Self-confessed botany geek and TV gardening expert James Wong offers Hannah Stephenson some unusual tips and tricks on how to improve the flavour of your home-grown harvests

It’s all very well joining the ‘grow your own’ brigade – but what if your tomatoes don’t taste sweet, your beans are stringy and your chillis lack punch?

Before you head back to the vegetable racks at the supermarket, take some advice from TV gardening expert James Wong, who has just written RHS Grow For Flavour, a very interesting little book with tricks in it to make your crops much tastier.

This ebullient botanist and broadcaster tells me that if we water our crops too much they’ll lack flavour, that trying some alternative compost mixes may help us taste the difference and that not all crops taste better when they’ve just been freshly harvested.

The Kew-trained ‘plant geek’, who is currently ambassador for Fiskars and has a Homegrown Revolution range with Suttons Seeds, is clearly hoping to put the va va boom back into flavour.

“The things you aim to do for fruit may be the exact opposite of what you want to do for some vegetables. To get fruit to be more concentrated and sweeter, you need to reduce the water content of the plant, whereas with salad crops, you don’t want dried-out lettuce, you want it to be as full of water as possible.

“However, in general, the less you water and the less you fertilise and the sunnier the spot, the better your crops will taste.”

He refutes claims that heirloom varieties always taste better, and dispels myths that you should always defoliate leaves on tomato plants to help ripen their fruit and that liquid feed will lead the way to tasty crops.

He also challenges some traditional methods, advising us to pinch out the top of our tomato plants after they have set their first truss, to pick broad beans when they are tender and eat them like mangetout, and to use a dilute of molasses (which looks like thick, black syrup, available online as a horse supplement) to boost your crops grown in the ground.

This, along with advice on giving your lettuce seedlings a daily stroke to improve their establishment by up to 70%, as well as spritzing your tomato plants with aspirin solution, will make some traditionalists baulk, but he backs it up with a lot of scientific evidence to produce a book which seems to make sense.

Tomatoes happen to be a bugbear of mine. Every year, I grow them and every year they get late blight. Wong admits he was in the same boat but he’s finally cracked it.

“Firstly, there are some varieties that are much more tolerant to blight than others (he cites ‘Crimson Crush’ as an example), but another solution is one-truss training (pinching out the top of the plants after they have set their first truss of fruit, turning them into dwarf plants). This works because the fruit are produced so much earlier in the year so they are generally harvested before late blight occurs.

“Per plant, you end up with one instead of four trusses, but per square metre of beds you get exactly the same yield. The fruit from one-truss training are bigger, sweeter, contain more anti-oxidants and they are a better colour.

“As these dwarf plants can be packed in far closer together, their total yield in a given area stays the same.”

He has read thousands of scientific papers to support his theories as well as growing and trying the produce himself.

But he’d avoid growing vegetables which he feels are not worth the time, money or flavour difference compared with supermarket varieties.

“Some crops will taste measurably better if you grow them yourself, such as the right variety of tomato, strawberries and sweetcorn.

“Crops which would taste much the same as the supermarket, if not worse, include celery, most conventional onions and potatoes. If you are going for a regular King Edward, I don’t think anyone could tell the difference between a home-grown one and one bought from the supermarket.”

He says heirloom varieties aren’t necessarily superior.

“When I did my flavour trials, I was astounded by how few heirloom varieties made it to the top. Flavour is largely about genetics but if you have a modern variety bred specifically for flavour, it can out-compete or at least match any heirloom type.

“Take ‘Sungold’ tomatoes or ‘Mara de Bois’ strawberries, both famed for knock-out aroma. Their quirky looks and unique taste mean they are often referred to as ‘heritage’ types, but they were both actually bred as recently as the 1990s.

“Likewise, lovers of sweetcorn will know that modern ‘supersweet’ hybrids can be up to 10 times more sugary than old ‘favourites’. To say that heirlooms always taste better is nothing more than horticultural ageism.”

  • RHS Grow For Flavour by James Wong (Mitchell Beazley, £20, www.octopusbooks.co.uk)