From Yes-in-Principle to Dug In: Building a Raised Bed on a Shared Back Green

Once your neighbours have said yes, building a raised bed on a shared back green comes down to four decisions: get the agreement and the bed's footprint in writing, build the bed to drain by itself because there is no soil beneath it, choose a modular bed that can be lifted and moved, and buy the fill in one bulk order split between households. Pick the spot for sun, wind, bins, washing lines and where the water will run, not just for where there is space.

Still working out whether the factor or your co-owners will agree, weight limits on a suspended deck, no outdoor tap, or getting bulky materials up a common stair? The guide to tenement, flat and balcony growing in Scotland covers that groundwork. The rest here assumes the answer is yes.

Turning "yes, in principle" into something written down

Tenement back-green projects range from informal neighbour consensus to formal fee-based associations, depending on how many households are involved and how much money changes hands. Whichever it is, convert the verbal yes into something more durable before any digging or drilling. Two things are worth pinning down, even informally:

• A defined, bounded area, not a claim on the whole green. "The bed goes in the corner by the wall, roughly 1.5m by 1m" is a very different proposition to co-owners than "we're doing some gardening out back", and much easier to say yes to.
• Something in writing, even an email or a note on the stair noticeboard, recording who agreed, what was agreed and roughly what it covers. This isn't about legal enforceability. Verbal understandings get remembered differently a year later, especially once a flat changes hands and the new owner wasn't part of the original conversation.

Check who owns the ground. Back greens are typically designated common "scheme property" in tenement titles, with all owners sharing responsibility. Only where the title deeds are silent does the Tenements (Scotland) Act 2004 default rule apply, giving an outdoor area to the owner of the bottom flat nearest and adjacent to it. Your own titles decide, and if the position is unclear, a solicitor can tell you. The Act's Tenement Management Scheme lets owners make binding majority decisions (one vote per flat) on maintenance, including gardening, but it doesn't clearly cover putting a new structure on common ground. So for a raised bed, aim for agreement from every owner rather than relying on a vote, and keep the bed small and reversible so nobody has much to object to.

Where the block sits in a conservation area or is itself a listed building, which applies to many tenement areas in Edinburgh and other Scottish towns, check with the local council whether a shared-ground structure needs separate sign-off. A factor's or neighbours' agreement covers the neighbours, not planning or listed-building consent.

Reading the ground before you build

Many tenement back greens weren't built as gardens. They are paved, cobbled or hard-packed yards, typically draining to a gully or channel feeding a shared drain rather than to open soil beneath. That changes how you need to build a raised bed compared with one on open soil.

Check how much sun the spot gets and how exposed it is. A green enclosed by the tenement on several sides can be shaded for much of the day, and the same enclosure can channel wind into a gusty corridor. Watch the spot for a few days before committing. A shaded, wind-funnelled corner suits shade-tolerant, wind-hardy crops such as currants, rhubarb, chard and hardy herbs better than anything wanting full sun. Plan for slugs from the outset, since a damp, shaded, enclosed back green is the sort of sheltered, moist spot they favour, and in coastal or city-centre closes for gulls investigating freshly turned soil or uncovered compost.

In a soil garden a raised bed's base relies on the ground underneath to soak away excess water. On a back green there is usually no "underneath" to soak into, so the bed has to do all the drainage work. For a timber bed, drillA shallow, straight groove made in prepared soil for sowing seed into, at a set depth so germination and rows are even. Full definition → plenty of holes in the sides. For a masonry bed, leave gaps at about 45cm intervals between the joints in the first two courses. Cover the openings on the inside with fine wire mesh and heap gravel against the mesh when filling, so soil doesn't wash out with the water. For a bed on a hard surface, use a fill mix with more sharp sand (coarse, gritty horticultural sand, not soft play sand): three parts organic matter, four parts sharp sand and seven parts topsoil.

Depth: allow about 30cm for dwarf bulbs, salad leaves and strawberries and 45cm or more for fruit bushes and shrubs (RHS). On a hard surface there is no soil below for roots to reach, so lean toward the deeper end for anything with a bigger root run. Keep the width under about 1.5m so you can reach the middle without standing in the bed.

