Megalomaniac squashes? Here’s how to keep them in check

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.

Snipping back rampant leafy growth stops the plant’s plans for world domination
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.

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Get high-quality seed tailored to your plot for free

I am such a sucker for a bargain. I can’t resist rummaging through the “reduced to clear” bins of seeds that pop up in garden centres at this time of year. For the vast majority of species, these will still remain perfectly viable until next spring, giving you comparable results despite being up to half the price.

But what if you could get significantly higher-quality seed tailored specifically to the unique conditions of your plot for, essentially, zero cost? This is what you get if you try seed saving, and now is the perfect time to do it.

Given how simple it is to do, I am always surprised how few gardeners still save their seed. This was illustrated most starkly to me on a trip to Garden Organic’s headquarters at Ryton, Tyne and Wear, a few years ago. Their researchers had been comparing the performance of seeds from exotic and unusual vegetable plants – saved by immigrant communities on local allotments – with shop-bought offerings.

The results were astonishing. The unusual vegetable seeds produced significantly larger, healthier plants. All this from a stash of seeds kept in old coffee tins in a shed, despite these crops being more commonly found in countries from Jamaica to Vietnam. It turned out that after just a few years of collecting seeds from the best plants, local growers had not only saved themselves a few bob, but had bred superior varieties far better adapted to local conditions.

Seed saving is super simple, but here are three tips to boost your chances of success.

1) Only save seed from the very best plants: big yielders, ones with great taste or surprising disease resistance. As there is often a time lag between flowers and seed production, I tie a little piece of coloured string round my superstar performers to remind me which ones to gather come harvest time. I tend to save seed from all my plants, but seed savers should be aware that F1 hybrid forms will not “come true” (be typical of the parents) from saved seed. This is a disadvantage if you are expecting perfect uniformity, but to me the luck of the draw is half the fun.

2) Only harvest seed from fully ripe fruit. Ripeness is an essential indicator that the seed within is fully mature and capable of producing a new plant. Collect as many as you can, as some seeds may not maintain their viability until next spring, so hedging your bets makes sense.

3) The two overriding factors that determine how well your seeds keep are how dry they are and how cool they are kept. For home growers the simplest way is to dry them spread out between sheets of kitchen roll in a place with good air circulation, then store them in jam jars in the fridge with a couple more sheets of kitchen roll to absorb the moisture.