"There are some colours I see in music. I relate music to specific colours, and then relate it to each one of the festival's three days." I'd asked Ruggero Pietromarchi how he curates Terraforma, the festival he runs each year from a gorgeous green space on the outskirts of Milan. "There's a chromatic correspondence between some music some days, and even some hours of the day. For example, I would never imagine a yellow during the night."

We were speaking in a London café a few weeks after PLO Man had brought Terraforma's fifth edition to an ecstatic close. Ruggero's gentle Italian accent could just be heard over the clank of coffee cups. "Another important point is the frequencies in terms of how the sound is produced," he went on. "If it's a turntable or if it's a microphone or if it's some acoustic instrument—it's important to set up the right moment for the performance. And a third element is the importance of the human being. I try to meet personally all of the musicians, to know their background and how they approach their own artistic process. This is very important to me."

One of the first things anyone who's been to Terraforma will talk about is how this all unfolds. Terraforma has three stages but only one hosts a performance at any given time. Ruggero told me that Labyrinth, the long-running Japanese techno and experimental festival, was the main inspiration for this. But where Labyrinth is about communion around a single stage, and a similarly spirited event like Unsound offers a dizzying array of choice, Terraforma is about sharing the same literal and figurative journey. Walking between stages for the next performance is a key part of a ritual, a feeling that's only intensified when you arrive to find something unexpected.

"I really like simplicity," Ruggero said. "This idea is often missing in the useless complexity of nowadays."

On the Saturday of last year's Terraforma, I met Ruggero at the festival's second stage, its chunky dub soundsystem looming behind us. The speakers and the DJ booth were framed by rows of trees and, on the opposite side, a bar built from wood that served organic local wine. Donato Dozzy was busy untangling cables for his performance later that afternoon. Ruggero explained that they met back in 2011, when Dozzy asked him to curate a sound installation at the Venice Biennale. Dozzy is basically a Terraforma resident, having played every year. "I like the fact that the festival looks like an open-air experimentation laboratory," Dozzy told me over email, "where each Terraformer acts as a collaborator."

Dozzy memorably closed the 2017 edition with an ambitious DJ set of broken beats, hip-hop, drum & bass and some gabber. (RA later booked him to play in this style as part of its Alternate Cuts event series.) For Dozzy, though, it was a bittersweet moment: "I collapsed after I just finished my secret set... and suddenly the crowd turned into a group of kind and helpful people, sincerely worried for me but still, somehow, raving about the set."

I asked Ruggero why Dozzy had become so integral to the festival. "I love his music," he said. "It gives me something very unique. It's a matter of frequency, we balance on the same frequency. I love his way of approaching his job. It's also his legacy, in a way. He's a generation older than me. He represents a very specific scene and culture and values."

What are those values? "From one side, very professional. The way he works is super specific. At the same time, he belongs to ideas. He strongly believes in ideas over strategies."

The same could be said of Ruggero, whose general vibe is more art curator than festival booker. His mother was an art history professor, his father a French literature professor, and there were sculptors, filmmakers and photographers in his immediate family. This deep immersion in the arts has helped shape his worldview, and it's an infectious part of his personality. At times he discusses Terraforma (and music and art generally) in almost spiritual terms. He told me that some of the best feedback he received about the festival last year was that it "regenerated" and "refreshed" people's daily lives with new ideas and new energy.

Ruggero generates his own new ideas under the umbrella of a company called Threes, which produces Terraforma along with cultural happenings in and around Milan. "A series of site-specific concerts geared to provide a musical getaway to some of the most interesting locations of the Italian cultural heritage," is how Threes' website describes one of its ongoing projects. "The aim is to create a dialogue between the involved spaces and performances, giving birth to unique combinations." These have included a performance by the avant-garde composer William Basinski at a church lit with an installation by the late American artist Dan Flavin, and the Japanese group Boredoms playing at the HangarBicocca museum among large-scale Anselm Kiefer paintings.

Ruggero Pietromarchi

Although Terraforma doesn't sit at such an overt intersection between art and music, it is obviously concerned with matters of Italian cultural heritage, which it deals with under a concept of "sustainability." When Ruggero and Leone Manfredini, one of Terraforma's project managers along with Nicola Giuliani, talk about sustainability, they mean it both in the sense of environmental responsibility and historic preservation. The festival is committed to reducing its overall waste and energy consumption each year, and has nice little touches like the ubiquity of recycling points and personal pouches for people's cigarette butts. (Terraforma was recently awarded the title of "most improved" by the nonprofit organisation A Greener Festival, who worked with 35 European events last year.) But just as vital is Terraforma's collaboration with Villa Arconati, the grand 17th century building whose gardens the festival takes place in.

"One of the main goals of Terraforma, along with presenting a three-day musical journey, is attempting to create an environment in which music, nature and cultural heritage profoundly interact with each other and with our visitors," Manfredini told me. "Sustainability represents one of the most direct mediums to reach this purpose." Terraforma has a commitment to help restore and maintain Villa Arconati's gardens, which includes quirky restoration projects such as the labyrinth. The corridors of plants, arranged in interlocking circles, that now stand in the gardens were inspired by the original architectural plans from the 1700s.

