Hi kulan hunter, thanks for the comments. You're spot on, 2.5 gallons = about 10 litres. They look big enough to me too. If what fdd2blk is correct, and looking closely at the leaves tonight I think more and more that he is, then it's because I've had them literally baking in direct sunlight almost every day for the last two weeks. If the sun moves, I move the plants so they get no relief at all. What's more, they're in black pots at the moment so it could be the roots are suffering which wouldn't help the plants to feed properly.
I have a spot in the back which used to have a herb garden and I cleared it out recently. It gets "direct" sunlight for only half the day, and for the rest it is either partly shaded by a palm tree or totally shaded by the house. If this weather contiues I think it may be better to set them there in the meantime to give them a chance to recover. However rain is forecast for the rest of the week, so could be the end of our Summer which will, of course, give me more problems LOL. Also I now have four Purple Power seedlings on the go and, believe it or not, femaleseeds.nl who developed them say they respond to low light levels so can be grown in the shade (they were specially developed to grow in colder, wetter climates), so I was reserving the herb garden spot for them.
Am even considering setting up a growroom in the shed, which would be perfect for it, but money is an issue and no electricity so I'd have to bring my cousin (a spark) into my confidence. He's definitely trustworthy, but it's something I'd rather not have to do. The house is out of the question though, and I'd also kinda feel I was giving up if you know what I mean.
Anyway, I have my babies in the house tonight under a florescent light just to keep a close eye on them while I consider what to do next. The smell is pretty strong LOL, although they still have a fresh mint sort of aroma, so not too "dangerous" just yet.
Sorry for such a long post, just worried about them I think ...
green.