There Is A Myth That You Should Not Water Plants During Strong Sunshine Because The Water Droplets Magnifying The Sun & Will Burn Leaves.
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Common sense can quickly point out the folly of this myth. Which makes me wonder why people believe that You Should Not Water Plants During Strong Sunshine. Here’s the common sense bit. It frequently rains, even when the sun is out. But we don’t see widespread damage to leaves. It is rare and can be explained in other ways. Water droplets also evaporate quickly when it is sunny. So they aren’t going to be there long enough o do much damage. Now try this experiment. Spray some water drops on the back of your hand (or other sensitive skin!) and hold your hand out in the sun. Do you get burnt but the magnified water!
Lastly look at a water droplet. It isn’t lens shaped. It is a bit flattened and not very good at magnifying light or heat.
Why watering your plants at noon won’t damage their leaves
Rather than listen to me, I’ve included a New Scientist video compered by James Wong. Listen to what he says. And if you are time challenged just read the short summary of his comments in the section below.
🌱 Summary
💡 Myth Busting: Many believe watering plants in full sun causes leaf burn due to water droplets acting as magnifying lenses.
🔬 Scientific Investigation: Scientists used glass beads to mimic water droplets and confirmed they can focus sunlight to burn leaves. BUT ……
🌿 Real-World Conditions: However, actual water droplets are flat, not spherical beads, preventing this effect.
🌞 Evaporation Factor: On hot, sunny days, water evaporates before it could concentrate sunlight enough to cause damage.
👨🔬 Expert Opinion: Observational evidence shows no signs of burned leaves after midday watering.
🚰 Best Practice: Water plants whenever they need it, especially on hot days.
📊 Insights Based on Numbers
Thousands of tiny lenses would be needed to cause noticeable damage, but no such damage has been observed.
Water evaporates too quickly in strong sunlight to allow magnification-based burns.
Personal Observations Based On Market Garden Watering
On my market garden we grew 10,000 tomatoes a year under glass (ie in greenhouses). Every day I jetted them with water to pollinate them (ignore those that tell you this causes blight .. it doesn’t. In two decades I never had any blight.
The water droplets on the leaves did no harm whatsoever.
Now let’s consider plants with more fragile leaves. Crops such as lettuce, celery etc. We used overhead irrigation on these crops. Small droplets of water, just like rain. We did it at all hours, especially when sunny. Despite growing half a million lettuce a year I never once had burnt leaves.
The one way to ensure you DO burn leaves is to leave a hosepipe in the sun and then jet that over plants. The water in the hosepipe gets extremely hot and will burn your hands. It does even more damage to plants. But this is due to it being very hot water, not due to the sun.
Conclusion: Should You Water Plants During Strong Sunshine
The claims that damage is caused when sunlight is magnified by water droplets is a myth. There is no reason not to Water Plants During Strong Sunshine. The science shows this to be the case and so does common sense and experience.
