Watering can

When to water plants in hot weather

In the heatwave, make sure you're watering your plants at the right time of day

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.

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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.

Hot climate plants

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

  • Water plants a lot on a sunny day
  • Water plants in the soil in the garden in the morning or evening
  • Avoid watering in full sun
  • Put potted plants in shade, or water several times a day
  • Cold water from the tap is fine for plants
  • Pay most attention to shade plants and those from cooler or damper areas which will be less adapted to the weather we are experiencing
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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.”