Lawns
Watering Your Lawn at the Wrong Time of Day Wastes Most of the Water You Use
Early morning is the best time to water a lawn, with early evening a fair second. The bigger question is whether an established lawn needs water at all.
By the Aspen Rose team6 min read
Get the hour right and you still have not answered the bigger question: most lawns in London and Hertfordshire don't need watering at all. The RHS is direct about this: leave an established lawn alone through a dry summer and the grass regrows once rain returns. Timing only earns its place for new turf and seed, repaired patches, and any lawn you have deliberately decided to keep green.
Why is early morning the best time to water a lawn?
Early morning wins for one reason: less water evaporates before the lawn gets the chance to use it. That is the RHS's own advice for watering in general, and the logic holds just as well for grass.
There are two further reasons, one for the lawn and one for the mains.
- The grass dries out sooner. Wet foliage that stays damp overnight is easier for pests and fungal disease to take hold on. Water in the morning and the blades have all day to dry.
- You avoid the evening rush. The RHS notes that household water use peaks in the early evening, so watering earlier in the day helps spread the demand.
Is evening watering a mistake?
Not a mistake, but not the first choice either. The RHS says the downside is leaves left wet overnight, which can invite pests and fungal disease. If you can only water after work, go early in the evening rather than late, so the lawn still has daylight hours to dry before dark.
For pots and baskets the RHS names early morning or early evening as equally sound, so the evening is a real option when the morning is not.
Does watering in the midday sun scorch grass?
The scorching story is mostly a myth, but midday is still a poor time to water. The RHS does say droplets can focus sunlight and burn leaves in bright sun. It adds that hairy leaves are more at risk than smooth ones. Research reported in HortMagazine, led by Dr Gabor Horvath at Eötvös University in Hungary, found that droplets on smooth leaves such as maple did not cause burns, while droplets held on hairy leaves such as ferns could. Neither the RHS page nor the HortMagazine report names lawn grass as a plant at risk.
Scorching was never the real argument against midday watering. Waste is. The RHS says much of the water evaporates before it reaches the roots in the hottest part of the day, so a midday session mostly waters the air.
What changes for new turf and newly sown lawns?
New lawns are the one case where watering is not optional, and the usual timing advice still applies. Turf Online, a turf supplier, recommends early morning or late evening, when it is cooler and less water is lost. It says to soak the top 10cm of soil and keep it damp until the turf has rooted, which it puts at two to four weeks.
The same supplier warns that in hot weather unwatered turf can die within 48 to 72 hours. If new turf is visibly drying out, water it now and do not wait for the ideal hour.
Which time suits which lawn?
| Situation | Best time | Why |
|---|---|---|
| Established lawn in a dry summer | Usually no watering | The RHS says it regrows after rain |
| New turf or seed | Early morning, or late evening | Cooler, less evaporation; never let it dry out |
| Repairing a bare patch | Early morning, gently with a fine rose | The RHS says to keep newly seeded lawns from drying out on the surface, using a can with a rose or a hose with a gentle spray |
| Dry patch (water-repellent soil) | Early morning, a little each day for a few days | The RHS advises spiking first, then light daily watering |
| A small lawn you want to keep green | Early morning, with stored rainwater or grey water | The RHS says to use mains water only as a last resort |
What about a heatwave or a hosepipe ban?
In a heatwave the case for early watering gets stronger. The RHS container advice says plants use and lose more water in warm, windy weather, and watering at cooler times of day cuts evaporation. The same reasoning is sensible for a lawn you have chosen to water.
During a temporary use ban, hosepipes and sprinklers cannot be used on a lawn at all. Thames Water's page says watering cans and stored rainwater are still allowed. Our article on watering your garden during a hosepipe ban sets out what is and is not permitted, and how often to water a lawn covers how much.
If you would like a second opinion on your lawn, we offer a free, no-obligation visit through our garden maintenance service.
Sources
- RHS: Watering plants wisely
- RHS: Use less water in the garden
- RHS: Lawn care for drought conditions
- RHS: Lawn care in spring and summer
- RHS: Lawns, dead patches and fixes
- RHS: Weather damage
- RHS: How to water containers
- RHS: Garden watering methods
- RHS: Lawns, dry patch problems and fixes
- Turf Online: How long do I need to water my turf after it is installed?
- HortMagazine: Q&A, watering in the sun
- Thames Water: Temporary hosepipe ban
This reflects what tends to work on lawns in London and Hertfordshire's climate and soils, not a guarantee for yours. Every lawn is different, so treat this as a starting point. Get in touch if you'd like us to take a proper look at what's actually going on in yours.
Lawn watering time questions
Is a watering can better than a sprinkler for a lawn?
For most garden watering the RHS rates a watering can as the most efficient tool, and sprinklers as among the least, because a lot of water is lost to evaporation and runoff. Its garden watering methods page accepts a sprinkler only in very limited cases, such as a newly sown or turfed lawn, and its watering guide suggests a can with a rose or a hose with a gentle spray for new lawns.
Can I use water from a butt or washing-up water on a lawn?
Yes. The RHS prefers stored rainwater and grey water to mains water for new grass. Grey water may contain soap or detergent, so use it within about a day, apply it with a watering can, and keep it off edible crops.
Should I water in a lawn feed?
Follow the packet rate. The RHS says to spread a spring or summer feed evenly, ideally in cool, moist conditions when rain is expected, or to water it in lightly afterwards. It lists a fertiliser overdose among the causes of dead patches in a lawn, so do not apply more than the packet says.
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