World's priciest pumpkin progresses...

Two months on, an update on the progress of the world’s most expensive pumpkin seed

The plant so farAs I’m sure you are aware by now, I have been tasked with growing the world’s most expensive seed, which was planted outside in May. For the first few weeks the plant was protected by a cloche to keep the worst of the weather off and help it to establish. This was a good job too, as it turns out the greatest challenge the plant has faced is the unpredictable British weather. Throughout May we experienced chilly nights, this meant 6am starts and 9:30pm finishes to cover the plant with fleece overnight to prevent its growth being checked. Then we had one of the wettest Junes on record.

Roots growing at a buried leaf nodeAll this has meant that the pumpkin has not grown as quickly as I would have liked, and is about two weeks behind. I have still been investing huge amounts of time in making sure the plant has everything it needs for success. The last eight weeks have been spent training the main vine and all the secondary vines that come off it into the correct shape, along with removing all of the tertiary vines.


A helping hand

Time is also spent every second day on a task called vine burying. This involves piling soil over the bottom of every leaf node, which encourages the plant to send out roots at every node. This enables greater uptake of water and nutrients, and anchoring top-heavy plants to the ground. Now the plant has reached a large size there are often 40 nodes to bury every two days.

Alongside this I have a spraying and fertilising regime that involves treating the plant with Maxicrop, SB Plant Invigorator and my own special brew of compost tea (made from worm compost) once a week. Cold weather and low light levels have caused slow growth rates and some yellowing in the leaves; to combat this the plant has also been fed with low doses of dried blood (a fast-acting organic source of nitrogen) and Epsom salts (a fast-acting cure for magnesium deficiency caused by low temperatures).

Pollinated female flowers with male flowersPollinating by hand

It was a waiting game preparing for the plant to produce a female flower on the main vine (the location that will produce the heaviest pumpkins). The first female opened on the same day I had to go away for a few days! This meant a 5.30am start, pollinating the female flower by hand using male flowers taken from another of my giant pumpkin plants. It is important to pollinate by hand, not only to ensure good pollination (rather than risking the bees not doing their job), but also so that you can guarantee the parents of the seed inside the forming pumpkin. All plants in the cucurbit family are highly promiscuous and will pollinate each other easily, so I couldn’t risk the world’s most expensive pumpkin being pollinated by a bee that had just visited my courgette plants, rendering the seed taken from the pumpkin worthless.

Six day old pumpkinTwo becomes one

Hard work has paid off and I now have two female flowers on the plant that have been pollinated. The slowest growing will be culled and the other grown on and covered with towels to stop it ripening in the sun. Come along to RHS Garden Hyde Hall, say hello, and you might get a glimpse of a giant forming!

Follow Matthew's progress

Updates will be posted on the RHS Garden Hyde Hall Twitter using the hashtag #UKGiantPumpkin, and its Facebook pages.

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