When is the best time to water grass? We ask the experts

young woman water lawn with hosepipe
watWatering should be done in the mornings. File picture (Image credit: Getty)

Choosing the best time to water grass is key to having a lush and verdant lawn, particularly during the unpredictable British summer.

While it may seem like a relatively simple chore, factors such as the time of day, amount of water used, and whether the grass has been cut can affect how your lawn looks.

And if you’re looking to conserve how much water you use, check out our guide on the best water butts.

When is the best time to water grass?

Cheryl Harper, Managing Director at Greensleeves Lawn Care, says it is best to try to water as early in the day as you can.

She adds: “This gives the water a chance to soak into the turf before the day gets too warm and it evaporates.”

The RHS states that watering should be done in the mornings, as this is when the sun comes up and plants will start to use water. The foliage and soil surface is also likely to stay drier for longer than evening watering, discouraging slugs, snails and mildew diseases.

Plants start to transpire in sunlight, drawing water from the soil, through their roots, up their stems and out through tiny pores on their leaves called stomata.

Some people opt to water the lawn at night, but most gardeners agree morning is better where possible. “If you have to water it in the evening, don’t leave it too late, as watering at night can promote ideal conditions for fungal growth,” Cheryl adds.

That said, in hot weather, watering the lawn at night is unlikely to cause mildew and fungal growth so this does depend on weather conditions. Other gardeners also prefer not to water the lawn at all as this can affect the condition of your soil.

How much water does grass need?

It’s difficult to know how long to spend watering a lawn, but a general rule of lawn care is that a lawn needs around an inch to an inch and a half of water once per week for optimal growth. It’s best to water once or twice a week – deep and infrequent is better than often and shallow.

However, be flexible. In summer you will likely need more water for your lawn. Check the level of moisture in the ground. If the ground is hard or starts to lose some of its lush green colour, then it needs more water.

You may also be wondering how much water does a garden sprinkler use per hour when thinking about lawn care.

Can you damage grass if you use too much water or water it at the wrong time?

If you apply too much water to your lawn you can cause it to get saturated or soggy.

Cheryl adds: “Turf flooded by water can’t breathe and will eventually start to destroy your lawn. Not just on the surface but the roots as well.

“If it feels spongey underfoot you’ve probably overwatered, it. Overwatered grass can be ideal conditions for weeds and fungi which can quickly cause havoc on your lawn.”

When you water at night, if the weather isn't hot, the water can sit on the grass instead of evaporating. The soil may become water-logged instead of draining properly with help from the sun. This is detrimental to your lawn because it leads to mould and fungal growth.

Should you water grass after cutting?

“Does watering grass in the sun burn it?" is a common question asked by gardeners, but you should only water your lawn if it needs it. Set your lawnmower to a higher cutting height during summer, as longer grass provides shade to the soil, reducing water evaporation and promoting deeper root growth.

“Think little and often during the summer,” Cheryl says. “If your grass is too short, it can lead to scorched leaves and water evaporating quickly, ultimately damaging your grass.

“Lawns are full of weed seeds just waiting for the right conditions to germinate. Long grass is one of the best weed control methods you can have.”

Sam Webb

Sam is based in Coventry and has been a news reporter for nearly 20 years. His work has featured in the Mirror, The Sun, MailOnline, the Independent, and news outlets throughout the world.  As a copywriter, he has written for clients as diverse as Saint-Gobain, Michelin, Halfords Autocentre, Great British Heating, and Irwin Industrial Tools. During the pandemic, he converted a van into a mini-camper and is currently planning to convert his shed into an office and Star Wars shrine.