How to Prune blackthorn?
Little pruning is needed. Remove diseased, damaged, crowded or crossing shoots and unwanted growth. If silver leaf disease is a concern, prune in midsummer.

blackthorn · Prunus spinosa
Also known as: buckthorn; bullace; skeg; sloe; sloe plum; snag
Easy to grow native shrub or small tree, that can be used for hedging. Grows in any moist well-drained soil in full sun
Little pruning is needed. Remove diseased, damaged, crowded or crossing shoots and unwanted growth. If silver leaf disease is a concern, prune in midsummer.