Hi there,
I purchased an automatic sprinkler system, that lets you add as many little feeder tubes off the main hose as I had pots, and more if I add more pots. I used the one from Gardenia:
http://www.gardena.com/uk/water-management/micro-drip-irrigation-system/ It is a micro-irrigation system and lets you feed very little amounts of water directly to the root of your plants, minimising water use. Also, drippers can be adjusted to release more or less water, depending on the needs of the plants, and season. Finally, a timer lets you adjust how many minutes a day you want to let the system run, so you can again adjust it for the season.
In addition, I found that using effective microorganisms (developed by Dr. Teruo Higa from Japan) is a natural and incredibly efficient way to get good soil organisms into your pots, and over time, these organisms help keep your soil alive and water absorbent. I discovered it takes a few years of using EM to really see the result, but then it suddenly became an exponential wow effect...just like all the books describe.
You can also add some biochar into your potting soil, if you spray it with EM1 before mixing it in, it helps the effective micro organisms develop faster, as well as adding soil carbon. The microbes also sequester carbon from the atmosphere into the soil, so that helps too.
What I would like to know, if there is a layering technique that could be used in pots, similar to the ones used in Hügelkultur or Raised Beds, that would help also?
Best, Diana