It is a common rule in gardening to avoid watering plants in the sunniest and hottest part of the day. It’s understandable that even seasoned gardeners might wonder, is watering plants in the sun bad? It turns out that the idea that midday watering can cause leaf scorch is a myth.
What is Leaf Scorch?
Leaf scorch is a physiological condition that results from poor environmental conditions. It is not an infectious disease. Leaf scorch looks like burned, brown, and dead areas of leaf tissue.
Does Watering Grass in the Sun Burn it?
This is an extremely persistent myth. There is no evidence that water on a leaf surface in the sun and heat will burn or scorch it. And yet, people notice a correlation, but it is coincidental or indirect.
The underlying cause of leaf scorch is inadequate moisture in the leaves. This can result from a host of poor conditions, particularly those that reduce root function, which limits uptake of water:
- Excess salt from ocean spray, road de-icing salt, fertilizers, pesticides, and herbicides
- Wind stress
- High temperatures
- Soil compaction
- Inadequate potassium
When people water plants during the day when they’re already damaged and the damage gets worse, they might associate it with the sun. But it is not sunlight on wet leaves that causes scorch.
Is it Okay to Water Plants in the Afternoon?
Watering plants in the heat of the day is not ideal, but not because the water and sun together will scorch the leaves. The main reason not to water when the sun is high in the sky and temperatures soar is because of evaporation. The heat from the sun evaporates a significant amount of the water you apply to the plants, which makes it an inefficient time to do it.
The ideal time to water is first thing in the morning before it’s too hot and the plants have time to dry out. Watering in the evening limits immediate evaporation, but it also limits evaporation period. The lingering water is conducive to fungal infections.
Often people see plants wilting in the hot, sunny weather in the middle of the day and avoid watering to prevent leaf scorch. But, once foliage shows signs of damage, delaying watering only makes it worse. If your plants are stressed, no matter what time of day, water them right away.
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Mary Ellen Ellis has been gardening for over 20 years. With degrees in Chemistry and Biology, Mary Ellen's specialties are flowers, native plants, and herbs.