Designing a Hogwarts Greenhouse

It started as the kind of day-dream you have over coffee — what would a greenhouse look like if it belonged to Hogwarts rather than a kitchen garden? The films already gave us a beautiful one: Professor Sprout's glasshouse with its great Gothic arch, the verdigris lanterns hung from the ribs, the trays of Mandrakes and the students in their earmuffs. I kept coming back to that arch. I wanted to draw the whole building it implied — to take the day-dream and give it real heights and gutters and a place to stand. So I did, and then I let it run all the way to a set of antique survey plates, as though the thing had been built in 1874 and properly recorded.

The plan I kept coming back to is long and narrow — 14.4 metres along the rear elevation, broken into five bays, with a great pointed-arch gable rising in the middle of the south front like the west window of a small chapel. The two flanking ranges run lower and lean into it. Stone where it meets the ground, glass everywhere above. The proportions matter more than the magic; get the proportions wrong and no amount of dragon will save it.

Because of course there are dragons. A wrought-iron finial at every gable peak — Draco dormiens nunquam titillandus, after all — and between them a run of iron ridge cresting, the kind of spiky Victorian frill that catches frost in winter. The roof itself is leaded glass held in a grid of wrought-iron glazing bars, and the gable is filled with Gothic tracery: trefoils, quatrefoils, a rose at the apex. The sort of thing that throws complicated shadows across the floor by mid-afternoon.

I worked it up as a real set of drawings — four elevations and a section — heights and all. Ground level at zero, a stone plinth running up to +0.600, the eaves at +4.350, the ridge at +7.650. The glazed wall stands a full five metres before the roof even begins. Stone pilasters with carved capitals divide the bays; a stone abutment joint shows where the whole thing leans companionably against an existing castle wall, with the eave gutter turning the corner and a rainwater pipe dropping down beside it. Even a magic greenhouse has to deal with Scottish rain.

The section is where the day-dream got the most carried away. Cast-iron columns with ornate capitals march down each side, carrying vaulted iron ribs that meet at a cast-iron ridge beam nearly nine metres up. Gothic tracery spandrels fill the haunches. A hanging lantern down the centre — the verdigris one from the films, more or less. Wooden potting benches with a raised edge run the length of both sides at 3.45m bench height, already crowded in my head with terracotta and trailing things, and the floor is stone flagging with a central drainage channel and a cast-iron grate down the middle — so you can hose the whole place down and not think about it.

A secondary timber door on the east end with wrought-iron strap hinges; the main arched entrance under the south gable with a ring handle and a quatrefoil light above it. Pilasters with finials flanking the door like sentries.

None of it will ever be built, which is rather the point. It's a building for a place that doesn't exist, drawn at 1:50 with proper title blocks and a Hogwarts crest in the corner, as though someone at HB Architects had been commissioned in earnest. But the discipline of drawing it — setting real heights, making the gutters return, deciding where the water goes — is what turns a day-dream into something you can almost walk into. I'd happily potter in here for an afternoon. I'd grow something difficult on purpose, just to have an excuse.

The drawings

The working set — four elevations and a section, at 1:50.

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📐 Download the reconciled blueprints (PDF) — the whole thing redrawn to a single coordinated scheme, issued for construction at 1:100. Figured dimensions govern.