It's one of my favorite Sedges. I have at least 2 dozen clumps of it in my garden, all grown from seed. It's both a stand-alone specimen and a massed plant. The flower/seed heads are easily the most unique of any grass, providing interest from late spring all the way through winter. I cut dozens of the seed head stems each winter for use in dry arrangements, and use them with fresh-cut flower arrangements in summer.

Gray's Sedge is hardy to zone 2 and likes a moist environment, although it is drought tolerant when established. Given adequate water, it will thrive. It can be grown in full sun to quite a bit of shade. The foliage is darker green in shade than sun, but remains a bright spot in the garden.

A clump of C. grayi will reach 2' in height, and gradually expand in diameter, although not quickly. It self-seeds very lightly in my garden, and I help it along where I have it massed, by crumbling the dry seed heads at it's own feet. I don't think there is any way to classify it as invasive, particularly in your zone.

After very mild winters, I don't have to do anything to it except for pulling out a few dead blades and any flower stems still present. In your zone, you'll probably have to cut it almost to the ground each year, in late winter. Do it early, as it is a cool-season grass, and starts re-growth very early in Spring.

Thanks Donn for taking the time and giving me such a thoughtful answer. It's helped a lot, and I am now reassured that c grayii is a good plant and worth growing.