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Getting the siting decision right is one of the most underrated parts of buying a greenhouse. The best greenhouse in the world, positioned in the wrong place or built on an inadequate base, will underperform for its entire service life. A well-positioned greenhouse on a properly prepared base, by contrast, requires almost no ongoing structural attention and provides a growing environment that improves with every season.
This guide covers the three decisions that determine where and how your greenhouse goes: where to position it in your garden, whether you need planning permission, and what base preparation your specific model actually requires. The last of these is more straightforward than many buyers expect — particularly for the KLASIKA and BALTIC LT range, where the arch-driven ground-anchoring system means that most models require no poured concrete and no traditional foundation at all.
In the UK, the single most productive greenhouse orientation is with the longest wall facing south. This maximises the total solar energy the greenhouse receives across the year, and particularly in spring and autumn when the sun is lower in the sky and the angle of incidence from the south is most beneficial.
For a tunnel or arched greenhouse — which is the shape of the majority of the KLASIKA and BALTIC LT range — this means positioning the greenhouse so the ridge runs east to west and the long sides face south and north. The south-facing wall receives direct sunlight through most of the day; the north-facing wall benefits from reflected and diffused light.
For a house-shaped greenhouse — the KLASIKA HOUSE or KLASIKA BERNARD — the same orientation applies. With the ridge running east to west, both of the longer south-facing panels receive maximum light from the front and the pitched roof catches direct sun throughout the day.
If south-facing is not possible: East-facing is the second-best option. An east-facing greenhouse receives morning sun — the most efficient sunlight for plant photosynthesis, which is most active in the cooler morning hours — and is shaded in the afternoon. West-facing is workable: afternoon sun is sufficient for most crops, though the greenhouse will be cold and slow to warm in the mornings. North-facing is the orientation of last resort — usable but noticeably less productive, and more dependent on supplemental heating to compensate for reduced solar gain.
In practice: The difference between a south-facing and a west-facing greenhouse matters most at the seasonal extremes — early spring and late autumn — when the available growing window is being stretched and every degree of solar-gained warmth counts. At the height of summer, a greenhouse in any orientation receives more than enough light and heat. Position for the shoulder seasons and the summer will look after itself.
Shade is the enemy of productive greenhouse growing. Even partial shade — from a nearby tree, a fence, a garden building, or the house itself — reduces growing capacity significantly. The crops that make a greenhouse most worthwhile — tomatoes, cucumbers, peppers, aubergines — are high-light-demand plants. Give them shade and they produce less, grow slower, and are more susceptible to disease.
The practical rule: The greenhouse should receive at least five to six hours of direct sunlight daily during the main growing season — mid-March to mid-October. Less than this and the growing environment is compromised for the crops that benefit most from a greenhouse.
Trees: Deciduous trees are manageable — they shade in summer when light is least limiting and are bare in winter and spring when maximising light is most important. Evergreen trees are more problematic: they shade year-round, and the leaf and needle drop onto polycarbonate panels is a cleaning burden as well as a light reduction. Position the greenhouse at least its own height clear of any significant evergreen tree to the south.
Fences and buildings: A fence or building directly to the south of the greenhouse will cast a significant shadow in the lower-sun months when the shadow is longest. The practical guide: the greenhouse should be at least 1.5 times the height of any south-facing obstacle clear of that obstacle to avoid meaningful shadow from it at the critical growing times of year.
Internal shading: The greenhouse’s own frame creates some internal shade — the omega-profile arches cast small shadows as the sun moves across them during the day. This is normal and inconsequential for growing performance. The closely-spaced arches of the KLASIKA ARCHED and KLASIKA HOUSE at 50–67cm create slightly more shadow at any given moment than the wider-spaced arches of the BALTIC LT at 100cm, but neither is significant enough to affect growing outcomes.
There is no structural requirement for a greenhouse to be close to the house — but for the convenience of daily use, closer is almost always better.
A greenhouse you have to walk forty metres to reach in cold, wet weather is a greenhouse you will visit less often, water less reliably, and manage less attentively than one accessible from the back door in a few steps. Greenhouse crops — particularly tomatoes and cucumbers at the height of the season — need daily attention. Easy access to the house also means easier running of electricity if you use a heater, propagation lighting, or thermostatic temperature control.
The practical recommendation: position the greenhouse as close to the house as the siting criteria allow, while respecting the clearance and access requirements below.
Whatever the model, the greenhouse needs sufficient clearance around it to assemble it, maintain it, clean the panels, and open the doors without obstruction. The minimum clearances worth observing:
Long sides: 50cm minimum between the greenhouse side and any fence, wall, or other structure. This is the minimum for panel cleaning access and is not comfortable as a working space. 80cm–1m is preferable — enough to move along the side with a watering can or cleaning equipment without turning sideways.
