Posted: 13/04/2014 at 09:04
The pot size doesn't matter. They're suffering from insufficient bright light. While the windowsill appears to be a light spot, you can see the seedlings leaning desperately towards the window in search of more light. That's the tell-tale sign.
Mark, you can get away without a greenhouse at this stage. All you need is a naturally sunny outside area. Get one of those small plastic or wooden crates from a greengrocer, place the pots into it, and park them outside in direct sunlight. If daytime temps are down to single figures, cover the crate in some clear plastic or bubble wrap. A mini-greenhouse. Leave them out as long as possible, to get as much sun as possible, bring them inside overnight.
The longer you leave them where they are, the more their future is compromised. Oh, and lay off watering them, too. Let the mix dry out between waterings.