This is my third year growing it.
Most of the plants died the first winter from
deer munching them. The second winter, I had a dog, so no deer. The plants did great until I got a young, completely untrained rescue dog in February who, as soon as the snow melted
enough to see the plants, basically did the same munching the deer had 🙄. I'm not sure what's different this year - timing, weather, initial health of plant - but rather than dying, the plants that were munched are all growing back from the base. My winters are colder than what they're supposed to be able to handle, but we have good snow cover, so a lot of them make it. I start new ones from seed every year, too.
I don't actually see a huge amount of variation in mine. They're pretty much all collard type leaves, with a bit of variation in the amount of raggedyness on the leaf edges. There's some colour variation, but nothing major. I've only had one plant so far that you could honestly say was something other than green. The most different plant I've grown so far is one that gets huge bunches of leaves growing from each leaf node. It actually gets hard to harvest from as the season goes on. Each harvest accelerates the growth at the nodes and it grows into a really dense bush. The leaves are huge and tender. It's my favourite plant, and I'm very happy to see it survived my dog's snacking. It produced a bit of seed last year, but not as much as the other plants that went to seed. The main variation I see is in size. There are some plants that just stay really small, which I don't want.
It's a good plant. Between it and Dietrich's wild broccoli raab, also from EFN, I've got the bulk of my greens covered. The raab leaves are so tender and sweet right now, even with the plants in full flower. They'll be good until the kale gets going again. Then the kale can take over until the snow covers the plants up.