Monty Don has advised gardeners that October is the ideal time to trim hedges, as the nesting season for robins and other garden birds has ended.
Safe to trim after nesting season
In a 2024 blog post, Monty clarified that hedge cutting is now completely safe to undertake, since "the vast majority of nesting birds have fledged" in the shift between summer and autumn. Gardeners needn't worry about disrupting active nests, which is strictly prohibited during the official bird nesting season from March to August.
Cutting at the close of summer can also anticipate "results in slower, less vigorous regrowth than a winter trim," meaning the shape you trim into now is more likely to last through the colder months instead of fresh unwanted growth from cuts later in the year.
Check for late nesters and trim correctly
Cutting too soon, such as in the peak of summer, can cause issues, with plants more prone to heat stress compared to those trimmed in the cooler days of late September and early October. Before beginning, Monty emphasises it's vital to thoroughly check inside the thicker parts of the hedge for any late nesters that might remain.
For the best results, Monty recommends beginning with the sides of the hedge to create a gentle "batter," or outward slope running from top to bottom. This helps prevent the lower portion from being overshadowed by fuller growth at the top, ensuring sunlight is distributed more uniformly for a thicker plant throughout, or as Monty puts it, "fully 'furnished' right down to the ground."
Finish with clippings disposal
Once the sides are complete, turn attention to the top, where a piece of string stretched between two canes serves as a straightforward guide for a level cut. Restraint is key, as gentle shaping and general tidying should be the aim for this month, with more severe pruning reserved for next year to avoid tender new growth vulnerable to frost damage.
Once finished, Monty points out it's worthwhile mowing up the resulting clippings and adding them directly to the compost heap, while evergreen trimmings should be taken to local councils' green waste facilities.
