Not sure if this is your first time planting sweet potatoes but in case your soil and temps are anything like ours (heavy clay, zone 7): they LOVE the clay, and we can't plant them until May because they dislike the cold (not just freezing temps - I think they actually don't like anything below 50 or so).

Sweet potatoes are awesome for covering bare soil here. So good that last year I thought I'd use them for ground cover as I got a few perennial flowers started, and the poor flowers never had a chance - it was sweet potato greens everywhere, almost immediately. They grow fast and vigorously. I believe they're edible if you're into greens, and in any case both goats and rabbits love them.

Your slips look wonderfu!