Door ends: 1m minimum clear in front of any door. This allows the door to open fully, enables you to enter carrying equipment, and provides the space to work at the open end in good light. If you plan to add a rear door — available as an accessory for all KLASIKA models — allow 1m at each end.
Overhead clearance: Polycarbonate greenhouses do not require overhead clearance in the way that tall structures do, but overhanging branches should be clear of the roof surface. A branch resting on the roof adds load, deposits debris into panel channels, and may damage panels in strong wind. Keep the overhead clear to at least 30cm above the ridge.
Wind is the environmental factor that most buyers underestimate. A greenhouse that is well-positioned for light and access but exposed to regular strong winds will suffer: panels shift in their channels, heat escapes faster, and in extreme weather the structure can be placed under significant stress.
Shelter without shade: The ideal is a greenhouse that is sheltered from the prevailing wind (south-westerly in most of the UK) by a hedge, fence, or building to that direction — but without being shaded to the south. A low hedge to the west provides windbreak effect without material shade impact. A solid wall to the south provides excellent shelter but at an unacceptable cost in shading.
Open and exposed sites: For genuinely exposed positions — hillside gardens, coastal locations, open field edges — additional ground anchoring of the greenhouse is strongly recommended regardless of model. All KLASIKA and BALTIC LT arches drive 35cm into the ground as standard anchoring; additional ground anchor bolts at the base of the frame at regular intervals significantly increase resistance to wind racking and uplift. In very exposed positions, the closely-spaced arch models (KLASIKA ARCHED, KLASIKA HOUSE at 50–67cm arch spacing) are preferable to wider-spaced models for their greater structural rigidity.
For the vast majority of UK gardeners, installing a greenhouse does not require planning permission. Under England’s Permitted Development rights, a greenhouse that meets the criteria set out below is a permitted development — meaning it can be built without application to the local planning authority.
The criteria are straightforward:
Position: The greenhouse must not be positioned forward of the principal elevation of the house (i.e., in the front garden visible from the street, or in front of the main front wall of the house).
Height: If the greenhouse is within 2 metres of the property boundary, the maximum ridge height is 2.5 metres. If it is further than 2 metres from the boundary, the maximum ridge height for a dual-pitched (gabled or arched) roof is 4 metres.
Coverage: The total area covered by outbuildings, sheds, greenhouses, and similar structures must not exceed 50% of the total garden area excluding the house footprint.
KLASIKA and BALTIC LT models within these limits: All standard models in the range have ridge heights between 2.10m (BALTIC LT, KLASIKA SLIM, KLASIKA EASY) and 2.45m (STANDART KLASIKA). Every model is within the 2.5m boundary limit, meaning all can be positioned within 2 metres of a boundary under Permitted Development without any planning application. The 50% coverage limit is the variable to check for each individual garden — in most residential gardens, a single hobby greenhouse occupies a small fraction of the total garden area and presents no issue.
Listed buildings: Any property on the statutory list of buildings of special architectural or historic interest requires listed building consent for any external works, including greenhouse installation. Contact your local planning authority before proceeding.
Conservation areas and Article 4 directions: Some conservation areas and properties subject to Article 4 directions have Permitted Development rights removed or restricted. Check with your local planning authority if your property is in a conservation area.
National Parks, Areas of Outstanding Natural Beauty, and World Heritage Sites: Reduced Permitted Development rights apply in these designations. Height limits are typically more restrictive, and external materials may be subject to conditions.
Scotland, Wales, and Northern Ireland: Permitted Development regulations differ from England in these nations. Scotland and Wales have their own planning policy frameworks with different specific provisions. Always check the relevant national guidance rather than assuming England’s rules apply.
Leasehold properties: Some leasehold agreements include clauses about external structures. Check your lease before proceeding if you are a leaseholder.
If your greenhouse is a standard hobby size in a conventional residential garden in England, far enough from boundaries or within the 2.5m ridge height limit, planning permission is almost certainly not required. If you have any doubt at all — unusual plot shape, proximity to boundaries, listed building status, conservation area — a five-minute call to your local planning authority’s duty planning officer will give you a definitive answer. It is a free service and far better than installing and then receiving a retrospective enforcement notice.
This is the section that surprises many first-time greenhouse buyers. The assumption that a greenhouse needs a poured concrete slab or a professionally laid base is understandable — it sounds like a substantial structure requiring a substantial foundation. In practice, for the KLASIKA and BALTIC LT range, the ground anchoring system is built into the greenhouse itself, and the base preparation required is much simpler than buyers typically expect.
