Goerwitz

Although nonnative, Korean bush cherries are hardy in USDA zone 4 (where I live), and not particularly invasive. The cherries are small, sour, and really tasty. Just after the point when they become ripe enough to be really good to eat, birds swoop in and strip them clean. I mean, in a single day you go from thousands of cherries per bush to maybe a half dozen. If you want them around for a while, invest in some bird netting—or pick them quickly as soon as they're ripe.