It’s time for the great British rake off!

The Big Allotment Challenge featuring Jim Buttress. Photo: PA Photo/Silver River/BBC
The Big Allotment Challenge featuring Jim Buttress. Photo: PA Photo/Silver River/BBC

Just as Simon Cowell knows his music, AND Bake Off judge Paul Hollywood knows his cakes, so award-winning gardening legend Jim Buttress knows his onions.

And his melons, aubergines, carrots, radish and runner beans.

The plain-speaking horticulturalist, former Royal gardener and current RHS Britain in Bloom judge is now also judge in BBC2’s new six-part series The Big Allotment Challenge, and he pulls no punches judging harvests produced by contestants on their made-for-TV allotments

Filmed in a Victorian walled garden on the Mapledurham Estate in Oxfordshire, nine pairs of keen gardeners have spent months planning, planting and nurturing. Given their own greenhouses, they were handed particular vegetables, fruit and flowers to grow, as well as facing a number of additional weekly challenges including flower arranging and chutney-making, judged by floral arrangement expert Jonathan Moseley and preserves specialist Thane Price.

The series, presented by Fern Britton, was filmed last year from early spring until late summer, when award-winning Buttress then judged the produce, from blemish-free radishes to perfect sweet peas.

So how harsh was he with this judging?

“I was once nicknamed Judge Dread but you don’t have to be hard, as long as you’re fair and consistent in what you do,” he insists. “You don’t have to hurt people but you can tell them, ‘This ain’t good enough’. Just be fair, be honest and give people advice as to why they didn’t win or they could have done better.”

Much of the advice he gives in this series is about the weather-related problems faced by competitors, because last spring was particularly cold.

“Last year, March and April were awful. Light levels were appalling, we had a lot of cold weather and many people were ‘caught cold’. Stuff was put out which wasn’t hardy enough. The one thing you’ll never beat is nature. Then Mr Pest and Mr Disease comes along. It happens to everybody. They had to find a way around that.

“The most difficult thing is the timing. People who grow stuff in the garden generally don’t have a deadline. Each week we set them a task, whether vegetables or flowers, and if they didn’t have them ready then they didn’t have an exhibit. Luckily they’d grown twice as much as they needed to guarantee they had something.”

The subsequent hot weather in summer helped the growth catch up, but then it required constant watering and some produce needed slowing down.

The second strand of the competition, which is growing flowers, also put up its own problems, Buttress says.

“Thrift was a menace last year with gladioli. They get the mottling vein. When the judge is looking at the exhibit, whatever it is, it’s the overall impression that matters. Is it free of blemish? That includes the root and the leaves and everything else. With the hot weather, stuff started to move much more quickly and required covering and protecting from the direct sun. They had the risk that sweet peas would flower too quickly.”

Some flowers weren’t successful simply because they need more time to establish, he reflects, a factor which also limited the types of vegetables they could grow for the series.

“Roses were a disaster. To get wonderful roses, you would have planted them two years ago. You couldn’t put a rose in, however good a plant it was in the first place, and expect exhibitor-sized flowers in the first year. The first year, the rose is digging his feet into the ground, getting used to where he is and then the second and third year the flowers will be better.

“That’s why we cut out rhubarb and asparagus from the show, because we always tell people not to pick those in the first year.”

Away from the cameras and looking at other people’s gardening, Buttress is busy with his own efforts - he will be building the Homebase - Time To Reflect garden with designer Adam Frost at the RHS Chelsea Flower Show, and he is also helping to produce a display in the pavilion to mark charity Perennial’s 175th anniversary.

Like all great gardeners, he admits he can’t wait to get stuck in.