Someone has lost their ball. At least that’s how it looks in Jardín Botánico Regional de Cadereyta, as if a golfer has teed off badly and somehow landed their shot here in the dust, among the cacti.

In fact, the small white sphere is a rare type of cactus, unique to the Mexican state of Querétaro. “It’s micro-endemic. There is nowhere else in the world you can see it,” says guide Oscar Zepeda, introducing us to Mammillaria herrerae. “It grows in just one square kilometre. There are only 250 left in the wild.”

There are more than 100 types of cactus at Cadereyta’s Botanical Garden, out of 669 species found across Mexico – including stubby biznagas, towering órganos and spiky-eared (and widely eaten) nopales. I’d thought cacti might be a prickly subject in Mexico, one of several clichéd perceptions of the country. But they inspire real pride.

“Cacti give identity to Mexico,” Oscar tells us. “Sixty per cent of all cacti come from Mexico. What gives us identity is not the cactus but what we make from it: ice cream, jam, salads, cosmetics, medicine, water… Cacti are remarkable.”

Cadereyta is one stop in a brand new trip through the plant life and gardens of central Mexico, taking in Mexico City and three surrounding states (Querétaro, San Luis Potosí and Morelos). The itinerary is so new, it was still only at the “ideas” stage when I did it; not only was I the first person to complete the tour, but I helped the company decide the journey and the places to visit. I’ll take the opportunity to coin it Mexico’s “Garden Route”.

There are more than 100 types of cactus at Cadereyta’s Botanical Garden Credit: getty

It could be a growth area. “I’ve worked as a tour guide for 30 years and it’s the first time people have come just to visit our gardens,” guide Sonia Waldo tells us in Mexico City. “People know about our churches, pyramids and beaches. This is another view of Mexico.” With this week’s Chelsea Flower Show fresh in our minds, it’s worth remembering that Mexico offers an alternative adventure through its little-known gardens, from surrealist marvels and “succulent” forests to peaceful canals and vineyards.

Our first stop is Chapultepec Forest in Mexico City, the oldest park in Mexico. At 1,695 acres, it is five times larger than Hyde Park. Most tourists go for the Anthropology Museum or Chapultepec Castle. Few visit the Botanical Gardens, or know they exist.

We stroll through peaceful displays of cacti, sprawling maguey and massive agaves (the plant that gives the world tequila and mezcal). There’s a “mini-ecosystem” for bees, highlighting the threat of extinction, and another for grasshoppers, a vital food source in Aztec times and still eaten today in Mexico.

“Smells wonderful,” Sonia hums, as we examine medicinal plants such as lemon balm. “Plants have been very important since Aztec times and even before. The pre-Columbian civilisations had advanced knowledge of medicine from plants and herbs.”

Chapultepec Forest in Mexico City is the oldest park in Mexico Credit: getty

Next morning, we drive south to the Botanical Garden at Unam (National Autonomous University of Mexico), close to Mexico’s Olympic Stadium. Pathways of jagged black lava rock weave through a forest of succulents, plants such as cacti, agave and maguey that store water, a vital talent in Mexico’s hot, dry landscapes. I watch hummingbirds extract nectar from agave flowers. The ground rustles with scurrying lizards. A black tarantula eyes us from the path.

There is no obvious danger in the grounds of Museo Dolores Olmedo, near Xochimilco, the former home of Dolores Olmedo, a wealthy businesswoman and mistress of the artist Diego Rivera, Frida Kahlo’s husband. Her house, previously a 16th-century convent, contains the largest collection of Rivera paintings in the world, as well as works by Kahlo. There are sculptures throughout the gardens, including Diego Rivera’s head and Dolores with one of her beloved black, hairless xoloitzcuintle dogs. Regal blue peacocks roam neat lawns.

Later, we reach the waterways of Xochimilco, passing far beyond the main tourist zone. Instead, we board from a bridge in Barrio La Santísima, with captain Benigno Ibarra using a wooden pole to manoeuvre the engineless boat through silent canals where white herons stalk through water lilies.

Herons stalk through waterlilies in Xochimilco Credit: getty

“Welcome to the unknown area,” Dionisio Eslava smiles, as we step off. “Everybody has seen the tourist area and they think it’s the last remaining part of Xochimilco. Very few people come here.”

Dioniso is the president of Umbral Axochiatl, an association working to revive chinamperia, one of the oldest types of agriculture in the world. The “land” we’re standing on is a chinampa, a “floating mattress” of soil with water beneath and on all four sides. Chinampas were used to grow corn and other crops by pre-Hispanic civilisations – the Xochimilcans and, later, Aztecs. Without the chinampas, Mexico City wouldn’t exist.

Before the Spanish, there were 20,000 chinampas. Now, there are just 2,000 along 114 miles of canals. “It’s a way of preserving our identity and culture,” Dionisio says of the restoration project, while speedily embedding young maize plants. “Chinampas give better food, water, air and a better environment. We will depend on them in the future.”

The waterways are also the original home of axolotls, sci-fi-worthy salamanders. Fifteen of Mexico’s 19 axolotl species are in danger of extinction from loss of habitat, pollution and the introduction of predatory fish. Largely wiped out in the wild, they are now cultivated in laboratories. “It’s important to preserve them,” says Karina Molina, a biologist with Axolotitlán. “It’s a species that’s endemic and emblematic of Xochimilco.”

