Trimming native hedgerow
I planted a native hedgerow back in February. Then it was just sticks and is doing quite well. It comprises of Hawthorn, Hornbeam, Field Maple, Hazel and Dog Rose. The Hawthorn in particular has grown quite tall.
When and how much do I need to trim so it comes back thicker next season? Will grass growing at base of the hedgerow cause any harm?