedged some pieces of drainpipe between the plastic and wall of the pot. Overflow drainage will flow through this space down to the bottom of the pot and out the drain hole.
Note that she refers to “weeping tile”. This is a name used in Canada for plastic corrugated drainpipe. My guess is that it originates from the fact that drainpipe was originally made from clay as in clay tile. Also disregard the clay pebbles at the bottom. They are not necessary and she did not use them when she planted the pots.
I will make and photograph a planter like this to further illustrate the method. This method appears to be a winner! We need many more growers like Johanne who create new ways to design SIPs that are simple but effective. Stay tuned.