I blanched and froze a sink full of assorted mustards last night, and your strain looks like a good one, with thin leaves and crisp ribs. Should be tasty stir-fried and drizzled with a sweet/sour dressing. The raw leaves work well in fruit-veggie smoothies, too. If you pick 3 leaves at a time per plant, you will get at least three harvests from fall mustard.

Somewhere around Christmas is when I plant mine.

Good luck, and it's a good thing you're working on it. This plant is a pain in you-know-what. One dang little plant can turn into hundreds. I'm not sure your method of inter-planting other plants will work. Garlic mustard is allelopathic and changes the soil chemistry. I can think of a lot more aggressive natives than Columbine and Va. bluebells however (try some Silphium). I'm working on a couple little patches of GM in the yard and sometimes pull the larger plants, but mostly use Roundup. Still I haven't been able to manage to eliminate every little plant. At least it hasn't spread.

Sorry for the delay, was away all weekend. Here is what I found for the rosette but it doesn't seem like much. Does this help you at all?