Wondering when to cut new grass from seed? If you’ve overseeded or reseeded your lawn this year, mowing at the right time is key to keeping it in tip-top condition.
Knowing when to mow new turf is one thing, but what about a lawn that’s just grown from freshly sown grass seed? Well, at this time of year, especially, timing is crucial – too early, and you’ll damage the young, tender shoots, but too late, and your lawn will find itself at the mercy of the first frosts.
To find out when to cut new grass that’s grown from seed, I gathered the wisdom of a few trusty lawn experts.
We’re halfway through October already, and before we know it, it’ll be time to stop cutting our grass for the winter.
Not yet, though – and if you sowed grass seed earlier in the autumn, there’s still a little time for the new grass to establish before cutting it for the first time (especially if you used fast-growing grass seed, like Miracle-Gro EverGreen Fast Grass Lawn Seed from Amazon.
‘Your newly-sown lawn should be ready for its first mow around six to eight weeks after you planted your seeds,’ says Chris McIlroy, lawn expert at The Grass People. ‘Check the temperature, as you want to avoid frost on a young, freshly-cut lawn.’
In fact, mowing during or shortly before frosty weather is one of the worst winter lawn care mistakes you can make.
Besides September and October, April and May are also considered ideal times to overseed a lawn. You’ll just need to wait the six- to eight-week window before you cut the new grass – and if you haven’t sown grass seed yet, you might not be able to squeeze in its first cut this year.
‘If you’ve just sown your grass in mid-October, it’s likely you won’t be mowing your new grass at all – not until spring 2026, anyway,’ says Chris Cooper, senior product marketing manager from the lawn experts behind Hayter petrol and battery lawn mowers.
I was curious about how long grass should be before it can be mowed for the first time, too.
‘The key thing is to wait until it’s strong enough to handle its first cut,’ says Cheryl Harper, managing director of Greensleeves. ‘As a rule of thumb, you should hold off mowing until the new grass has reached around 7-8cm (about 3 inches) in height. That gives the young shoots time to develop a good root system and gain a bit of strength.’
According to Cheryl, the height of the grass is actually a better indicator than the calendar – so keep an eye on the length of the blades this month, as the wetter, milder weather might speed up growth and shorten the wait time a little.
Just try not to mow too early. ‘This can be tempting, especially as the autumnal weather firmly sets in and you want to mow before it gets too cold, but you need to ensure your grass is well-established to limit damage to the roots and avoid patchy growth,’ explains Chris from The Grass People.
It’s also best to avoid cutting your grass too short (another ultra-common lawn care mistake) during its first mow.
‘When you do take the mower out for the first time, make sure the blades are nice and sharp, and just trim the top third of the grass,’ advises Cheryl. ‘That gentle first cut helps the grass thicken up without putting it under stress.’
A lot of the best lawnmowers on the market have an easily adjustable cutting height mechanism, like the Gtech CLM50 Cordless Lawnmower from Amazon, which I tested earlier in the year (and loved!).
So, six to eight weeks from sowing is a good guideline, but make sure new grass from seed is long enough before you cut it for the first time. Get your hands on a good lawn mower to make life easier, or make sure your lawn mower blades are properly sharpened before you get started.
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