Nowhere is our bad attitude towards food better illustrated than by a recent incident in the home of Professor Phil Stevenson, head of trait diversity and function at Royal Botanic Gardens, Kew.

During a meal his teenage son threw a piece of cauliflower in the bin because it was a bit burnt. “I said to him, ‘Don’t waste good food’ and I took it straight back out of the bin and put it on my plate,” says Stevenson. “My son was like ‘OMG, eek’. But food waste and loss are a big problem.”

It was by no means the first time the academic at the scientific organisation and Unesco World Heritage Site has had to address food waste.

Kew is running a programme this summer called “Food Forever: the Future of Food in a Changing World”. It aims to encourage, says Stevenson, a fundamental shift in mindset and practice.

It wants to show visitors the often negative impact our diet and our attitude to food have on our environment and how we can change our behaviour. For example, by growing new species of vegetables, herbs and fruit at home that are more sustainable through needing less water and fertiliser and being more resilient to climate change.

The programme will include talks by scientists and chefs, films and immersive art exhibitions in which visitors can participate — including one that uses 3-metre-tall wooden trolls by the artist Thomas Dambo — to show us how we can cut food waste in production and consumption, starting in our own homes.

“I have a bee in my bonnet about food waste and loss and I do things in my own home to make the point to my kids,” says Stevenson. He recently ate some Marmite with a best before date of 2017. “It tasted fine.”

Our throwaway culture is part of a wider issue that should be terrifying us all, he says. Namely, how can the world continue to feed its population of 8bn and rising when we appear intent on destroying the biodiversity and climate that enable us to produce any food at all?

“Kew wants to use the programme to engage people on how important it is not to lose our biodiversity and, that if we do keep harming it, we will have less and less land on which to grow food while the world population continues to grow,” says Stevenson.

Now seems the perfect moment to do this. “We’ve always known about food source issues but it’s certainly the case that people are becoming more aware now of the [environmental] challenges we face,” he says.

On a global scale, this means looking at growing more sustainably. “We need to work out how we can produce our food in a more efficient way and to find more environmentally benign ways of doing that. We still rely heavily on synthetic fertilisers [whose nitrogen and phosphorus levels can harm the environment] whereas there are more natural, biological processes to produce food.”

One of Kew’s ongoing projects is studying the historic relationship between rice and soil microbes. Evidence suggests that rice may once have had beneficial soil microbes that helped them access nutrients in a similar way to how legumes use nitrogen-fixing bacteria to help feed themselves. Rice is the second most consumed food on the planet but is heavily dependent on synthetic fertilisers, so rediscovering the microbes would have a huge impact. Efficient pest and disease control is also crucial.

“One-third of the food we produce globally is never eaten due to pests in the fields while growing, or poor storage and transport,” says Stevenson.

Part of growing more sustainably is to offer a wider diet. Diversity is as important for the planet as for our own health and we should be looking for alternatives to staples such as wheat, maize and rice. Especially in the light of Russia’s invasion of Ukraine, which illustrates the danger of relying on a handful of countries to supply a small number of staples — Russia and Ukraine are leading exporters of grain and fertilisers.

Kew says there are more than 7,000 known plant species that we could be eating rather than sticking to the handful we do consume. For example, African crops that are established and nutritionally important but are underutilised include a legume called lablab (Lablab purpureus); bambara nut (Vigna subterranea); finger millet (Eleusine corcana); and marama bean (Tylosema esculentum).

Lablab, found in east Africa and drought tolerant, “is a good example of a food that people could grow more widely in other countries with that climate and maybe one day in the UK if we get hotter”, says Stevenson.

In Ethiopia, staple foods include enset (Ensete ventricosum) the “false banana”, which is versatile, easy to grow and could be produced more widely across Africa.

In the UK we can help by growing new species of vegetables at home, says Helena Dove, head of Kew’s kitchen garden. “When I arrived four years ago I just grew what had been done before. But things have changed and one of the changes we’ve had is our hotter, wetter summers bringing more potato blight,” says Dove.

The blight is a disease that occurs in warm, wet weather and hits main crop potatoes, a vital source of starch that can be stored over winter. Dove is experimenting with alternatives sourced from the Andes, from where the potato originated: ulluco (Ullucus tuberosus); mashua (Tropaeolum tuberosum); oca (Oxalis tuberosa); and yacón (Smallanthus sonchifolius).

Her aim is to manipulate the plants’ reproductive cycles so they will grow successfully in the UK. She has had to rule out ulluco because of pests and diseases.

Mashua is a climbing nasturtium, so a space-saver. It produces edible tubers with a mustardy taste, peppery leaves and flowers. “It grows incredibly fast and it’s easy to grow,” she says. “If you plant it out after the last frost you’ll get your crop about the same time as main potatoes and, like them, it stores well.”

Second on her list is oca. “One of the reasons we don’t grow oca everywhere in the UK is that we’re still trying to breed them to get the tubers big enough,” she says.

The problem is that oca is a photoperiodic plant that requires short days of 12 hours or less for tuber formation, so will not start to grow until after the autumn equinox in September.

“We’re still trying to breed that out of them, though oca has come a long way,” she says. “Its leaves are lovely and its tubers taste lemony and you can get a good harvest out of them. It needs warmer weather than for potatoes but our summers are getting longer and warmer.”

Other vegetables we could be growing from seed in our gardens include tomatillos; cucamelons; sweet potato cultivars bred for the UK summer; and agretti. Perennial crops whose deep roots make them more resilient to climate change include asparagus, rhubarb, globe artichokes, perennial kale, nine-star broccoli and Egyptian walking onions.

Dove also grows leaf crops that 10 years ago would not have survived in the UK climate, and whose seeds are available at a reasonable price. Callaloo (amaranthus), a nutritious green that originates from the Caribbean, can be bought for £2 for a packet of 1,000 seeds.

“It’s drought tolerant so it’s sustainable,” says Dove. Malabar spinach (Basella alba) “was not readily available here until recently because the UK was too cold and it wasn’t popular to eat. Now it’s a viable crop.

“Seeds make a great present, you could give someone a packet and keep them in food for a year. I’m the cheapest Christmas present-giver out there,” says Dove.

Dove and Stevenson are optimistic that the Kew programme will force a rethink. “It’s not that long ago [in history] that we all refused to eat potatoes, chillies or tomatoes. Staples in Africa are now foods that come from South America. So food habits can change,” says Stevenson. Even a teenager’s horror of singed veg.

“Food Forever: the Future of Food in a Changing World; May 21-September 18; kew.org

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