Courgettes

I'm not having much luck with my courgettes. The first lot completely failed to germinate (I suspect it was too cold). The second batch germinated brilliantly and were looking really healthy until I potted them on, when they just seemed to shrivel up. Left with just 2 plants, I have planted up a new container (on special offer at the local plant nursery - so how could I refuse?).

The up-turned bottles were Sara's Mum's idea, having seen it done where they live in Greece. Since she mentioned this a few weeks ago I've seen it repeated in many places as a drought busting idea to encourage strong, deep roots. I've also reused the cut-off bottoms to act as propagators for six more seeds - I'm determined to harvest a few courgettes!!