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.
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
- 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
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.”
Record-breaking heatwave continues
It is worth knowing this guidance on watering in hot weather since this week, according to provisional reports from the Met Office, a new UK daily temperature record for spring and May has been broken, with 34.8°C being recorded at Kew Gardens on Monday 25th May 2026.
The figure is the highest daily maximum temperature recorded in meteorological spring, as well as the highest temperature in May. Records were also broken in other areas across the country from Heathrow to Brize Norton in Oxfordshire and Hawarden Airport in Wales.
According to the Met Office, breaking the 32.8°C May record is around three times more likely now in our current climate, with what was around a 1-in-100 year event now becoming around a 1-in-33 year event.
The Environment Agency has not yet, however, declared any droughts in the UK for 2026 yet. "Following an exceptionally wet autumn and winter, reservoir storage levels for England stand at 94.8%, which is slightly above average for this time of year, and all water companies are operating as normal," the agency reported on Gov.uk.
At the time of writing, there are no hosepipe bans in place and it is permitted to water your plants with a hose, sprinklers or a watering can by hand should that be necessary. However, gardeners are encouraged to save water and refrain from irrigating the garden where possible, and sticking to watering crops, pots and containers, as most plants in the ground will be able to withstand a short heatwave after a wet spring; and lawns will green up again quickly once temperatures return to more normal levels for the time of year.
For more tips on dry gardening, head to our piece on dry garden combinations and our list of drought tolerant plants.
