Tomato plants turned blue

[littlemoney]

My tomato plants (Sungold and Sweet Million) are in my cold frame. I would normally have planted out in the garden by now but with the weather conditions of cold, wind and rain I have delayed this. The plants are turning blue. What has happened and will they recover. I am hoping to plant them out at the end of the week but don't know if they are a lost cause for a crop later this year.

I don't think the frost got them as I closed the cold frame when a possible frost was forecast but I have had the lid open in the day time after slowly hardening them off.

[Plot70]

I have put some in there final outside position. They were being held back by the cold during hardening off and the leaves had darkened.
They are under 5L cooking oil bottles and have put on some normal leaves and look like they will take off if we ever get some normal weather.

[ameno]

It's the cold which does it. Tomato plants turn purple when temperatures are too cold for them (which is anything much less than 10c).
They will recover once things warm up a bit, although this cold spell will have stalled them, and they'll likely take a week or two to get going again.

[Plot70]

Yes they will be fine.
I have got a canary without cover that has done nothing and some covered ones that have greened up.
Have a look.

[littlemoney]

Thanks for the comments. It seems that not all is lost and it will be worth the effort of planting out and looking after them.