Should I Water My Grass In A Heatwave?

I know you know. You know I know you know. But it bears repeating anyway: phwoar, it’s hot at the minute, isn’t it?

Parts of the UK have just seen their hottest May day on record, with parts of London seeing highs of 34.8°C during the bank holiday weekend.

That, gardeners know, can wreak havoc on a previously flourishing backyard. Some plants, like hydrangeas, fuchsias, and even roses, can be especially susceptible to the glaring heat.

But expert after expert has warned not to water one of the most ubiquitous plants, even after they’ve turned brown: grass.

It can be very worrying to see patches of your carefully-grown back garden turn brown and wilt in the heat. But luckily, the Royal Horticultural Society said, the plant is hardier than you might imagine.

During hot, dry weather, “lawns can turn brown and stop growing. Although this looks serious, the grass will green up once rain returns,” they explained.

And speaking to the BBC, Heather Taylor, also known as the “plant doctor”, also said we shouldn’t worry about the parched plant.

“If your grass is dry and parched, a bit of rain and it will be the first thing that will bounce back, don’t worry about it, it will be fine,” the expert said.

This isn’t to say yellowed or brown grass isn’t stressed – it is.

But, as Utah State University explained, “blades” of grass (the green part we see above ground) act as sacrificial lambs during tough periods, including drought.

These stop growing and become limp and discoloured in order to protect the “crown” of the plant, which lies just underneath the soil.

This is the node at which soil and root meet and is key to its survival: “As long as the crown remains alive, the grass has the capability to recover once temperature and moisture conditions improve”.

In fact, grass expert Richard Hull wrote for Turfgrass Trends, “The crown
literally is the turfgrass plant, or at least that which makes a turfgrass a perennial plant [a plant that grows back every year]”.

Often, he added, after periods of extreme drought or cold, it’s the only part of the plant that survives.

Unless that crown is damaged, your grass will likely be fine. And amidst increasingly common drought, some bodies like Scottish Water have called for gardeners to put the hosepipe down as water is “wasted” on grass.

Again, “Resist the temptation to water established lawns through the summer months, however brown they get, as the grass will send up new leaves once it rains,” the RHS warned.

New lawns may be the exception – use grey water or rainwater if they’re struggling.

They also advised against mowing your grass too short during hot weather, or doing so too often, because that can make the plant weaker and more susceptible to damage.

Stop mowing entirely if your grass has stopped growing. And if you can, keep your grass relatively long, “which should encourage deeper rooting”.