The most widely planted European plum in the East, Midwest, and South, this tree has large, dark blue fruit with firm, richly flavoured yellow flesh. It bears heavily every year, and is self-pollinating. Fruit ripens after mid-August, into September in northern regions. (This is a plum. It is called Stanley Prune because it is best used to make prunes)
Do not try to cross pollinate a European plum with a jap plum.
Stanley plum is self-pollinating