Purple Viking can get to the 1 to 2 lb. range. I was probing the potting soil in the bucket today and found one good sized potato about an inch below the surface. I did not do any further probing nor did I uncover this one enough to determine just how big it is. It appeared to be at least 3 to 4 inches in length.Thanks for the info about MM vs. PV. Tin foil would be the better choice b/c it will occlude all light, as well as reflect heat off the pot. I found that my MM were a good size, at least quite a few of them were. About 4 - 6 oz.