Sun-tanned cauliflowers and knobbly spuds - the heatwave veg that's good to eat

Would you buy a cauliflower that looks like it's been sunburnt or a cucumber that's curled back on itself?

Farmers across the UK are grappling with one of the driest, hottest growing seasons in decades. Repeated heatwaves after a warmer than usual spring have led to predictions of the worst harvest since records began.

The heat is not only affecting how much produce is grown, but also how it looks.

Retailers usually reject fruit and vegetables that don't meet strict guidelines on size, shape and colour. But with supplies under pressure, many are now expected to loosen those rules rather than risk empty shelves.

That means shoppers could start seeing smaller, wonkier or oddly coloured veg on the shelves in the coming weeks - and sellers and growers say it's still good to eat.

Cauliflower is one of the most affected vegetables in hot weather because it needs lots of water.

Its heads are usually shielded from sunlight by the leaves, but in this year more light is reaching them and turning them yellow.

Emilie Vanpoperingh, co-founder of Oddbox, a subscription company that sells surplus produce that supermarkets reject, said it is "purely a cosmetic defect" and the plants taste exactly the same.

She said Oddbox acquired 6,000 cauliflower heads last week that were too dark for supermarkets to sell.

Growers are reporting that their water reserves are depleted, Vanpoperingh said, which means the cauliflower and broccoli family of brassicas will experience slower growth, leading to shorter supplies.

That short supply means retailers may soon start stocking "sun-tanned" cauliflower because "their biggest nightmare is empty shelves", she said. "They want to make sure that they've got availability of produce all the time."

Growers are also reporting cucumbers that are coming out misshapen, with some bending back into a spiral.

That is because the plants are grown in greenhouses which overheat in the high outdoor temperatures, causing the plants to become stressed, Vanpoperingh said.

"Even if they get the irrigation then it's just extreme heat, which means the plant is not able to grow anymore."

John Harper, a farmer in Worcestershire, grows pak choi for Sainsbury's, Aldi and Co-op, and has discarded more produce than usual this year because of tiny holes made by pests.

Flea beetles thrive in hot, dry conditions, and farmers are no longer allowed to use as many pesticides as before, meaning net covers are Harper's only defence.

Supermarkets' strict cosmetic rules mean "one tiny little hole can render the plant useless", he said, but some have temporarily loosened the rules.

"We've been working with them through this hot period and in general they sort of get it," he added.

Harper said the vast majority of affected pak choi is still edible - even if "it seems to be quite tasty" for the beetles too.

Lucy Munns, a potato farmer in Cambridgeshire, said the hot weather will stunt the root vegetable's growth, leading to oddly shaped tubers that supermarkets and chip shops, which she supplies, wouldn't normally buy.

When the weather gets cooler after a hot period, instead of the main potato tuber growing "it tends to grow a little knobble on the end".

"Trying to find people that will accept potatoes like that is very difficult. So that ultimately means a lot of wastage for us," Munns added.

"It's criminal, to be honest, to be chucking that much food away."

Those "knobbly and misshapen potatoes" however are absolutely fine to eat, she said.

"The only difficulty is peeling them, but just cut the knobbly bit off and peel it separately."

Supermarkets including Sainsbury's, Tesco, Morrisons and Waitrose already have dedicated lines for wonky vegetables.

Calum Kelly, Waitrose's produce technical manager, said in demanding weather conditions "we relax size and shape guidelines for key veg to avoid waste and provide more income to our growers and farmers".

"Baking potatoes might be a little smaller than usual this harvest if the drought continues. All these veg still taste great, but like many of us in a heatwave, they might just look a little less than perfect."

Not every gap can be filled this way though. Andrew Opie, the director of food and sustainability at the British Retail Consortium, said supermarkets are also importing more food from abroad as UK supplies run short.

"Retailers face the dilemma of supporting British farmers, but also making sure that we, as customers, have what we expect to buy when we go in the shop," he said.

"It's going to be a challenging period right through into the autumn. We're hearing potentially it could affect things like cherries as well."

British summers are getting hotter and drier as the climate changes and heatwaves like this one are becoming more frequent.

That means a season like this one may become less of a one-off, and more of a preview of what British farming has to deal with regularly.

Many farmers will either have to accept more waste, invest in better irrigation and water storage systems, or find a way to sell more wonky produce to consumers.

Munns, the potato farmer, said more people should try buying imperfect veg if they see it in the supermarket aisle this year.

People should "be a bit less picky" about fresh produce, she said. "We've been too spoilt in the UK … In other less fortunate countries we wouldn't have a choice."