Hedge trimming and topping – Established hedges require trimming to keep them dense and compact. Formal hedges require more frequent trimming than informal hedges. New hedges require formative pruning for their first couple of years after planting. Formative pruning is usually carried out in winter or spring. After this, maintenance trimming is carried out, usually once a year for informal hedges and twice a year for formal hedges. Some formal hedges may need three cuts a year. Maintenance trimming is generally carried out between spring and summer.