Can you water in the midday sun?

The thinking behind this is that the water droplets on the foliage amplify the sun’s rays – much like a magnifying glass – causing the leaves to burn. It turns out that this widespread belief is not true! To be sure, a few years ago, a group of scientists in Europe conducted a bunch of experiments that disproved the age-old theory. They started by examining the effects of water droplets on smooth leaves in the midday sun. While they did observe a focus of light on the leaf below, any heat that was created was transferred back to the water droplet, and as the water warmed up, it evaporated and
vanished, leaving no burn marks. Hairy leaves were also observed. The hairs kept the water off the foliage, which meant it couldn’t absorb the heat from the leaf, but the tiny droplets still evaporated quickly or were shaken off in the wind.

So, when you’re looking out at your patch on a stinking hot day and you see your plants crying out for a drink… don’t let them suffer! Instead, know that you can give them a good midday soaking without the fear of causing foliage damage. Don’t make a habit of it, though. Midday is when the evaporation rate is at its highest, so a lot of moisture will be lost before it reaches the roots. It’s a terribly inefficient use of water. When conditions are hot, water your beds in the late afternoon or very early morning. This allows enough time for the moisture to soak deep into the soil, where it can be taken up by the roots before the vaporising effect of the hot sun kicks in.

Photo by iStock