Most tree and hedge jobs have a season when they go better, cost less and cause the tree least harm. Two things then override the horticulture: wildlife law, which does not run on a calendar, and the council notice period, which does.
This checker works from today's date, so the answer is about now rather than in the abstract.
The nesting season is not a date range
People treat 1 March to 31 August as a ban. It is not. Under the Wildlife and Countryside Act 1981 it is an offence to damage or destroy a nest while it is being built or is in use — in March or in November. The March to August window is simply when nests are most likely.
In practice this means work is not forbidden in spring and summer; it must be checked first and stopped if a nest is found. Any competent firm inspects before starting and walks away from a hedge with an active nest in it. A firm that tells you nesting season is not a problem has told you something useful about the firm.
Bats are a year-round rule
All British bat species and their roosts are protected all year, whether or not a bat is present at the time. The trees to watch are mature ones with splits, woodpecker holes, lifting bark or hollow limbs. If a roost is suspected, work stops and a licensed ecologist is needed.
Questions
Can I cut a hedge in summer?
Only after checking it for active nests, and stopping if you find one. September and October are the straightforward months, once the season is over and before growth stops.
Why is winter cheaper for tree work?
Demand drops once the leaves are down, so firms have gaps in the diary. Deciduous trees are also dormant and easier to assess and dismantle without leaf cover, and frozen ground carries machinery better than wet ground.
Are there trees that should not be pruned in winter?
Yes. Cherry and plum should be pruned in summer to avoid silver leaf disease. Birch, maple and walnut bleed heavily if cut in late winter or spring, so they are better left until after midsummer.
How far ahead should I book?
Further than you think. Tree firms fill up from the first autumn gales, and a storm books them solid for weeks. If your window is November, get prices in September.
This tool is general information for homeowners in England, not legal advice. Rules differ in Scotland, Wales and Northern Ireland. Councils change their processes: always confirm with yours before work starts.