Plant European plum trees in full sun, in an area sheltered from cold winds and away from low-lying frost pockets. Soil should be neutral to slightly acidic, moist, and well drained. European plums are partially self-fertile. In other words they will produce some fruit on their own, but a larger crop will result if additional European plums are planted nearby. Japanese and European varieties will not pollinate each other. Plums should be allowed to ripen on the tree until fully coloured. Pick when the fruit is soft and comes off the tree easily. Unlike many other tree fruits. Do not prune plums in the winter. Rather, prune in early spring and then again thin them out in summer. Spray a lime sulphur-dormant oil spray in winter to kill over-wintering insects. A copper spray in summer can also be beneficial. Apply a fruit tree and berry fertilizer in early spring as growth begins.