In the intermountain west, in and close to the Great Basin, they are invasive. I finished taking them out last November. The grew all-right, suckered, spread and are impossible to pick. Why did I plant them in the first place? An out-of-print book by Peter Robertson, Pheasants, "as far as shrubs go, Seabuckthorn (Seaberry) are the best for pheasants" (rough quote). If you are in the intermountain west, don't plant them!