If you're not yet convinced that sub-irrigation is the way to grow plants in containers, read the customer reviews (see link below) about these sub-irrigation conversion kits (erroneously called "self-watering").
It's convenient to buy them, but you can easily do it yourself using recycled materials. This is just one of many posts that shows how to do it. Also, look at Johanne Daoust's Flickr photos. She shows how she converted her entire rooftop garden, including round pots and raised beds.
via www.gardeners.com Click on the "Reviews" link at the top. It's right under the heading.

I discovered your site when trying to find a system to help reduce watering in my garden, and have recently completed three sub-irrigated raised beds based on the land drain system.
I'm looking for some options for containers now, and just discovered a range of sub-irrigation (or "self watering", as they also call it) conversion kits in the UK. I thought you may be interested in taking a look:
http://www.tricor.co.uk/mona.htm
http://www.green-tech.co.uk/products/urban-tree-hard-landscaping/tree-and-plant-irrigation
They can be used in containers, raised beds, or in the open.
They're a bit pricey for me, but look a good option if you can afford it, and don't want to take the DIY route.
Posted by: Luke Noel-Storr | June 11, 2012 at 05:03 AM