I am fascinated by old gardening books. The dusty pages, the tannic smell, the weird and wonderful language, but most of all the quirky tips and advice. Yet as a botanist I can’t help but read them with equal parts captivation and scepticism. Many of the most popular and enduring traditional practices have been disproven over the years, while in some cases science has found measurable benefits. Nowhere is this more apparent than fruit thinning – a simple trick that can dramatically transform the quality of your harvest with a few snips of the secateurs.
Now is the perfect time to be fruit thinning, although I still find some elements of the concept vague. For example, what do horticulturists mean by fruit “quality”? For years I have read about snipping off the immature fruit in late June to improve this mystical attribute, but no books ever explain what this actually means. The laws of basic biology state that lopping off a large proportion of the fruitlets that have just begun to swell can make each of the remaining ones significantly larger and therefore, by extension, potentially more evenly formed. Less, it has been proven, is more – the energies of the plant aren’t split between quite as many investments.
But this got me thinking: “What is so special about bigger fruit?” I’ve always assumed the smaller, runtier fruit has proportionally more surface area and therefore a more nutrient- and fibre-rich skin. Also, isn’t one of the big pluses of growing your own that flavour and nutrition get to trump the bland, cosmetic perfection of supermarket produce?
Keen to investigate my assumptions about whether thinning was a waste of time I looked to see if anyone has done a trial on this. It turns out there are dozens from all over the world and, funnily enough, they all prove me wrong. Evidence consistently shows that reducing the number of fruit on each plant not only improves size but dramatically raises the sugar content of the fruit, and even the phytonutrients (chemicals that help protect plants from germs, fungi, bugs and other threats).
And so all you really need to do at home is wait until mid to late June when a phenomenon called the “June drop” occurs. Trees will spontaneously shed some of their fruit in an effort to save their energies and as soon as this happens it’s just a case of taking the tree’s work a bit further, snipping off the young fruitlets with a clean, sharp pair of secateurs. The old adage to “thin, thin some more, thin till you want to cry, and then thin more” is a surprisingly apt description of what it feels like. In fact, it really is hard to thin too much. I’d recommend a good 20 minutes of snipping for larger, juicier, sweeter and more nutritious fruits.
Email James at james.wong@observer.co.uk or follow him on Twitter @Botanygeek
