Several years ago in my novice ignorance I put in several plums hoping/experimenting that the listed chill hours for them was incorrect. So far no fruit yet on Coe's Golden Drop (I recently grafted Improved French and Pearl on it), Geneva Mirabelle (I recently grafted several other mirabelles onto it), Green Gage (with recent grafts of other gages). I did get one or two fruits from Cherry Plum Delight (I do not have Sprite, the recommended pollinator but I grafted Elephant Heart, Laroda, Inca, Sierra, Catalina, Shiro, Kelsey and Golden Nectar onto it). I do get fruit on Weeping Santa Rosa (beautiful little tree), and Burgundy (recent grafts of Beauty on that one). It's perhaps still too soon to give up hope but I may dig them up and move them to Central CA where they'll certainly get the chill they need.