Home-grown winter squash is one of those vegetables where there really can be a big flavour difference when compared with shop-bought specimens. Yet left to their own devices the plants can become real garden thugs, sprawling out metres in every direction. Unless you have rambling acres to spare, come early August they’ll have likely smothered any attempt at garden supports, swallowed up paths and be making a break for next door’s plot. So they’re not exactly the most practical of crops if you, like me, have only a modest suburban plot to play with. But things don’t have to be this way.
In many other countries, pruning is part of the standard advice on pumpkins and winter squash to keep their megalomaniac tendencies in check. Although barely ever recommended in UK gardening books, this deceptively simple trick can not only save you space, but will give you better quality fruit and an extra harvest of delicious leafy greens, all in exchange for a few minutes’ work. Let me explain…
Plant leaves function like living solar panels, converting the energy from solar radiation into sugars used to fuel their growth. This finite amount of sugar has to be split between the various plant tissues, so the more a plant is producing at the same time the further its resources are stretched. This basic metabolic principle means that snipping back rampant leafy growth on mature plants after fruit has set results in less energy being wasted on fuelling the plants’ plans for world domination, leaving more to dedicate to ripening fruit. The net result? According to trials, larger, sweeter, more nutrient-rich fruit with a higher ratio of tasty flesh to skin and seeds.
To get pruning, simply snip off the young growing tips with sharp secateurs. The exact length along the vine at which you start to do this ultimately depends on how much space you have and how vigorous the squash variety is, but standard advice varies from as little as 1m to as much as 3m after the last fruit has set, retaining about four fruit per plant.
But before you confine these trimmings to the compost bin, it is worth mentioning that these soft, young growing tips (picked about 10-15cm long) also lead a secret double life as a much-loved, green leafy vegetable all over the world. Providing two crops from a single plant, they are delicious used in all the ways you would spinach, but without collapsing into mush at the first sign of heat. With a satisfying crunch and fresh, mineral flavour, they are produced in quick succession from late July to October. It’s a handy incentive to get out there to do the pruning, too.
Email James at james.wong@observer.co.uk or follow him on Twitter @Botanygeek
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