By Daisy Bowie-Sell

Published: Tuesday, 21 June 2022 at 12:00 am


High noon, the cool of the morning or the shade of the evening; there are many theories about the best time of day to water your plants. And in a heatwave it’ll pay to get it right.

According to Stuart Thompson, senior lecturer in plant biochemistry at the University of Westminster, plants go through their own weight in water on a sunny day. He explains that plants that are not in pots will benefit most from being watered morning or evening, when droplets have time to soak down into the soil.

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The common belief that water drops act like magnifying glasses and scorch leaves if they are wet is incorrect, according to Thompson, with the exception of leaves with hairs which could hold drops far enough away from the leaf for sun rays to be focused on the leaf surface.  General advice is to avoid watering in full sun, however, because water will evaporate before it can properly wet the soil.

Potted plants will use up water very quickly, so moving them into shade would be advisable, or watering several times a day may be necessary.

Top tips for watering in hot weather

Thompson added: “Plants have systems to reduce their water loss, which are very effective in species from arid environments where light is intense, such as succulents and yuccas, and so these will need less care.”