I’m catching uo on my reading today, and have been flicking through the latest edition of Kew magazine (summer 2010). I was interested to see that scientists have been checking the very widely held gardening belief that it is important not to water in the heat of the day, because the sun’s fierce rays will be focused by the water drops and burn holes in plant leaves.
It turns out that it’s not true. Although the scientists were able to burn holes using the sun and spherical glass beads, they could not achieve the same effect with water droplets – partly because they are never spherical and partly because of the cooling effect of the water itself.
The only circumstances under which it was possible was where hairs on the plant’s leaves held the water drops above the leaf surface – helping them to remain more spherical and removing the cooling effect. But even this is unlikely to occur naturally because the drops don’t remain in place for long enough.
So that’s one less thing to worry about, although of course it is till better to avoid watering during the heat of the day as more water will evaporate and less will make it down to the plant roots where it is needed.
Have you come across a piece of gardening ‘wisdom’ that you later discovered to be false?