Those types of greens (similar to cabbage) are very starchy and not ideal tort foods. But, everything in moderation is ok. I just choose to only buy the "good" greens. If you already have some in the house (organic preferred), than sure, feed a little, but I sure wouldn't pick up a bunch of it just for your tort. Especially with one little tort, they will end up eating a lot of it in a short amount of time if you buy it just for them. Better off to try to grow your own greens & weeds, or buy spring mix (no spinach & chard) with 1-2 other heads of greens a week, rotating the types of greens (like turnip, mustard, collard, kale, watercress, endive, etc).