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Growing Giant Pumpkins – How to Grow Giant Pumpkins

How to Grow Giant Pumpkin – A Guide to Growing a Giant Pumpkin

How to Grow Giant PumpkinsI often get emails asking me for my “Giant Pumpkin Growing Tips” and “How to Grow Giant Pumpkins”. Well I won’t pretend to be an expert, I’ve never entered a giant pumpkin growing contest, but I have grown a couple of very large pumpkins in the past.

The world record for a giant pumpkin is, I believe, held by Joe Jutras from North Scituate, Rhode Island, USA. His monster weighed 1689 pounds (766 Kg) and was exhibited in Topsfield Fair, Massachusetts in September 2007. Awesome!

My more modest plan was to just give a big pumpkin to my nieces for Halloween but they grew even better than I expected.

There was one unexpected benefit to my giant pumpkins; some kids got onto the allotment site and tried to steal them. Fortunately they were too big for them to move! I never weighed them, but they were too big for me to lift without help. I touched on growing giant pumpkins in Vegetable Growing Month by Month but decided to expand on it a little here.

Giant Pumpkin Seeds

Like any vegetable, different varieties have been selected for different purposes. With pumpkins, the giant types have purely been selected for size, not flavour. So whilst these make great Halloween pumpkins they don’t always make a good pie. In part, this is due to the forcing in the cultivation

In the UK we have a few varieties of seed suitable for giant pumpkin growing, all available from the allotment shop: pumpkin seeds.

Dill’s Atlantic Giant Pumpkin Seeds

The Atlantic Giant Pumpkin is the variety I grew. It’s regularly produced monsters weighing over 600lbs. They claim it’s delicious, but I was just aiming for size

Pumpkin Hundredweight Seeds

Although this is a competition variety, it’s reported to have a good flavour. Perhaps a little outmoded now by the Atlantic Giant but good results can be had with it anyway.

Pumpkin Mammoth Seeds

Another good prospect for the giant pumpkin competition. Often produces fruits over 50 kg!

How to Grow Giant Pumpkins

Having obtained your seeds, you want to start them off quite early in April. Sow individually just under the surface into 3″ pots of multi-purpose compost and germinate indoors at 20 to 24 degrees. Pop the seed sideways into the compost to stop water sitting on it and causing rot. In a week or so, two weeks at most, the seed should have germinated.

Keep them warm in a greenhouse or coldframe. If you have late frosts then bring them into the house if need be to avoid checking the growth. Once the plant has started, growth will be fast. Move into larger pots if the roots start coming through the bottom of the plot.

Start hardening off by opening the frame in the day and when the risk of frosts is passed it is time to plant out, preferably under a cloche until the plant gets too large.

Preparing the Soil

Dig a hole about 2 feet square and deep, fill with good compost or mix well rotted manure into the soil. Add a few handfuls of general purpose fertiliser like fish, blood and bone or Growmore into the mix as well. The soil should end up slightly mounded.

Carefully plant out, teasing the roots if they’re circling in the pot.

Feeding Giant Pumpkins

OK, there’s lots of secret recipes and suggestions. I think most of them are made up to put people of the scent rather than anything else. Use a liquid feed like Miracle Grow fortnightly or liquid comfrey feed with some added sulphate of ammonia to increase the nitrogen content.

Cultivation of Giant Pumpkins

Allow plenty of space, for giants you need at least 8 feet between plants. The foliage feeds the fruit so you’re going to have a lot of it. Keep weed free and well watered in wet weather.

Once you have 3 fruits starting to form, remove any flowers that develop. We need to concentrate everything into one pumpkin. Once the three small pumpkins have started pick the best one and pinch off the other two.

If you’ve an old palette on site, put that under the small pumpkin whilst you still can or even some straw. You can use plastic sheet but it can encourage rotting if water puddles under the fruit. It’s really annoying to have a wonderful pumpkin and find the part on the ground has rotted. Some slug defence is a good idea as well.

Come the autumn, get a friend to help you lift your fruit!

Further Information on Giant Pumpkins

Giant Pumpkins Seed & Plants

Varieties that have won the RHS Award of Garden Merit will generally give consistent good results