Permission for a farm glasshouse or polytunnel block

Polytunnels are development. That has been the position since the High Court considered a commercial soft fruit operation in Hall Hunter Partnership v First Secretary of State, and it means a block of tunnels erected for a season on a field usually needs planning permission unless it fits within agricultural permitted development rights. Glasshouses are more obviously buildings and the same analysis applies, with the 1,000 square metre ground area limit in Part 6 deciding most cases before anything else does.

Whether polytunnels are development

The argument that a polytunnel is a temporary structure, moved around the farm and therefore not a building, rarely succeeds at commercial scale.

Courts and inspectors look at size, permanence and degree of physical attachment. Tunnels on driven steel hoops, in the same position for several seasons, with tracks and irrigation serving them, have the character of building operations however often the polythene is removed. A single small tunnel over a vegetable bed is a different matter.

There is a second route to development. Where the tunnels change the character of the land, for instance by covering a large proportion of a field permanently and introducing associated infrastructure, the use of the land may itself have changed materially. Applications are usually framed as operational development, but a case officer may raise the use point where the scheme includes reservoirs, packhouses or hardstanding.

Horticulture is agriculture for planning purposes under section 336 of the Town and Country Planning Act 1990, so the crop being grown does not take the operation outside agricultural policy. What it does not do is make the structures permitted.

Agricultural permitted development and its limits

Part 6 of Schedule 2 to the General Permitted Development Order 2015 gives rights on agricultural units, and the limits do most of the work.

Units between 0.4 and 5 hectares fall under Class B, which is narrower still and does not permit new buildings of this kind.

The 1,000 square metre limit is the one that catches horticultural schemes. A commercial tunnel block is frequently several hectares, and the calculation includes works carried out on the unit in the preceding two years within 90 metres, so incremental erection does not avoid it. Where the proposal exceeds any limit, the whole of it needs full planning permission rather than just the excess.

Prior approval is not permission, and it is not automatic. Where the authority determines that prior approval is required, siting, design and external appearance are all in play, which on a prominent site gives it considerable influence.

Scale, reflectivity and landscape effects

The landscape objection is about the surface, not the structure.

A hectare of polythene reads as a light grey or white plane in the landscape, visible from far further than a barn of the same footprint, and glasshouse glazing adds reflectivity that changes through the day. In a National Landscape or on rising ground the effect can be the determining issue.

Mitigation that works is mostly about position and colour. Following the contour rather than cutting across it, breaking blocks with retained hedgerows, setting back from ridgelines, and using darker structural elements all help. Planting a new hedge does not screen a two metre structure for several years, so say what the effect is in year one rather than in year fifteen.

Where the setting is sensitive, a landscape and visual impact assessment prepared to the GLVIA3 approach is the proportionate document. On an unremarkable site an appraisal with annotated viewpoints may be enough, and it is worth asking the officer which they want at pre-application.

Artificial lighting is a separate question. Supplementary lighting in glasshouses produces sky glow that carries for miles in a dark rural area, and a lighting assessment against the Institution of Lighting Professionals guidance, with blackout screens secured by condition, is normally expected.

Drainage and surface water run-off

Tunnels and glasshouses are impermeable. A field that absorbed rainfall now sheds it from thousands of square metres of polythene into the gaps between the tunnels, and that is where the complaint from downstream neighbours comes from.

Deal with it properly. Run-off should be collected, attenuated and either infiltrated or discharged at a rate no greater than the greenfield rate for the site, with the calculation shown. Many growers want the water anyway for irrigation, so storage reservoirs frequently solve the drainage problem and the supply problem together.

The drainage strategy should cover the tunnel block, the tracks, any hardstanding and the reservoir, and should address soil erosion in the alleyways, which is a genuine issue on sloping sites.

Best and most versatile land and workers

National policy expects the economic and other benefits of the best and most versatile agricultural land to be taken into account, meaning grades 1, 2 and 3a.

There is an obvious tension. Horticulture uses good land because good land grows good crops, and the policy is directed at preventing the loss of that land to development. Where the tunnels are demountable and the soil remains in cultivation, the loss argument is weak and should be answered directly with an agricultural land classification survey where grade is disputed. Where the scheme involves permanent hardstanding, packhouses and roads, the loss is real and should be quantified.

Seasonal worker accommodation is the question growers least want on the application and officers most often ask about. A tunnel block of any scale needs pickers, and caravans appearing on the holding afterwards generate enforcement complaints. Applying for the accommodation at the same time, with a temporary or personal permission tied to the horticultural operation, is usually better than dealing with it later.

An illustrative example

A 40 hectare holding proposes 6 hectares of Spanish tunnels for soft fruit on gently sloping land outside a National Landscape boundary. Part 6 does not help, since the ground area far exceeds 1,000 square metres. The application includes a landscape assessment with winter and summer viewpoints, a drainage strategy attenuating to greenfield run-off rate into a new irrigation reservoir, and a separate application for 24 caravan pitches for seasonal workers. This example is illustrative.

Access and vehicle movements

The daily traffic is modest for most of the year and heavy during picking, with chilled vehicles collecting daily and worker minibuses at shift changes.

Describe the peak. Give the number of HGV movements a day in the harvest period, the vehicle type, and the route to the nearest classified road. Visibility splays at the field access will be measured against the actual speed of traffic, not the posted limit, so commission speed surveys where the access is on a rural road with long sight lines.

Internal circulation matters more than people expect. A vehicle reversing out of a field gate onto a 60 mile per hour road is a refusal reason in itself, so show the turning area on the plan.

How applications are usually decided

Most horticultural structure applications turn on landscape effect, drainage and the treatment of workers, in that order. Policy support for agricultural development and for food production is generally there in the development plan, and the officer is looking for reasons to manage the impacts rather than reasons to refuse the principle.

Temporary permissions are common on first applications, with a five year term allowing the effects to be assessed. That is a reasonable outcome to accept, though it complicates investment decisions, so it is worth discussing at pre-application rather than receiving it as a surprise.

A planning statement that sets out the agricultural justification, the seasonality, the landscape response and the drainage approach will do most of the work.

Enter your postcode on PlanScope to see which reports a horticultural scheme is likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.