The Milanese architect who drew up those plans, Marc'Antonio Dal Re, would have been astounded to see how the labyrinth was being used in 2018. On the Friday night of the festival, Plaid & Felix's Machines presented a beguiling live show that was an ideal use of the space. In the central circle stood a roughly 20-foot-tall installation built from differing mechanical instruments that looked like something out of Mad Max. The trio controlled things from a nearby desk, while the audience tried to figure out what, exactly, they were seeing and hearing; depending on where you were standing, the labyrinth's foliage and the drifts of a smoke machine distorted the view. Two days later, there was a similar sense of excited bafflement over the performance by Vipra, an Italian act who have released on Presto!?, the label Ruggero runs with Lorenzo Senni. A video shot by Boiler Room captures the oddball, performance-art feel of a show that featured wigs, raised platforms and a drum suspended by a wire. Ruggero said he likes to use the labyrinth around dusk, the point in the day when people's vision becomes impaired and the strangeness of the night is creeping in.

Ruggero's mind seems to be constantly bubbling like this, developing fresh ideas and projects. When we caught up over the phone last month, his recent activity included music curation for a private Nike event; production of a sound collage for the new space of Massimo De Carlo, the famous Milan gallery; curation work for a festival called NeXTones in Northern Italy; compiling the second edition of Raster's SICHTEN series, following on from Frank Bretschneider; and an unspecified project with Lorenzo Senni in Matera, the Italian town with a fascinating but troubled history that's the 2019 European capital of culture. His fluency in multiple disciplines makes a to-do list like this seem completely natural.

At the festival last year, Ruggero told me about his growing interest in the human voice, which some months later has manifested in Terraforma's concept for 2019: language. "I see Terraforma as a world in itself," he said last month. "It has its own landscape, its own community, so I thought it also deserves its own language." The respected designer, sculptor and painter Nathalie Du Pasquier has designed this year's artwork, as well as an alphabet of 21 symbols that will appear on flags across the festival site. Ruggero said how, despite being the most famous designer they've collaborated with, working with Du Pasquier was very smooth, and she became heavily invested in the process. There's a bright, vibrant quality to Du Pasquier's design, but Ruggero said he also sees the concept as a rallying call to "speak up" about the current political and social situation. Electronic music, he said, is often voiceless and escapist, but in this moment "we cannot allow ourselves to be so abstract."

Laurie Anderson, the much-loved multi-disciplinary artist, who Ruggero described as a "big inspiration," will present a piece called "The Language Of The Future" as one of the key performances at Terraforma 2019. Ruggero sent me over some thoughts on the other main bookings. You'd expect there to be an element of simply filling out a suitable lineup when it comes to booking a festival, but his process sounds more like a poetic personal odyssey. "Daniel Higgs is a legend to those who know his work as the Lungfish frontman and as a tattoo artist," he said. "It was one of his latest solo releases [The Fools Sermon], though, that got me to invite him to Terraforma." He described DJ Stingray as "a friend before a myth," who is "one of the most contemporary voices from the Detroit techno legacy." Mica Levi, he said, is an "absolute genius" composer, whose "style and approach are unique in a very unpredictable way, and that's why I'm not exactly sure what to expect from her DJing." As for Caterina Barbieri—"seemed to me like a natural choice to invite her to open the festival before Laurie Anderson's performance. We're discussing a specific performance that will give shape to her patches as an alphabet."

For all its cerebral underpinnings, Terraforma is, at times, an incredible party. I attended in 2017 and 2018, and on both occasions Paquita Gordon's afternoon set at the dusty second stage captured the festival's hedonistic essence. When they're at their most engaged and unencumbered, the crowd at Terraforma has a loose, hazy, psychedelic vibe. (After her set in 2017, Suzanne Ciani told me that Terraforma reminded her of the hippie gatherings she went to in the '60s.) On the Sunday afternoon last year, after treating the crowd to a winding selection that took in dub, jazz, house and drum & bass, Gordon, who was celebrating her birthday, joined her friends in front of the DJ booth as they sang "buon compleanno" and let off sparklers and confetti.

Charlemagne Palestine, Paquita Gordon, Suzanne Ciani

"I've played at the festival since its first edition," Gordon said in the interview for her RA podcast, which was conceived in the spirit of her Terraforma sets. She mentioned Ruggero's special "inspiration and vision" and said, "What I most like about it is the fact that Terraforma represents a deep statement from my generation: after years of growth and observation of the outer world, we now have the responsibility to shift those paradigms left by our parents and grandparents."

Although all very different sonically, the bookings of Powder, Vladimir Ivkovic, Nkisi and PLO Man last year show the type of nonstandard dance floor experiences that Ruggero likes to create at Terraforma. PLO Man, who closed, played it the straightest, but after roughly 40 hours of sometimes challenging music across three days, hearing feel-good bangers like KC Flightt's "Voices" and Floorplan's "Funky Souls" under a disco ball, which had been put up especially for the set, was a welcome tonic.

The people who don't camp at Terraforma reach the festival site each day by walking through Villa Arconati's baroque front entrance, over some crunchy gravel, down an idyllic green path and past the space where the talks and interviews are held, before eventually arriving at the clearing that houses the dazzling main stage. On that green path, being interrupted continually by friends and well-wishers, Ruggero told me how he's achieved the musical balancing act that sets Terraforma apart. "I think we have managed pretty well," he said. "The programme we have is really experimental, it's not for everybody, but what we've managed to do is create a setting where this music can express itself, even to people who normally wouldn't be exposed to this kind of music. That's our challenge, to ourselves and to the audience."