Amit Enventres wrote:https://www.redwoodseeds.net/blogs/the-story-of-seed/14200361-brassica-basics-seed-saving-101
"What is going to seed in our garden now? We have Red Winter Kale (B. napus), Collards (B. oleraceae), Pak Choy(B. rapa) and Giant Red Mustard(B. juncea) all going to seed. They all have the same genus but different species so there will be no cross pollination. Easy!"
Joseph Lofthouse wrote:Some collaborators tell me they are saving mixed-heritage brassica seeds. They are selecting for highly edible leaves and flowers, and not worrying about specialized traits like kohlrabi shape, or cabbage heads. In other words, they end up with awesome tasting flowers, and often tasty leaves.
In my own garden, I haven't seen interspecies hybrids. I haven't seen hybrids between turnips and bok choi, because they flower at different times. Kale/cabbage hybrids are common for me. I reselect for kale types.
I don't grow a lot of brassicas, because of the aridity of my climate most springs. By the time the irrigation is active, it is too hot for them to taste good.