Hi Italophile and Verdun,
Are you saying they should be given a really good soak not very often? How will I know when the roots have dried out?
thank you for your advice
Nick, are you growing in containers or in the ground? In the ground, a good deep soaking infrequently is better than frequent light waterings. The deep soakings encourage the roots deeper into the soil. Mine are outdoors and I only water more than once a week - very deeply - when the temps get into the high-30sC consistently.
In containers, you're more at the mercy of the size of the container and what the container's made of. Smaller ones will dry out quicker than bigger ones in warm weather and terra cotta dries out quicker than plastic because terra cotta "breathes".
One test for moisture is to stick a finger down into the mix as deeply as you can. With the temps the UK seems to be getting at the moment, I'd bet it would take a while for the roots to dry out completely.