Romans in togas, shepherds in saunas and the Bridgerton garden in bloom … my wild day at Chelsea flower show

Has architecture taken over the bloom bonanza? Our critic finds an elfin treehouse, a pixie grotto, a Roman villa and a £160,000 shepherd’s hut (with spa) now competing with the delphiniums

A gigantic Chinese dragon made of gnarled chunks of driftwood towers over a display of bog plants, puffing steam from its nostrils and clutching a ceramic pearl that gushes with water. Nearby, men dressed in togas patrol the courtyard of a pretend Roman villa, where simulated rain pours into the garden from a pantiled roof. Around the corner, a waterfall cascades down an artificial rock face, creating an arresting backdrop to a display of luxury outdoor sofa cushions.

Welcome to the RHS Chelsea flower show, a surreal phenomenon that has gone from an annual fair of prized blooms to a multimillion-pound Disneyfied spectacular, where the flowers now struggle to hold their own against ever more elaborate pieces of set design.

Every year, in the space of just three weeks, the grounds of Christopher Wren’s Royal hospital in London are transformed into an unrecognisable wonderland of horticultural fantasies. It is a place where elfin treehouses compete for attention with pixie grottos, and sculpted clay stupas loom above moss-encrusted ruins. It feels like wandering around a themed food court, with Moroccan tiled courtyards jostling with Japanese bridges, thatched Burmese stilt houses vying with Welsh dry-stone walls. The cuisine on offer might not be as international, but you can wash down the global garden safari with a £15 Pimm’s.

Begun in 1913, in a modest marquee, the Chelsea flower show has mushroomed into a town-sized endeavour. It has become a festival of terraforming as much as flowers, seeing more than 2,000 tonnes of soil moved around the 11-acre site each year, and hundreds more tonnes of rocks, concrete, trees and scenery trucked in from miles around – all for just five days of floricultural theatre. Now, for the first time, this year there is a “green medal” for the garden with the lowest carbon footprint, which feels a bit like holding an exhibition of bonfires, then awarding a prize to the one that produces the least smoke.