The pumpkin was grown by RHS Garden Hyde Hall’s edibles expert Matthew Oliver at the garden, near Chelmsford, Essex, and set a new UK record when it was weighed at the annual autumn pumpkin festival in Royal Victoria Park, Southampton on Saturday.
Triple the number of visitors came to the garden on Sunday compared to an ordinary weekend, after the 4.5m-circumference monster fruit appeared on BBC Breakfast. And it is set for a starring role in the garden’s Halloween ‘Garden Graveyard’ display, from 22 October, alongside its three back-up giant pumpkins and 60 other varieties of winter squash and gourds.
The fruit had a good chance of achieving greatness, after it was grown from a £1,250 seed from the then world’s biggest, 1,054kg, pumpkin, bought at auction by Thompson and Morgan. But it took the loving care of Oliver to reach its potential.
In fact he was so dedicated to his task he has not had a holiday between when it was sown in mid-April until it was harvested on Friday.
"It took lots of time. There are no massive secrets of growing them. It’s putting in the hours," he said. "I was down there every day for 149 days, even if it’s just to go and check on it."
He said he was definitely having a year off next year but said he might try again in 2018.
"I really enjoyed it, it’s been fantastic. Pumpkins are really good fun plants to grow. I can understand why it gets addictive, there’s nothing else in the world quite like it. It will grow 30 to 40lb a day, that can’t be matched by any other plant."
After starting with the right seed, Oliver prepared his bed and as the pumpkin grew, trained one vine down the centre and trained the smaller vines to lie along the ground at right angles, in what is called the Christmas tree pattern. Other main vines are cut off. In June, Oliver started ‘vine burying’, or putting soil on top of vine leaves to encourage them to sprout roots and take up more nutrients from the soil. Up to three can form on the base of each leaf.
"This anchors them to the ground and stops them blowing away. It’s very windy here. I spent hours and hours doing that in June, at one stage I was probably burying 40 leaves a week."
He added: "You need to pollinate the main female flower on the main line, 10 to 15ft out from the roots. You would normally pollinate two or three flowers to see what goes best but because of the cold weather in May and June we only had one."
In early July, disaster was averted after the main stump split. Fearing it would rot, Oliver took the novel approach of running a tabletop fan into the garden and training it on the root 24 hours a day, rigging up a waterproof shade to protect the fan.
"It took a long time to get it to heal over. If we hadn’t done that we probably would have lost it," he said. "I didn’t want to take any chances."
"The fruit also spent its days under cover so that it would not ripen too quickly and split in the sun."
Oliver also used dried blood fertiliser early on, sprayed with Epsom salts and Maxi Crop tomato feed once a week, used a root drench twice a week and also used SB Plant Invigorator which has been shown to have control over powdery mildew, "public enemy number one when it comes to growing pumpkins", he said.
It was also important to water the plant for an hour each morning using the same amount of water each time, as inconsistent watering can also lead to splitting.
"It has to be 100 per cent perfect. The dry summer really worked in our favour because it gave me more control over watering."
Ian and Stuart Paton of Pinetops Nurseries in Lymington took the UK record for a giant pumpkin for the seventh time with a fruit that has a circumference of nearly eight metres and weighs in at 1021kg. A pumpkin weighing 1.190kg on Sunday at the Giant Pumpkin European Championship in Germany set a new world record.