Amid creeping cross-festival gimmicks from Christmas eggs to Easter trees, the humble Halloween pumpkin has remained untouched by the marketing men.

That was until a chain of craft stores revealed it was to sell polystyrene pumpkins, a move branded as “total madness” by farmers who say it may prevent children knowing that pumpkins grow in the ground.

Craft supply chain Hobbycraft, with 85 stores across the UK, is selling polystyrene pumpkins for £1. Similar foam and plastic products can be found online from Amazon and Etsy.

While they may reduce mess in the kitchen and cut down on bent paring knives and orange shavings, environmentalists, customers and MPs are furious at another instance of “pointless plastic” which will soon go to landfill or to pollute the oceans.

“I think it’s totally unnecessary and total madness,” said Emily French, owner of Foxes Farm Produce in Colchester which sells thousands of pumpkins every autumn.