I LOVE the scent of Sweet Vernal Grass!
I don't know the answer to your question, but a couple of years ago when I let the lawn grass grow out and flower/set seed to differentiate their species, I discovered to my delight a clump of Sweet Vernal Grass in the middle of the back yard. I moved it to an area I designated as Sunny Meadow Garden, and have been letting it grow there. It's doesn't spread much at all, being clump forming, so I let it go to seed. This spring, I discovered a tiny new clump in the SMG after it sent up a flower stalk, so I marked that off and am letting it grow as well.