A month-by-month guide to growing a monster pumpkin!
Start by purchasing giant pumpkin seeds from a seed supplier. Some good ones are ‘Atlantic Giant’, ‘Wallace’s Whoppers’ or ‘Paton Twins Giant’. These are all genetically huge pumpkin varieties and are perfect for growing yourself a monster!
Preparation
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In the winter before you begin this project, or at least 6 weeks before planting, you should aim to improve the soil in the area in which you plan to grow your pumpkin.
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You can do this by digging in ‘well-rotted’ manure or green waste (garden compost), or by adding soil improver. Pumpkins are hungry fruits and this will add the nutrients needed, as well as providing the best soil structure - increasing your chance of monster sucess.
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Our soils’ resources on digging clay and sandy soils can advise the best treatment for particular soil types.
See our ‘Pumpkin crop sheet’ for details on how to sow and grow your pumpkin plant. Below is additional month by month advice for growing a giant!
April
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Giant pumpkin seeds are larger than normal pumpkin seeds so before sowing, soak them for an hour or two in tepid water (20-30°C).
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Sow a couple of seeds pointy end down into a light, free-draining compost.
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Do not overwater! Pumpkins hate being cold and wet. The number one error for beginners is overwatering seeds before they germinate, which causes them to rot. Moisten the compost and don’t water it again until the surface has dried off.
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To encourage germination, keep the seeds somewhere warm and light (25-30°C is ideal). Your seedlings should start to appear within 3-7 days.
May
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Pumpkins grow VERY quickly. Transfer your seedlings into a bigger pot as soon as possible - you’ll be amazed at how the roots fill the new space.
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If all your seeds have germinated, this is the point to decide on the best one to keep (monster pumpkins take up a LOT of space!).
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Plant your seedlings outdoors from mid to late May, the more outdoor space you have the better.
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Keep plants warm, especially at night. If possible cover them with a cloche or horticultural fleece during cold spells.
June
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The aim now is to grow as many leaves as possible! Give your plants a high-nitrogen liquid feed which encourages growth of green leaves. These leaves will fuel the growth of the pumpkin once it starts to fruit and continue to feed it until they die off in the autumn.
July
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Yellow flowers will start to appear on your plant, look for a female one. Female flowers have a small pumpkin at their base and only have stigma. See our flower structure diagram to help you identify this flower.
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Choose a female flower on the main vine as far away from the stump of the plant as possible. This is where your pumpkin will form. You can let the bees pollinate the flowers for you, or you can do it yourself by removing some male flowers and using them as a paintbrush to dab the pollen onto the centre of newly-opened female flowers.
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Wait until more than one flower has been pollinated and then see which pumpkin gets off to the best start, before removing the rest. Your pumpkin will grow far bigger if you only have one fruit on the plant!
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Once your plant has been pollinated and fruit has started to develop behind the flowers, you can begin to give a high potassium feed, such as tomato food.
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Water regularly from now on - every day if you possibly can!
August
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If you are measuring your pumpkin be careful not to damage it as the skin is delicate and any scratches will cause a scar that could affect the overall size.
September
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Look after the plant and keep it healthy. Continue watering and feeding until the end of the month.
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Calculate and record your final estimated weight. If your pumpkin reaches 45kg, you’re doing really well. If you manage to grow anything bigger than 136kg, you’re on to something!
October
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Let the fruit mature and colour on the plant and remove before the first frost strikes. If storing, allow skins to harden in the sun.