Ecological survey calendar › Habitats and plants
When to survey habitats and plants in Wales and England
Updated November 2026. Based on UKHab version 2.0 and current practice for biodiversity net gain and net benefit baselines.
Habitat surveys and condition assessments are best done from April to September, when most plants can be identified. Hedgerow surveys suit April and May, when woodland ground flora shows. Surveys outside the season are possible, but condition is then scored cautiously and a return visit may be needed.
Survey windows, sensitive periods and works timing
| Activity | Type | When | Notes |
|---|---|---|---|
| Habitat survey and condition assessment (UKHab) | Survey | Apr to Sep; Oct (not ideal) | April to September is the accepted window for condition assessment. Outside it, condition is scored cautiously and a return visit may be needed. |
| Hedgerow survey | Survey | Apr to Jul; Aug to Oct (not ideal) | Possible April to October, but April and May are best for woodland ground flora. |
| Detailed botanical survey (grassland, wetland) | Survey | late Apr (not ideal); May to Jul; Aug to Sep (not ideal) | Timed to the flowering of the plant community concerned. |
Optimal survey Possible, not ideal Sensitive period Works window
Timing depends on the site, the weather in a given year and what the planning authority and licensing body need. Upland and northern sites can run later. See every species group side by side on the ecological survey calendar.
About habitats and plants
Habitat surveys map and classify vegetation using UKHab and record its condition. That baseline drives biodiversity net gain in England and the net benefit for biodiversity case in Wales.
Legal protection
Habitats and species of principal importance are listed under section 7 of the Environment (Wales) Act 2016 and section 41 of the NERC Act 2006 in England. Rare plants are protected under Schedule 8 of the Wildlife and Countryside Act 1981. Important hedgerows are protected by the Hedgerows Regulations 1997.
Licensing
Wales: No licence is needed for survey. Removing a countryside hedgerow outside planning permission needs a hedgerow removal notice to the council.
England: No licence is needed for survey. Removing a countryside hedgerow outside planning permission needs a hedgerow removal notice to the council.
Practical tips
- Book habitat condition surveys in the growing season. A winter visit often means a return visit.
- Deciding whether a hedgerow is 'important' needs a spring visit to record woodland ground flora.
Common questions
When is the best time for a UKHab habitat survey?
April to September. Outside that window habitats can still be mapped, but condition is scored cautiously and a return visit in the growing season may be needed.
Can a biodiversity net gain or net benefit baseline be done in winter?
It can be started, but the habitat condition scores that drive biodiversity net gain in England and the net benefit case in Wales need the growing season. Plan for a spring or summer visit.
When should hedgerows be surveyed?
April to October is possible, but April and May are best for recording the woodland ground flora used to judge whether a hedgerow is important under the Hedgerows Regulations 1997.
Need a survey or advice on timing? Ecoleg's licensed ecologists programme surveys across Wales and England so the right work happens in the right season. Call 07356 123706.
Request a quoteSee the full calendarSources
- UKHab Ltd (2023) UK Habitat Classification, version 2.0.
- Defra (2007) Hedgerow Survey Handbook, 2nd edn.
- Common professional practice; confirm for each site.
Updated November 2026. General guidance only: confirm timing for your site with a suitably qualified ecologist.