Every model in the range is designed around arch-driven ground anchoring. The steel arches extend below the greenhouse base level and are pushed or driven into the ground to a depth of approximately 35 centimetres. At this depth, the arch is anchored securely in the soil and the greenhouse structure is stabilised against lateral wind forces and uplift.
This system — arches driven directly into the ground — is the primary anchoring mechanism for the majority of models in the range. It requires no concrete, no ground screws, no post foundations, and no specialist preparation. It works on any reasonably firm soil — compacted earth, garden soil, clay, topsoil — as long as the ground is level and the arches can be driven cleanly to the required depth.
The practical consequence is significant: on a level grass or soil garden plot, a KLASIKA or BALTIC LT greenhouse can be assembled and installed in a single day on ground that requires no preparation beyond marking out and levelling.
Some models in the range include a 10cm steel foundation skirt as standard — a continuous perimeter rail at ground level that runs the full circumference of the greenhouse. The foundation skirt provides a defined boundary between the greenhouse interior and exterior, contains soil and growing media within the beds, provides a clean finished edge at ground level, and adds perimeter structural stability to the base of the frame.
Models with a foundation skirt included: KLASIKA ARCHED, STANDART KLASIKA, KLASIKA HOUSE, KLASIKA TUBE.
For these models, the installation sequence at ground level is: mark out the footprint, check level, drive the arches into the ground at the correct spacing, then fit the foundation skirt along the base perimeter. The skirt connects to the base of the arch sections and sits at ground level, creating the defined perimeter edge.
On an open ground or grass installation, the foundation skirt can simply rest on the surface with its connection to the arch sections providing stability — the arches driven into the ground carry the primary anchoring load and the skirt provides perimeter definition. On a hard surface, the skirt rests on the paving and the arches are anchored through gaps in the surface or bolted to the hard surface using expansion anchors.
Models without a foundation skirt have a simpler ground-level arrangement: the arches are driven into the ground and the greenhouse sits at surface level without a defined perimeter rail.
Models without a foundation skirt: BALTIC LT, KLASIKA BERNARD, KLASIKA DROP, KLASIKA SLIM, KLASIKA EASY.
For these models, the base preparation question reduces to: is the ground level, and can the arches be driven 35cm into it? If both answers are yes, no further base work is needed. The greenhouse goes directly onto the prepared ground surface — grass, bare soil, or compacted earth — with no additional base construction.
For buyers who want a neater internal floor arrangement without a skirt model, the practical alternative is to lay the greenhouse base on compacted gravel or a prepared level surface, and use the raised seedbed sets (available as accessories, sized to fit the interior width of each model) to define and contain the growing beds internally. This achieves a similar functional result to the foundation skirt without changing the model choice.
Grass or open soil (all models): The simplest and most common installation surface for the range. Arches drive into the ground through the grass or soil surface. The greenhouse sits at natural ground level. No preparation beyond levelling is required — though a thorough level check and correction before assembly is essential.
For skirt models (KLASIKA ARCHED, KLASIKA HOUSE, STANDART KLASIKA, KLASIKA TUBE), the skirt sits at the grass or soil surface and provides a neat perimeter edge. If you plan to create defined internal growing beds, the skirt makes this particularly clean and effective.
For non-skirt models (BALTIC LT, KLASIKA EASY, KLASIKA SLIM, etc.), the greenhouse simply sits on the grass or soil with the arches driven in. If you want a defined internal path and bed arrangement, raised seedbed sets of the appropriate width handle this entirely within the greenhouse.
Compacted hardcore and gravel: A popular base option that provides excellent drainage, a firm and clean internal floor surface, and good structural stability for the arches. Preparing a hardcore and gravel base involves: marking out the greenhouse footprint plus 30cm on each side, removing any topsoil or soft material, compacting a layer of hardcore or crushed stone, and topping with a layer of angular gravel.
This is the recommended base approach for gardens with soft, boggy, or waterlogged soil where the arch anchoring might not be as firm as ideal, and for buyers who want a clean, dry internal floor from the outset. Arches can be driven through the gravel and hardcore layer into the firmer ground below; if the ground is very soft, ground anchor bolts through the base frame provide additional security.
Paving slabs on a sand and cement bed: Provides a solid, level, well-drained base with a clean and durable internal floor. Suitable for models with and without foundation skirts. The preparation involves: marked-out footprint, compacted sub-base, sand and cement bedding layer, and accurately laid slabs checked for level across all dimensions before any slab is set.
For arch-driven models on a paved base, the arches drive into the gaps between slabs where the ground beneath is accessible, or — if the paving is continuous — expansion anchor bolts through the base frame into the slabs provide the anchoring. This is slightly more involved than the open-ground installation but produces a greenhouse on a base that requires no future maintenance.