Axolotls are sci-fi-worthy salamanders Credit: getty

Axolotitlán works with Umbral Axochiatl to create pristine water channels free of tilapia and carp, which eat axolotls and their eggs. The cleaner water also benefits plants – so it’s a win-win.

We spend a night in the colonial city of Querétaro, north of Mexico City, driving out next day into rural parts of the country. Along the way, we pass Peña de Bernal, a striking 474yd chunk of rock, the world’s tallest monolith and, according to rumours, the site of extraterrestrial activity. At Viñedos Azteca, we walk around the hacienda’s lakes and along rows of one of my favourite plants: vines.

Guadalupe Valley in the north of Baja California has garnered attention as the “new Napa”, but Querétaro’s vineyards are almost unheard of internationally. In a tasting room, we sample Cahuayo, a fruity blend of cabernet sauvignon and malbec, and Apertura, a refreshing vermouth. “We’re at a new stage,” says sommelier Rafael Barcenas, pouring wine at the bar. “Back in the day, there were just 10 wineries; now there are more than 40 in Querétaro. The name is growing.”

We drive on to Cadereyta’s Botanical Garden on the edge of the colonial city. Some 945 Mexican plant species are officially in danger of extinction, including Mammillaria herrerae. “The primary reason to create this garden is to make people value our resources,” Oscar explains, guiding us through an avenue of tall órganos to a little “golf ball” outside the greenhouses. “That way we can educate people to take care of them.”

The colonial city of Querétaro Credit: getty

Exploring the diverse array of cacti, agave and maguey, we gradually work our way up hillside trails to a series of waterfalls, comically signposted “The Trickles”, for views across a sun-beaten landscape of hills and cactus clusters.

The road snakes through a semi-desert landscape in the afternoon, mountains covered with scrub and candelabra cacti giving way to the pine forests of the Sierra Gorda. Crossing into the state of San Luis Potosí next day, we reach the town of Xilitla, made famous by one of Mexico’s most celebrated gardens: Las Pozas, a surrealist garden created by Edward James, a Scottish poet, artist and wealthy patron of Salvador Dali and René Magritte.

We stay at Hotel Posada El Castillo, the house James lived in, sleeping in Don Eduardo, James’s former bedroom. In the lounge there is a James painting, featuring a demonic sort of merman.

We enter Las Pozas (“The Pools”) early next morning, concrete snakes standing guard along the Avenue of Seven Deadly Sins. James called the gardens his “Surrealist Xanadu”, spending 22 years, from 1962 until this death in 1984, creating more than 50 concrete structures across 80 acres of tropical forest, pools and waterfalls. With its fantastical towers, bridges, platforms, arches and columns, it’s like a Lord of the Rings set.

Las Pozas, a surrealist garden created by Edward James Credit: GETTY

We explore the labyrinth of pathways, accompanied by the sound of rushing water and the crackle of insects. An iron door, decorated with red stars, creaks open into a magical, temple-like structure, the Stairway To The Sky. Elsewhere, a series of waterfalls has been augmented with arches and a little shelter, but nature has produced the real masterpiece: water cascading down tiers into a rock pool, with Blue Morpho butterflies and Montezuma oropendolas flying above.

Other sections of the gardens have a rough, unfinished look and some ideas fall flat. From an eccentric artist, I’d expected more strangeness. The previous afternoon, we had visited the Leonora Carrington Museum in town, filled with her eerie bronze sculptures mixing human, animal and mystical elements. Several of her large sculptures are sitting unused in a yard in town. That no one has brought the two together seems a missed opportunity.

Via Mexico City, we head south again into the state of Morelos, a sign over the highway welcoming us to Cuernavaca, the “city of the Eternal Spring”, so-called by the Spanish for the year-round good weather. Our final garden is Jardines de México, opened in 2014. A giant peacock, decorated with 3,600 flowers, stands at the entrance, close to beds of white, pink and purple petunias.

With 51 acres, this is the largest floral park in the world. We enter the Labyrinth Of The Senses, a maze of sculptures, from a giant blue hand to a voluptuous woman balancing precariously on a ball. In the Orquidiario, waterfalls trickle into lily ponds beside rows of orchids. The Italian garden has statues and fountains; red wooden bridges, Shinto shrines and bamboo forests grace the Japan garden. A cactus area has more than 200 species, from little viejitos (“old men”), coated with straggly white hair, to a giant candelabra which Sonia estimates to be around 300 years old.

Gardens like this, and those at Chapultepec or Cadereyta, are increasingly important. “They can make us think about what we are destroying, what we are losing,” Sonia suggests. “We have examples in Mexico of how big cultures disappeared because they destroyed their environment or ecosystem, as we are still doing now. We can learn so much from nature.”

Essentials

Journey Latin America (020 8747 8315, journeylatinamerica.co.uk) has a 12-day Mexico holiday covering Mexico City, Cuernavaca, Querétaro, Cadereyta, Jalpan de Serra and Xilitla from £4,641 per person, including flights, transfers, garden excursions and mid-range hotels on a B&B basis.British Airways flies from London to Mexico City from £624 return. To book, see ba.com/Mexico or call 0844 493 0787.