I’m not sure what kind they are. I picked up sweet potatoes in the spring perported to be from a nearby farn. I figured if they were grown near my town, they should do well enough for me.

Sorry you’re struggling with clay. I’ve been growing mine in raised beds. I think I put in two parts compost, two parts peat moss, one part pearlite. I have one bed that was about a foot deep and it did ok. But the plants really seemed to love the two foot deep area. Second year growing sweet potatoes and first year giving them more depth.

What kind of amendments have you been adding? Are you noticing any progress towards better sweet potatoes?