This tree is spreading and vigorous, with a nice open habit that makes for an easy harvest. It is precocious and very productive; aggressive pruning is recommended to maintain tree vigor. Castleton is somewhat resistant to leaf spot and black knot, but it is susceptible to brown rot. This tree is partially self-fertile, but it will need to be partnered with another mid-season blooming European (Domestica) plum for full productivity. Potential pollenizers include Stanley, Jayfre, Italian, Longjohn, and Polly.

Ripening early, about three weeks before Stanley, this plum has a dramatic violet-blue skin and smooth, yellow-green flesh. The flavor is a good balance of sugar (16 °Brix) and acid, and the plum hangs well on the tree after ripening. Castleton cracks less than Stanley, is semifreestone, and it will store for about a month. This is an excellent plum for fresh eating or processing.

Castleton originated from a 1966 cross of Valor and Iroquois. It was released by Cornell in 1993.