I wrote about creating water wicking boxes here:
They’re going very well. I’ve now got 3 down the back and 3 up on the house deck. Apart from keeping the seeds damp until they germinated, no extra water has been added to the boxes, although the 3 down the back have had some rain on them. So far I’m pretty happy with the idea, but as I said in the original post, summer will be the real test.
Wicking box with Bok Choy