The cut-up water bottle idea turns out to have a fault - it seems to confuse the plants by exposing the roots to some light, in our case anyway. Growing in see-through pots seems to hindered the plants' development after a certain stage. We started moving the chards into shop-bought flowerpots and they are instantly showing more will to live.
The radishes remain in the see-through vessels, because root vegetable don't usually like being transplanted. It looks like their roots will never turn into radishes though - but I'm still happy because they are growing a lot of big leaves and I've been wanting to try Steph's radish greens pesto idea since I've read about it. (I'll tell you how the pesto worked out next week.)
I've got some yellow blooms too which are all refugees from somewhere else. A few weeks ago we went to a big garden to help out with some jobs. I weeded the overgrown border while boyfriend cut down a very old apple tree. I saved some of the weeded-out flowering plants from the bin to give them a new home on our balcony. They took to the transplant very well.