The summer heatwave has helped Asda's watermelon grower Joe Cottingham produce a bumper harvest at his farm in Kent. Here he blogs about how he’s done it…

We first started supplying our British-grown watermelons to Asda last year, when we harvested 1,000 of them after a successful trial growing 20 or 30 different varieties. We’ve learned a lot from our experience over the last couple of years, so this year thanks to the heatwave and exceptional weather we’ve had this summer we’ve grown 8,000 British watermelons – the most ever achieved on home soil by a retailer.

They're grown in polytunnels with insulated soil because they need protection in the early summer when you're still getting cold night-time temperatures. But this summer’s consistently sunny, hot weather has replicated conditions in warmer European climates where watermelons thrive, creating sweet, quality watermelons for Asda’s customers.

They weigh over 2kg on average and are showing sugar levels comparable with those of Spanish producers.

As well as the ripe and ready to eat red watermelons, we’ve also grown 800 golden yellow watermelons which are on sale at Asda. The taste is very similar to the standard watermelons, but the colour of the flesh is pretty striking and they smell a bit more perfumed.

It's always exciting when you bring new fresh produce to the market; that excitement never goes away! Produce is always changing and so are people's eating habits.

We’re always looking at ways in which we can adopt innovative growing techniques to try and become more self-sufficient here in the UK and provide customers with more choice when it comes to the British produce they see on shelf.

The main reaction we’ve been getting from people when they discover the watermelons were grown in Kent is one of surprise. We've had them in the office and everyone's been trying them. They'll ask where they're from and when we say our farm they say "really?!". People say they taste really good. As far as I'm aware no-one else in Britain is growing watermelons, so it’s great to be at the forefront of something new.

The British watermelons grown by Joe and his colleagues at Watts Farms are available for £2.50 each from September 14th at the following stores, subject to availability and while stocks last: Beckton, Belvedere, Bexley Heath, Brighton, Burgh Heath, Chadwell Heath, Charlton, Clapham Junction, Colchester, Crawley, Dagenham, Isle of Dogs, Leyton, Mitcham, Old Kent Road, Stamford Hill, Stepney Green, Sutton, Tunbridge Wells, Wallington and Walthamstow.