‘Look at that!” Annie Sprinkle says, marvelling at the blossom of a cherry tree. “Flowers are tree genitals. Basically, you’re looking at porn.” I’m in San Francisco and the pioneering, X-rated feminist is taking me on a walk – an “ecosexy nature walk”. We’re in Bernal park, a place the porn star-turned-controversial performance artist once deemed to be “the clitoris of America”. And now she has come up with a bold new idea: ecosexuality. The main premise is that you see nature as your lover and not as your mother. You might give your mother a hard time and she’ll put up with it, but with a lover it’s a question of give and take and, ecosexuals believe, that’s just what the planet needs right now. It neatly sums up how ideas of eroticism are expanding within the sexual avant garde. And rather than focusing on conflict and anger, it prides itself on joy and positivity.

“We’re trying to make the environmental movement more fun and diverse” Sprinkle, 62, tells me, pointing to a suggestively exuberant hibiscus stamen. Certainly a nature walk with a former porn star who keeps encouraging me to find my Eco spot (or E-spot) is much more exciting than anything I’ve seen on Countryfile or read in a Naomi Klein book.

‘We’re trying to make the environmental movement more fun and diverse.’ Photograph: Julian Cash

Sprinkle and her partner, Beth Stephens, co-creator of the ecosexual movement and an art professor from the University of California, Santa Cruz, have staged about 15 large-scale weddings to the likes of the Earth, the moon, the sun and the sea. They “came out” as ecosexuals in 2009 after their wedding to the Earth. Until then, the word “ecosexual” had been kicking around as an obscure dating category. But now, with the advent of Donald Trump’s presidency, things have moved up a gear. On 18 and 19 May, Sprinkle and Stephens will be hosting their fourth and biggest ecosexual symposium yet. Scientists, artists, sex commentators and more than 300 ecosexuals from around the world will be congregating at the University of Santa Cruz to enjoy performances and debates, and muse on the intersection between sex and ecology. Peaches, the cult musician and ecosexual champion, has written a poem called Dirt to mark the occasion (“Dirt is a wonder, dirt is real, dirt is precious, dirt gives us breath”); Luke Dixon, co-founder of the UK’s Theatre Nomad will be providing “ecosexy Shakespeare”; and Sprinkle will be demonstrating “grassilingus” on the university’s lawn. There will be a trailer for Sprinkle and Stephens’s new film, Water Makes Us Wet, about the pleasures and politics of water in California, which will premiere at this September’s Documenta festival in Kassel, Germany.

A few years ago, Sprinkle and her band of nature anthropomorphisers might have been dismissed as hippies. But, in a country whose president considers global warming “bullshit”, the ecosexuals don’t seem so weird. And yet the movement does bring up some problems. Most cultures around the world have traditionally seen the Earth as female, but Stephens insists that nature “can be trans”. I, personally, first heard nature referred to as “they” at Queer Spirit festival in Somerset last summer. As a student of Romance languages, I realised I had become a stick in the mud for the sun being masculine and the moon and the Earth being feminine. Stephens has a different take. “In a misogynistic society, when people imagine the Earth as a “she”, they think she is less important than a he. So, the mostly all-male polluting corporate heads think they can treat the Earth badly. This is basic eco-feminist thinking. In any case, Sprinkle suggests we shouldn’t sweat the finer details. Ecosexuality is a burgeoning queer identity for some and a way to get more primal in your sex life for others, but you don’t have to be a gender studies student to join the club. “Most people get sensual pleasure from the smell of a flower. We just want people to love the Earth more.”

• The Explorer’s Guide to Planet Orgasm by Annie Sprinkle (Greenery Press, £11.99) is published on 8 Jun. To order a copy for £10.19, go to bookshop.theguardian.com or call the Guardian bookshop on 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99.