The key requirement for any paved base is accuracy in the initial levelling. Out-of-level slabs produce an out-of-level greenhouse frame, and the consequences — doors that bind, panels that are stressed out of their channels — persist for the life of the greenhouse. Take the time to get the level right before setting any slab.
Concrete slab: The most substantial base option and the most permanent. A poured concrete slab provides an impeccably level, structurally robust floor that requires no maintenance and accommodates any greenhouse model. The preparation involves: excavation, compacted hardcore sub-base, formwork, and a poured concrete mix finished level.
A concrete slab is appropriate where: the ground is genuinely unsuitable for other base types (very wet, unstable, or made ground); the greenhouse is intended as a permanent structure and the base investment reflects that; the buyer wants the most solid possible base.
For arch-driven models on a concrete slab, anchor bolts cast into the slab or drilled in after setting provide the equivalent of arch-in-ground anchoring. For foundation skirt models, the skirt bolts to the slab perimeter.
The only practical disadvantage of a concrete base is the elimination of the option to grow directly in-ground, which some growers value for specific crops. Raised seedbed sets entirely resolve this if desired.
Timber frame base: A timber base frame — typically pressure-treated 4×2 or 6×2 timber in a rectangular perimeter — is useful for sites with very uneven ground or for buyers who want an elevated greenhouse floor without the permanence of concrete. The timber frame can be shimmed and levelled across uneven terrain and provides a fixing point for the greenhouse base frame.
Timber frame bases are most commonly used where concrete is impractical and paving preparation is too involved — garden sites with significant ground undulation, sloped plots where terracing is not desirable, or temporary installations. They require more maintenance than concrete or paving (timber rot management) but offer good flexibility.
Whatever base option you choose, the one non-negotiable requirement is that it is level — perfectly level, in all directions.
A greenhouse frame assembled on an out-of-level base will be distorted from the outset. The dimensional tolerances in a steel arch greenhouse are tight enough that even a few centimetres of cross-level will produce: doors that are racked and do not close squarely, panels that are forced into their glazing bars at an angle and stressed along one edge, arches that are not vertical and resist the panel fitting, and ridge bars that bow under the loading imposed by an unlevel frame.
None of these problems are catastrophic — the greenhouse will still stand and grow crops — but all of them are irritating and, in the case of stressed panels, potentially reduce panel lifespan. They are entirely preventable by careful levelling before assembly begins.
How to check level: A long spirit level — 1.2m or longer — used diagonally across the marked-out footprint in both directions gives a reliable level check across the full base. On soft ground, a taut string line between pegs at each corner allows level to be checked along each edge and across the diagonals. On paving or concrete, a long level placed on the completed surface at multiple points across the footprint confirms final accuracy.
How to correct level: On soft ground, the simplest correction is excavation — removing high spots rather than building up low spots, which can compress unevenly over time. On hardcore or gravel, adjustment of the sub-base material before topping gives good control of the final level. On paving, shimming the slabs during bedding is the standard technique.
Allow time for levelling before assembly begins. An hour spent getting the base perfectly level will save hours of frustration during assembly and years of minor operational annoyances thereafter.
Water management around and within the greenhouse is worth thinking about before installation rather than addressing retrospectively.
External drainage: The greenhouse roof sheds a significant volume of water in heavy rain. Guttering — included on skirt models and available as an accessory for others — channels this water away from the base of the greenhouse and prevents waterlogging at the arch entry points. Where a water butt is within reach, connecting the downpipe directly to it captures useful irrigation water for the growing season.
Internal drainage: Growing beds within the greenhouse should drain freely. On open soil bases, this is inherent in the ground. On hard bases (paving, concrete), drainage channels or permeable bed fill (gravel bottom layer in raised seedbeds) are needed to prevent waterlogging. Raised seedbed sets with their elevated sides also help manage internal water, keeping soil contained and preventing it washing across the hard floor surface.
Waterlogging risk: If the garden site is known to waterlog in winter — persistent standing water after heavy rain — this must be addressed before greenhouse installation. A waterlogged base will gradually undermine the anchoring of arch feet, cause progressive settling of the structure, and create an internal growing environment that is permanently too wet. Improving drainage of the site — land drains, perforated pipe drainage runs, or raising the greenhouse base on a well-drained gravel pad — should be completed before the greenhouse is positioned.
Before finalising your greenhouse position, run through this checklist:
Light and position:
Access and clearance:
Planning:
Base preparation:
How to assemble a polycarbonate greenhouse: what to expect, model by model
With the right site selected and the base prepared, assembly of a KLASIKA or BALTIC LT greenhouse is a manageable single-day or weekend project.
Our team is here to help you find the perfect growing solution.
