As an urban agglomeration, Milan presents a cold face. Its stoic, historical stone facades are handsome fortifications that echo the bombast of its Sforza castle. Adding to the city's stand-offishness, since the 1950s many mid-rise buildings have been covered in faceted ceramics designed by architect Gio Ponti to sparkle as the frequent rains pour down. It's poetic but hardly joyous.

One of the wonderful things about the annual Milan Furniture Fair – beyond the chance to see design at the zenith of excellence – is that for one week a year the iron gates to many otherwise impregnable palazzi are thrown open to welcome visitors to the launches and presentations and parties that happen all across town.

One fortuitous discovery earlier this month was the private garden of the 18th-century Palazzo Borromeo d'Adda. Its neoclassical facade gives onto the bustling Via Manzoni, but the secluded courtyard could be in the far-flung fields of Lombardy. Especially after the Brussels-based French florist Thierry Boutemy ratcheted up the bucolic several notches with his avenue of arches composed of herbs, citrus fruits, cucumber and Polish rye.

That mélange was no accident – these are the key ingredients of the luxury vodka brand, Belvedere, patrons of this delicious secret garden.

It's been 11 years since Thierry Boutemy shot to stardom as the official florist for Sofia Coppola's Marie Antoinette, starring Kirsten Dunst. Omnipresent, the flowers in the film play their own cameo, as vital to the drama as is Asia Argento as the blousy Comtesse du Barry. While they were in abundance, they were not used to excess.

"The 18th century is a time I have always been drawn to," says Boutemy. "And while it is usually thought of as a time of incredible excess, in floral terms if wasn't about sophistication, it was about an elaborate simplicity. In the film, we only used natural flowers, flowers that were used at the time." Anemones, ranunculus, poppies, periwinkles, wild roses – it wasn't the preciousness of the blooms that counted, it was the way they were deployed: asymmetrically, with extravagant imperfection. In splendid bloom but bound to die – in many ways Boutemy's bouquets symbolised Louis XVI and Marie-Antoinette's dramatic coda to the Bourbon line.

Natural understanding

"On the set of Marie Antoinette, Sofia barely spoke to me. But there was a natural understanding, as if we were on the same wave length. She is incredibly grounded, simple, normal."

These are words the florist, born in rural Normandy, applies also to himself. "People call me a floral artist or even just an artist. But I'm a florist. It's as simple as that."

A simple florist, perhaps, but one who now has an international portfolio of wealthy private clients who fly him around the world. A simple Norman who has embellished the catwalks of Dior, Lanvin and Dries Van Noten, and dressed the set of Mario Testino's cover shoot of Lady Gaga for American Vogue. Last year he supplied and arranged $100,000 worth of blossoms for the Florence wedding of Kanye West and Kim Kardashian.

Despite all the glamour, Boutemy remains grounded. For 25 years, he and his family have lived in Brussels, he says, because it's "a country town, a village. It's quiet and no one disturbs me."

It is also close to the world's largest flower market at Aalsmeer, on the outskirts of Amsterdam. More than 34 million flowers go to auction every day at Aalsmeer, with 3.7 billion roses and 1.7 billion tulips among the 12.5 billion flowers and plants sold a year. But you get the feeling many of Boutemy's flowers could be grown in his own garden.

Belvedere's interest in Boutemy stems from what the brand's president, Charles Gibb, notes is an affinity between the florist's rootsy approach to his craft and Belvedere's values of integrity, authenticity and terroir. "We work only with seven Polish farmers to cultivate our rye, and we're beginning to notice a different expression according to the field and microclimate the particular rye harvest comes from."

Described this way, it sounds almost rustic. I imagine Marie-Antoinette at the Petit Trianon, her nature retreat on the grounds of Versailles, rolling in fields of wild flowers and pretending she's a shepherdess.

Sophistication in simplicity: it takes great skill to attain, be that in a floral arrangement, premium spirit or even a rogue monarchy.