It could simply be lack of water, where are you in the UK Blackgrass?

I am in tintagel, cornwall. I did`nt want to put them in growbags..take up too much room, so put them in pots in my small poly. I watewr them twice a day.

pots do look a little on the small side. We've got our toms in bigger pots in greenhouse with door and vents open. They stand three to a large tray and this is filled with water. Watering from the top means that the roots near the bottom of the plant may not be getting eough or even any water.

Thank you moon grower for your interesting & useful answer, much appreciated!

Your plants could be lacking in magnesium, as well, as they look a bit mottled and yellow, Blackgrass. You could give them a feed with magnesium sulphate (8 ounces in
2 1/2 gallons of water). You can also use Epsom salts, but I don't know the dosage. Also, if you stand the pots on the soil in the garden instead of concrete, the roots can expand into it, and then it wouldn't matter so much about the size of the pots. Hope that helps, Annie