Oh my! You have a RED Zebra (LOL).

Did you buy plants or start them from seed?

If you started them from your own saved seed, perhaps they crossed with a red tomato last year.

Linda

If you leave GZs on the vine for a long time, time turn from green to yellow to a bronzy red. I actually prefer them this way.
There is also a tomato that looks just like the green Zebra but is red with stripes. I have forgotten its' name.

I've grown Green Zebra several times and have never seen one turn a bronzy red where I grow tomatoes. But then I don't really like the taste and Tom Wagner who bred it, knows that. LOL

GZ does cross easily with other varieties and both Red Zebra and Black Zebra are known, both stable.

I once trialed an Orange Zebra that Tom bred and sent seeds to me that were included with 21 other varieties, and it was a disaster, splits all over the place, and he abandoned that one.

Carolyn

The bottom of the tomato turns a yellowy orange at most, never red. This is the first year in a while that I haven't grown any green or red zebra tomatoes. I only ever grew them for the novelty factor; they looked good in salads but I didn't really enjoy the taste.

For sure GZ should not be turning red. Yellow at most and it's better when it still has that tart taste. Unless you have Red Zebra or tigerella or mr.stripey?

Here is the picture of the GZ tomatoes. 1 that turned red and the other that's still green.

I have a Cherokee purple planted right next to the GZ and some other standard red varieties about 20 feet away.

Was this plant just mismarked when I bought it? Or cross pollination effects?

That doesn't look stripey at all to me. I would say that somebody switched tags and you have an unknown red tomato. It looks good though. I hope it's tasty!

Linda

Switched tags as Linda said. Someone picks up a tag, looks at it, then sticks it back into a random pot. Or it's possible, but less likely, that it was just mislabeled to begin with.

Rodney

Agree with the two former posts.. Def not a GZ

Agree . It is a case of switched tag. It is not Zebra of any kind.
Enjoy whatever it is !

And Green Zebra is not an heirloom as the tag indicated,

Carolyn

You are right. But it was sold as "Heirloom " in the supermarket . I bought the tomato, saved seeds an planted.
Now what ?