To grow the tastiest herbs, treat ’em mean

James Wong
Photograph: SA Joiner/Getty Images

When it comes to growing your own, it’s hard to find a better bang for your buck than with herbs. Not only are they gram-for-gram the most expensive crops in the fruit and veg aisle, but in most cases they are also hands down the easiest to grow. And, for a range of solid, scientific reasons, they will have measurably stronger flavour than almost anything you can buy in the supermarket. So here are a botanist’s simple tricks to grow herbs for truly unbuyable flavour.

To improve the flavour in herbs, you have to understand why the plants produce it in the first place

To know how to improve the levels of flavour compounds in herbs, you first have to understand why on earth the plants are spending time and energy producing these in the first place, and the answer may surprise you. They are chemical weapons.

Unlike animals, plants can’t run or hide from environmental threats, so they have developed a different evolutionary strategy in the form of chemical shielding. These compounds can cause their leaves to be so strong-tasting as to repel herbivores; possess powerful antimicrobial effects to fight off fungal and bacterial infections; and even act as a chemical shield to combat the damage from UV radiation. In fact, when it comes to much of plant-based medicine, it is this very defence system that we are hijacking and deploying in our own bodies. As humans, we evolved a universal appreciation for the flavour and scent of these compounds because, despite being often produced by plants as toxins, they can confer health benefits when small amounts are used.

Basil blush: it will thrive if planted out in your border. Photograph: Sergii Kumer/Alamy Stock Photo

The ingenious thing is that plants tend not to waste their metabolic energy producing large doses of these compounds unless they really need to. This means when herbs are grown under cosseted conditions to maximise yield, as done by growers for supermarkets, their concentration of flavour compounds tends to be lower than if they are grown under the slight stress of a suboptimal environment. In a home setting, this basically means being lazier, and watering and feeding far less. Happy days.

Another factor that determines the level of these compounds is UV intensity. The more solar radiation these plants are under, the more protective compounds they will make to shield their cells from damage. This means you should treat them to the warmest and sunniest spot your plot has to offer. As window glass can filter pretty much all UVB light, simply planting them on an outside windowsill rather than an inside one can make an astonishing flavour difference.

Finally, growing them in the ground – or at a pinch in a soil-based potting mix – rather than in pots, will provide them with a wider profile of minerals, many of which are essential building blocks for flavour compounds. This means you don’t have to splash out on fancy pots or high-nutrient potting compost. It really is a case of “treat them mean to keep them keen” if you are looking to concentrate herbs’ flavours.

Follow James on Twitter @Botanygeek