Gardeners urged to stop making this one mistake in the summer

With high temperatures sweeping across the UK in recent days and amber heat alerts issued on Wednesday for the West Midlands, East Midlands, South East, London, and the East of England, gardens across the UK are feeling the strain. According to the Met Office, the forecast for London and the South East on Sunday, August 16, predicts "a widely warm or very warm day with good sunny spells", along with intermittent cloud over parts of Kent and the Thames Valley, and light to gentle winds. Temperatures are expected to peak at 26C, according to the meteorological service.

Plants that have taken months or even years to grow can suffer or wither rapidly in prolonged heat without the right care. To help your garden thrive during the heatwave, Hamid Ali, horticulture expert at local services marketplace Airtasker, has revealed a lesser known gardening mistake that many people make during hot weather, and what to do instead.

While it may seem logical to keep your lawn neatly trimmed, mowing too low in a heatwave can actually stress the grass, leaving it vulnerable to scorching and dehydration.

Ali said: "Longer grass copes better with heat and retains moisture."

The Royal Horticultural Society (RHS) also recommends mowing conventional lawns once a week during the summer, but this this should be reduced to once every two weeks or less during droughts, when grass growth slows and extra cutting can do more harm than good.

If you're maintaining a flower-rich lawn, mowing every four to six weeks is sufficient, helping to preserve biodiversity and pollinator habitats. For long-grassed or informal lawns, the RHS recommends just one or two cuts per summer, ideally starting no earlier than June.

In terms of height, summer mowing should leave grass 13-25mm (½-1 inch) tall. Keeping it on the longer side during hot spells offers better ground cover and helps retain soil moisture, essential for lawn health during a heatwave.

Ali shared five other tips to help gardens not just survive, but thrive during the hotter months.

One of the most common mistakes people make is watering during the heat of the day, when most of the water evaporates before even reaching the roots.

The expert said: "Water early in the morning, ideally before 9 am when the ground is cooler and water can soak into the soil. If mornings aren't possible, late evening is the next best option, though cooler, damp conditions overnight can occasionally encourage slugs or mildew."

To try and save wilting plants, many gardeners also end up overwatering, which can lead to root rot and fungal diseases. Check if the top two inches of soil are dry before watering.

While pots and hanging baskets may need daily watering in hot weather, border plants often fare better with a deep soak a few times per week, the expert said.

Another common yet lesser known gardening mistake is using fertilising during peak heat. Feeding plants during heatwaves can stress them and burn their roots. It is best to use fertiliser when the temperatures have gone down.

Next, "don't forget to add mulch", Ali said. Exposed soil loses moisture rapidly in the heat. Applying mulch helps retain water, suppress weeds, and protect plant roots.

Ali advised: "Apply a layer of mulch, compost, bark chips, straw, or even grass clippings around the base of plants. This helps retain moisture, suppress weeds, and keep roots cool. For veg patches, try using straw or biodegradable mats between rows."

Lastly, make sure you also provide shade for vulenerable plants as even the most sun-loving ones can suffer in prolonged, intense heat. You can use a garden fleece, shade cloth, old be sheets, or a parasol to provide temporary cover.