How often should you mow a lawn?

The usual answer to “how often should you mow a lawn” is once a week, and it is right for the middle of the growing season and wrong at both ends of it. The interval a lawn actually wants is set by how fast the grass is growing, and in a UK climate that rate swings from almost nothing in January to enough growth in May to break a weekly schedule. A fixed interval is either scalping a lawn that has not grown or letting one get away from you in the fastest month of the year.

What sets the interval

Growth rate does. Grass growth runs on soil temperature and light: cool-season grass resumes growth when the soil holds above about 6C, the threshold Teagasc gives for meaningful growth, and accelerates as the soil keeps warming through spring. Cut the interval from the growth rate and the calendar takes care of itself.

The rule that turns growth rate into an interval is the one-third rule. The RHS mowing guide puts it as: mow regularly so you only need to remove a small amount each time, and never take off more than one third of the grass height. So the practical question is not “what day is it” but “how much has grown since last time”. When you can see more than a third of that height is gone, you are late.

A third condition sits under both, and it is the one that decides spring: the ground has to take a mower. Why calendar lawn advice is wrong covers the general problem, and when to cut grass after winter covers what to do about it in March.

How often through the year

When	How often	What the guidance says
Winter	Only in mild spells, at a high setting	Growth is minimal and the plant is rebuilding. Frost and waterlogged ground are the real stop signals: when to stop mowing in autumn
Growth just resumed	Once, light and high, then as growth allows	The first cut of the year is a tidy-up at about 40mm or the mower’s highest setting, not the cut that sets summer height
April	About weekly	Growth settles into a rhythm as the soil warms. Mow when there is growth to remove, inside the one-third rule
May to June	Weekly, sometimes more	Peak growth in most of the UK. This is the month a weekly schedule breaks: a fast May lawn can need cutting twice a week to stay inside the rule
Dry spells	Fortnightly or less, at a raised height	The RHS mowing guide drops to once a fortnight, or longer, during drought. Longer leaf shades the soil and slows moisture loss
Autumn	Keep going, higher, while growth lasts	Growth slows with soil temperature. The last cut of the year is late enough to matter and light enough to leave the lawn tidy

The rows are national guidance and the useful version is local. In a mild south-west winter grass may barely stop growing, while in north-east Scotland growth effectively stops for around two months. The same interval that is right for a lawn in Truro in February is wrong for one in Aberdeen in April.

Why a weekly schedule misjudges both directions

Mowing a lawn that has not grown is not maintenance. It removes leaf area the plant needs to rebuild roots and reserves after winter, at exactly the point when it has the least to spare. That is the argument for waiting for visible growth before the first cut, and the same logic applies all year: an interval should respond to the growth in front of you.

The other direction is simpler. A May lawn left for two weeks is a lawn you take down in violation of the one-third rule, or one you cut in two passes with a wait between them. Neither is what a schedule was supposed to prevent.

Mowing frequency and growth rate

Growth rate is a number, and it can be modelled. That is the part most mowing advice cannot give you: it tells you what to do in an average year, and your lawn is not living in one.

We model soil temperature at 6cm and growth potential on the PACE Turf framework for any UK or Ireland location, and the daily mow ratings in the forecast come out of that. A day rated well is a day the model says the grass is putting on growth worth cutting; a poor week in a cold spring is a week to leave the mower alone whatever the calendar says. The soil temperature page and the /method page show the inputs and what they assume.

How often to mow a new lawn

A lawn from seed is mowed on its own schedule. Stay off it until the new grass is around 5 to 6cm, then take a light cut at a high setting. Cutting new grass too early pulls seedlings and thins exactly the coverage you were waiting for. Overseeding: a timing guide and how long grass seed takes to germinate cover the first weeks in detail.

FAQ

How often should you mow a lawn in spring in the UK? Once growth is clear, about weekly from April, and sometimes more through May. In a cold spring the grass will not have read the calendar, and the interval follows the growth in front of you rather than the month on the page.

Is it bad to only mow every 2 weeks? In June and July it is often exactly right, and the RHS mowing guide drops to once a fortnight or longer in drought. In May it usually is not: that much growth at once tends to put you outside the one-third rule.

Should you mow the lawn in winter? Only in mild spells, and high. Growth is minimal, and frost or waterlogged ground does more damage than an uncut lawn. The last cut of the year and the first of the next one are when to stop mowing in autumn and when to cut grass after winter.

How do I know the lawn needs cutting? Look at the lawn rather than the date. Visible growth since the last cut, enough of it to stay inside the one-third rule, and a surface firm enough to take a mower. If you want the model’s opinion, the mow forecast rates each of the next ten days for your location.

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Check this week’s mow forecast. The daily ratings come from modelled growth potential for your location, which is the growth rate your interval should be answering to.