Placement matters as much as the drainage build. Walk the green and check the spot against:

• Access routes: the path to bin stores, the stair door, any fire escape and the route factors or contractors need for common repairs.
• The drying green: washing lines and drying poles are heavily used on most back greens, and a bed that blocks or shades a line will cause more friction than almost anything else you could build.
• Drainage gullies: never sit a bed over or immediately upstream of one. You want water finding its way to the drain, not pooling against a gully cover the bed is partly blocking.
• Bin stores: a soil-filled bed hard against a bin store gives rats and mice cover and a food source close together, so leave a clear gap of paving between the two.

Choosing a bed that fits shared, changeable ground

Because a shared-ground arrangement can be renegotiated, restricted or ended by people other than you, favour a modular or moveable bed over a permanent build. A structure that boltsA plant switching early into flowering and seed production, usually triggered by stress, after which leaves, roots or bulbs turn bitter or unusable. Full page → together, sits freestanding on the surface or can be lifted and relocated in an afternoon is a much lower-risk commitment than something concreted or fixed in place. If the agreement changes, you take the bed with you rather than negotiating its removal.

Whatever the material, timber, metal or stone (raised bed materials compared goes through the trade-offs), two things matter more on shared, hard-standing ground than in a private garden:

• Weight distribution. A filled raised bed is heavy: a 1.5m by 1m bed at reasonable depth easily holds several hundred kilograms of damp soil once planted and watered. On old paving or cobbles, especially near a coal cellar, drain cover or any suspended structure below the surface, that weight is concentrated on a few point loads rather than spread evenly.
• Boundary and access clearance. Position the bed so no part of it, including any lip, handle or corner bracket, overhangs a boundary line, a shared access path or a neighbour's step. A bed that is within the agreed footprint but intrudes on someone's route to their own door will undo the goodwill the agreement was built on.

Filling it: ordering for a household-shared bed

Soil and compost for a raised bed are sold either in small pre-bagged units or in bulk as a "tonne bag" or loose by the cubic metre from a builders' merchant or garden centre. For a bed of any real size, buying in bulk and splitting the cost across the households using it is usually far more efficient than everyone buying small bags.

For a bed shared by three or four flats, a single bulk order split by household, either by number of flats or by rough share of bed space, usually works out cheaper per household and simpler to organise than everyone turning up with their own trolley of bags. It also means only one delivery needs coordinating with the factor or the neighbours downstairs. Prices vary a lot by supplier, material and postcode, so get an actual delivered quote before agreeing how to split it, rather than estimating from bagged prices at the garden centre. Getting the bags up a common stair with no rear vehicle access is a separate problem, covered in the tenement growing guide linked above.

Where the water goes

A bed on a back green will drain, but the run-off has to land somewhere, and on shared paved ground that is rarely neutral. Water draining from a bed on hard standing runs across the paving to the nearest low point, which is often the route used by other households' washing lines, bin stores or a ground-floor window. Before finalising the spot, check what sits downhill:

• Is a neighbour's washing line, or the drying pole itself, in the path the run-off would take, especially after heavy rain when the soil drains fastest?
• Does the run-off route pass a bin store, where standing water encourages mess?
• Is there a basement or ground-floor window, air brick or light well near the low point the water is heading toward?

This is rarely a major engineering problem. It means angling the bed so its natural drainage points toward the green's own drainage gully rather than across a path other households use, and checking after the first heavy rain that it behaves as expected. Water is the other thing to plan: many back greens have no outdoor tap, so decide in advance where it will come from. And mention where the run-off will go when you first raise the project with the factor; a plan that has already thought about the water leaves one less thing for them to ask about later.

If the arrangement ever needs to be undone

Agreements over shared ground are not permanent by nature. A household moves and the flat is sold to someone who wasn't part of the original conversation. A factor changes practice. A co-owner who wasn't consulted, or has changed their mind, objects. These are the ordinary ways shared-property arrangements shift, and the written note from the start is what you point back to when a new owner asks why there's a raised bed on ground they now part-own. If the bed has to come down, its soil can usually be bagged and reused elsewhere, or offered to a neighbour or a nearby community garden rather than binned.

One question to raise before you build: who is responsible if someone trips on the bed's edge or a corner bracket on common ground? Ask the factor, or check against your own home contents insurance, while it is still hypothetical. Whatever the answer, a bed you can lift, reduce or remove in an afternoon beats one set in concrete.

Common questions

Sources