In the run-up to a competition, professional athletes pay attention to the “one-percenters” – their diet, rest and time spent in the sun – small things, but together they make a big difference to performance. And so it is when growing a prize pumpkin.
If you sow the seed of a variety bred to be big, such as 'Atlantic Giant’, in the rich soil next to the compost heap, chances are you’ll end up with a 3st gourd. But watch those “one-percenters” and you can achieve a 20st prize-winner the size of Cinderella’s carriage.
The groundwork for a big pumpkin starts with a planting hole lavished with a minimum of one ton of well-rotted horse manure and the sourcing of “thoroughbred” seed from the internet. The best seed will cost from £5-£50 a pop but, if you start with the progeny of a former champion, you’re more likely to top the podium come harvest time.
Sow seed in a pot, as you would a courgette, in the warmth of the greenhouse and it’ll be up and ready to plant atop the settled manure-rich midden when there is little risk of frost.
Survival of the fittest
As the plant grows, remove all but one pumpkin fruit so all the energy gathered by the leaves is focused on the development of one super-fruit. If two are the same size, choose the one that’s roughly 3m (10ft) from the roots and growing from a main stem, not a side shoot.
On a large plant, culling all the pumpkins requires almost daily attention. The blowsy yellow female flowers – you can spot them by the marble-sized bulge at their base – are quick to set and can grow to tennis-ball size in a day.
I find the best tool for this job is a telescopic tree pruner – basically a pair of secateurs on a retractable 3m (10ft) pole – that allows me to pick off rival fruits from a distance without trampling the stems.
I must say, though, that cutting pumpkins before their prime does go against the grain. The upside is they make for far better eating – sliced, oiled, salted and baked with garlic – than when they’re big and as tasty as an overripe cucumber.
When your chosen pumpkin reaches the size of a football, set the fruit on a 4in bed of straw to protect the skin from stones in the soil and spread the pumpkin’s weight as it swells. Position so that the pumpkin reclines with the stalk and the stem to one side, then carefully bend the stem into a U shape to give the pumpkin as much growth space as possible. Moving a pumpkin is a delicate operation, particularly while it is in fast growth: the skin is so thin a fingernail will cause sap to bleed from the wound.
If this happens – or worse, a bird pecks your prize-winner – sprinkle with fungicidal sulphur dust to cauterise the cut and prevent infection from entering.
Watering is essential
Water is by far the most important influence on a potential prize-winner, accounting for a fluctuating 90 per cent of the weight. During dry weather, the leaves draw moisture out from the fruit to keep growing, which reduces the size of the pumpkin.
So keeping the roots hydrated is key. Do this with a hose or water butt set to drip alongside where the main stem meets the soil, or, better still, with soaker-hose laid in a spiral beneath the leaves and plumbed to the garden tap.
With the hose left to run for an hour every day – more if the weather is hot – the pumpkin will quickly start to plump up. During the most vigorous growth phase, achampion can bulk up 24lb aday. Yours might not gain weight this quickly, but the difference in growth from day to day will almost certainly be noticeable.
When watering, avoid wetting the foliage – this invariably leads to an attack of powdery mildew fungus that appears as a talc-like white coating on the leaves. Although the fungus won’t spread to the fruit, it curbs the capacity of affected leaves to photosynthesise, thereby reducing the growth of the pumpkin. Removing badly affected leaves and pruning side shoots that are crowded together and encroaching on your pumpkin will help to reduce this, as will feeding.
Use plant feed to succeed
Nitrogen-rich pelleted chicken manure is good for encouraging fast, leafy growth but when the days shorten, it’s time to switch to high-potash feeds to help fruit development.
I use liquid tomato fertiliser – a can every other day – as it is quickly taken up by the plant and has a balance of major nutrients that keeps the leaves looking lush, along with a weekly dose of dilute seaweed. Packed with micronutrients, the seaweed helps thicken up the leaf cuticles, reducing the risk of powdery mildew. It also gives tired pumpkin plants a second wind and encourages them back into growth.
Artificial feeding will only take your pumpkin so far. For a place on the podium, it needs to feed from the soil. Pumpkins root along the ground at the intersections or nodes where the stems and side shoots join. Cover with garden compost enriched with bone meal and mycorrhizae (e.g. Rootgrow).
The weather has a big effect on the size of your fruit. Shade the skin with ascreen during the day and keep it warm at night – it’s after dark that a pumpkin grows fastest. A polytunnel over the top is ideal, but if this is too high a price for pumpkin glory, second best are large, water-filled bottles placed around the fruit. These capture the warmth of the sun during the day and release it at night.
Finally, when you harvest your prize-winner and take it to be weighed, sever it from the plant with a 2ft “T” piece of stem and keep the ends in water like a cut flower, snipping them off moments before your contender is weighed.
Good luck! But fingers crossed it’ll be far too heavy to lift.
