Green-fingered Phillip Vowles, 65, was stunned when the veg weighed 118lb in just five weeks.
Phillip, a retired gardener and farm worker, said: “It’s very unusual for one to grow so fast.
“The world marrow record is around 150lb so it could get close at this rate.” Phillip’s 11-month-old granddaughter Sophia has been having fun clambering over the 38in long vegetable at his garden in Llanharry, South Wales.
Phillip, who once grew a record-breaking 18.5lb cucumber, said: “Friends and neighbours get a big thrill out of me growing these things and the grandchildren like to see how big they get.
“This is the biggest marrow I’ve grown. My son had to help me lift it.”