A prolonged heatwave can stress or kill garden plants quickly — particularly those in pots, newly planted specimens, or anything in exposed south-facing beds. Here’s how to give your garden the best chance.

Watering: the most important rules

Water in the morning

Watering in the cool of early morning (before 9am) is significantly more effective than evening watering, and far better than midday:

  • Less water is lost to evaporation
  • Foliage dries during the day (reducing fungal disease risk)
  • Plants can absorb water before the heat of the day stresses them

If you can’t water in the morning, early evening is the next best option.

Water deeply, not frequently

A shallow watering encourages shallow roots, making plants more vulnerable to drought. Instead, water deeply and less often — this encourages roots to grow downwards where the soil stays cooler and damper.

Water the roots, not the leaves

Wet foliage in sun can scorch. Direct water to the base of plants, not over the leaves.

Protecting plants

  • Mulch deeply: A 5–7cm layer of bark, compost or garden mulch around plants dramatically reduces moisture loss from the soil. It also keeps roots cooler.
  • Move pots into shade: Container plants are the most vulnerable as they have no thermal mass or deep roots. Move them into partial shade if possible.
  • Don’t fertilise during a heatwave: Feeding actively growing plants adds to their stress. Wait until conditions cool.
  • Let grass grow longer: If you’re still mowing, raise the blade. Longer grass shades its own roots and retains moisture better.

Saving your lawn

Most UK lawns go brown in a heatwave. The good news: this is almost always temporary. Grass is remarkably resilient and will recover with autumn rain. Brown does not mean dead.

If you’d rather keep it green:

  • Water deeply once or twice per week rather than lightly every day
  • Water early morning
  • Avoid walking on it during the hottest part of the day
  • Don’t cut it short

Using water wisely

During heatwaves, some areas may face hosepipe bans. Good practices:

  • Use a watering can rather than a hose for targeted, efficient watering
  • Collect grey water from showers and baths to use on non-edible plants
  • Set up a water butt to collect rain ahead of the next heatwave
  • Prioritise: edible crops, newly planted specimens, and anything in containers come first

Vegetables and fruit in hot weather

  • Water every day for tomatoes, courgettes, salad leaves and beans — they need consistent moisture
  • Tomatoes: erratic watering causes blossom end rot and split fruits. Keep it regular
  • Shade cloth over vulnerable crops (lettuce particularly) prevents bolting and scorch

Related: Current heatwave status · UK heatwave tips

Disclaimer: This article is for general information only. For medical advice about heat-related illness, consult the NHS website or your GP. For official heatwave warnings, visit the Met Office.