Sun on ground for allotments and community growing space

Allotments and community growing plots need more sunlight than a domestic garden, and the standard planning tests were not written with them in mind. If a proposed building will overshadow a growing site, the objection that carries weight is the one that measures the loss across the growing season rather than complaining about a single afternoon in December. Allotment overshadowing from development is assessable, and the assessment is not difficult, but it has to be framed properly to be treated as a material consideration.

Start from what the plot is for. A lawn tolerates shade. Runner beans, tomatoes and brassicas do not, and a plot that drops below roughly half a day of direct sun through the summer stops being productive in a way that a shaded garden does not stop being a garden.

Why growing land is different from amenity land

The BRE guidance on site layout planning for daylight and sunlight, third edition 2022, contains a sun on ground test for amenity areas. It asks whether at least half of the area receives at least two hours of direct sunlight on 21 March, the spring equinox, in the proposed condition. That single date is a screening test designed for gardens, courtyards and play areas.

For growing space, two hours at the equinox is a floor rather than a target. Seed sowing, hardening off and early cropping all happen in March and April, and the plants that produce the bulk of an allotment's yield are in the ground from May to September. A test that passes on 21 March can still describe a site that loses its afternoon sun for the whole of July.

That is the gap an objection should work in. Nothing stops an applicant's consultant running the same calculation on additional dates. The output is a shadow plot for each date and time, and the comparison between existing and proposed conditions is the evidence a committee can weigh.

The dates and times worth asking for

A useful request to a local planning authority is that the applicant's Overshadowing Study covers the growing season rather than a single equinox snapshot. In practice that means hourly shadow plots on three or four dates.

1. 21 March, the standard BRE reference date, for comparability with other schemes.
2. A date in mid-May, when transplants go out and shade slows establishment.
3. 21 June, the summer solstice, which shows the best case the site will ever see.
4. A date in September, when late cropping and seed saving depend on warmth.

Ask for existing and proposed shadows on the same sheet at the same scale, with plot boundaries drawn on. A study that shows only the proposed condition tells you nothing about the change, which is the point covered in mirror image baselines and existing obstructions.

Hourly plots from 9am to 5pm are the usual convention. Anything coarser hides the pattern.

Measuring the proportion of plot area affected

The number that persuades is the percentage of cultivated area losing direct sun, plot by plot, not site-wide. Averaging across a whole allotment field conceals the fact that the three plots along the northern boundary lose everything while the rest are untouched.

A site association can do this work itself with a measured plan and the applicant's shadow plots. Overlay the shadow outline for each hour onto the plot layout, measure the shaded area, and tabulate it. The result is a table of plot numbers against hours of direct sun retained, which is far harder for an officer to set aside than a sentence about loss of light.

Illustrative example: on a site of 40 plots where the proposed block sits on the southern boundary, five plots might retain fewer than two hours of direct sun on 21 March and eight might lose all afternoon sun in June. Those are the plots the objection is about. The figures here are illustrative only and every site has to be measured on its own layout.

Where the applicant has commissioned a Daylight and Sunlight Assessment for neighbouring housing, ask whether the same model can output the growing land results. The model already exists. Extending it is a matter of hours, not weeks.

Statutory allotment status and what it protects

Allotment land held by a local authority for the purpose of allotments is statutory allotment land, and disposal or appropriation to another use requires the consent of the Secretary of State under section 8 of the Allotments Act 1925. That protection attaches to the land itself, not to the sunlight falling on it, so it does not prevent a neighbouring development. What it does is establish that the land has a protected long-term function, which bears on how much weight loss of productivity should carry.

Temporary allotments, privately owned community gardens and land let on short leases do not have that protection. They may still be protected by a local plan open space designation or a Local Green Space allocation, so check the policies map before assuming otherwise.

The National Planning Policy Framework, current edition published 17 August 2026, contains open space and community facility policies that resist the loss of valued open space unless it is surplus or replaced. Loss of productive capacity through shading is not loss of the land, so the argument is usually about harm to an existing community use rather than about the open space policy directly. Say so plainly rather than overclaiming, because an officer who spots an overstated policy point discounts the rest of the objection with it.

Evidence a site association can assemble

Councils give more weight to written records than to recollection. Before the consultation period closes, gather:

• A measured plan of the site with plot numbers, showing which plots are cultivated and which are fallow.
• The tenancy agreement or lease, and any council decision that created the site, to establish status and tenure.
• Cropping records or a simple survey of what each plot grows, which demonstrates the site is productive rather than ornamental.
• Photographs taken at the same times of day across the season, with dates, showing existing sun patterns.
• Any constitution, waiting list or membership record showing active community use.

Waiting lists are useful. They answer the argument that the site is underused without requiring anyone to make a claim about demand that cannot be checked.

Mitigation and replacement that actually helps

Objecting is stronger when it comes with an alternative. Shading is a function of building height, position and the gap to the boundary, so the changes that work are the ones that alter massing on the southern edge: stepping the block down, pulling it back, angling the footprint, or moving height to the northern end of the site. Obstruction angles and the early massing test is the quickest way to show that a modest reduction recovers most of the lost sun.

Replacement provision is the weaker remedy and should be treated as such. New plots on a shaded corner of the same site are not equivalent. If replacement is offered, ask for the sun on ground calculation for the replacement land before it is accepted, along with soil depth, water supply and a management arrangement of at least the same length as the tenure being lost.

Conditions can secure the outcome where the principle is accepted. A condition requiring the approved massing to be built as modelled, and one requiring a landscape management plan for any replacement growing land, are both enforceable.

Putting the objection in front of the right people

Submit the objection in writing during the consultation period, addressed to the case officer, with the shadow analysis as an attachment rather than a description in the text. Ask the parish or town council to comment separately if there is one. Request that the application goes to committee if the site is a designated open space, and ask to speak.

Officers read a lot of objections that assert harm. Very few arrive with a plot-by-plot table and a set of hourly shadow plots. Presenting results in a form a committee can absorb in two minutes is a skill in itself, and presenting daylight results a committee can read covers the formats that work.

And keep the ask specific. A request to refuse is easy to set aside. A request to reduce the southern block by one storey, supported by a calculation showing what that recovers, is a proposition the case officer can put to the applicant.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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