Hedgerows provide important habitat and food resources for overwintering birds, mammals and invertebrates. Currently, 41% of managed hedgerow length in England forms part of three Agri-Environment Scheme (AES) options, which specify a reduction in hedgerow cutting frequency from the most common practice of annual cutting. These AES options aim to increase the availability of flowers and berries for wildlife, but there has been little rigorous testing of their efficacy or estimates of the magnitude of their effects. We conducted a factorial experiment on hawthorn hedges to test the effects of (i) cutting frequency (every 1, 2 or 3 years) and (ii) timing of cutting (autumn vs. winter) on the abundance of flowers and berry resources. Results from 5 years show that hedgerow cutting reduced the number of flowers by up to 75% and the biomass of berries available over winter by up to 83% compared to monitored uncut hedges. Reducing cutting frequency from every year to every 3 years resulted in 2.1 times more flowers and a 3.4 times greater berry mass over 5 years. Cutting every 2 years had an intermediate effect on flower and berry abundance, but the increase in biomass of berries depended on cutting in winter rather than autumn. The most popular AES option is cutting every 2 years (32% of English managed hedgerow length). If these hedges were managed under a 3 year cutting regime instead, we estimate that biomass of berries would increase by about 40%, resulting in a substantial benefit for wildlife.