Sclerocactus parviflorus is the most widespread of the genus and probably the easiest in culture. This species occurs in Arizona Strip area, around Arizona-Utah border and into Four Corners area. Plants are somewhat hard to find but not too rare.
This plant in picture is growing on a spectacular setting with red sands as a background. Plants are variable in spines and flower color, some are blond or pure black-spinned and there are locations where white flowering plants are present.
Growing from seed makes no problem for the first two years when plants are gaining size pretty quickly, rlike some of Ferocacti. For the second summer seedlings likely would prefer to have summer dry period from end of May to August, simulating Arizona summer drought. August is a time for monsoons and careful watering is again welcomed. I hope looking at that picture below will not inspire you into mixing any humus earth components for these plants roots.