tomato purple leaves

[truongthanh]

Can anyone help me figure this out? I noticed that the leaves of my tomato plants are turning purple. I'm not quite sure what happened? I am using a tomato box. Could this be a factor?

[billnorfolk]

Good morning and welcome to the lane.
What variety are your tomatoes , once grew some Russian blacks that had a purple tinge in the leaves ,are they indoor or outside and at what stage of growth .Often you will get a reddish colour under the leaves on some varieties and the leaves curl ,doesn't mean problems all the time ,Moneymaker at the final transplant stage often are red tinted under leaves ,makes them easy to distinguish from other varieties. A picture can tell a thousand words if you can get one on .

[lancashire lass]

as Bill says, a photo tells a lot. Purple leaves can also indicate being exposed to a cold condition (such as low temperatures at night)

I am using a tomato box.

maybe a photo would help as I don't know what a tomato box is