When Does Grass Stop Growing? UK Temperature Guide

The Short Answer

UK lawns use cool-season grasses: ryegrass, fescue and bent. As a general guide, these grasses are slow or dormant in cold soil and become active as it warms through spring, with the fastest growth in mild, moist conditions. In hot, dry spells lawns commonly slow down or turn brown to conserve moisture — the RHS says a lawn that has stopped growing this way will green up again once rain returns.⁴ The RHS puts the minimum soil temperature for good grass-seed germination at 7°C.¹

The key insight most people miss: soil temperature usually matters more than air temperature for timing lawn jobs. Soil below the surface warms up more slowly than the air above it, so your lawn can still look dormant on a mild, sunny day. The RHS judges lawn jobs like sowing by soil temperature rather than the calendar.¹

Grass Growth Temperature Zones

As a general guide, UK grass growth roughly follows five stages through the year, from dormant to peak growth and back again. Where a primary source confirms a specific soil-temperature figure it is cited below; otherwise a stage is described by season and conditions instead. Check your own lawn with a soil thermometer for the most reliable reading.

COLDSOIL

Dormant: No Growth

Grass is alive but not visibly growing. Roots are inactive. Avoid mowing, feeding or walking on frozen grass. This is broadly a winter pattern, but the exact date varies by year and region — use the condition of the ground and grass, not a calendar date, as your guide. Seed sown now will simply wait until conditions improve.

WARMINGSOIL

Slow Growth: Season Starting

Grass begins to grow again, but slowly to start with. This period runs from late winter into spring, earlier in milder areas and later further north and at altitude. You may need a first, high-set mow. The RHS puts the minimum soil temperature for good grass-seed germination at 7°C — below that, expect patchy results.¹

7°+SOIL

Active Growth: Sowing Window Opens

Consistent growth resumes. Soil has now passed the RHS's stated 7°C mark — the same page notes that grass continues to grow in soil temperatures above 7°C, and this is also the minimum for good germination, so seed sown from this point should do better than seed sown when the soil was colder.¹ This is a reasonable point to start a regular spring routine: mowing, and a first feed if the lawn needs one.

PEAKGROWTH

Peak Growth: The Sweet Spot

Grass grows fastest in mild, moist conditions, broadly through spring and again in early autumn. This roughly matches the RHS's recommended lawn-sowing windows — mid-spring (March to April) and autumn (September to November) — when soil is warm enough and usually moist without summer heat or winter cold. Germination normally takes about seven to ten days in these conditions.² Use our grass seed calculator to get quantities right for this window.

HOTSPELLS

Heat Stress: Growth Slows

In hot, dry spells cool-season grasses commonly slow down and can turn brown as they conserve moisture rather than grow. The RHS says this is not usually a sign of a dead lawn: it will green up again once rain returns.⁴ Raise the mowing height, water deeply but infrequently if you choose to water, and avoid feeding during a heatwave. This mainly affects UK lawns during hot, dry spells rather than for a typical whole summer.

UK Grass Growth by Month

This is a general seasonal pattern for an ordinary UK lawn. The month-by-month soil-temperature figures that previously appeared here could not be verified against a primary source, so they have been removed; actual soil temperature varies by region, altitude, aspect and the weather in a given year. Use this as a general guide alongside your own soil thermometer.

Month	Growth Status	What to Do
January	Dormant	Leave the lawn alone. Plan spring work.
February	Dormant, stirring late in milder areas	Service mower. Order seed and feed.
March	Slow growth starting	First mow (high). Rake out moss. Check our frost date calculator.
April	Active growth	Sow seed, apply spring feed, start regular mowing.
May	Peak growth	Mow weekly. Feed if not done in April.
June	Peak growth	Mow weekly, more often if growth is strong. Water in dry spells.
July	Good growth, can slow in a heatwave	Raise mowing height in hot, dry spells. Do not feed during a heatwave.
August	Good growth, can slow in a heatwave	Late August: prepare for autumn sowing.
September	Growth picks up again	Good month to sow seed. Apply an autumn feed if the lawn is growing and not drought-stressed. Overseed bare patches.
October	Growth slowing	Mow less often, on a high setting. Overseed early in the month if you can. Aerate if compacted.
November	Minimal growth	Clear leaves. Avoid walking on wet or frosty grass.
December	Dormant	Leave the lawn alone. Enjoy Christmas.

What Temperature Do You Need to Sow Grass Seed?

The RHS puts the minimum soil temperature for good grass-seed germination at 7°C — below that, expect poor or patchy results, so it is worth waiting rather than sowing early and wasting seed.¹

The RHS recommends two windows for sowing a new lawn:

Spring: Roughly March to April. Good results, but spring-sown grass may not root in as quickly, since it tends to put more energy into flowering.²
Autumn: The RHS window runs September to November. Often the better choice, since seedlings have more time to establish before the first hard frosts — sow as early in this window as you can, while the soil is still warm.

In both windows the soil is normally warm enough and there is usually enough moisture, without the extremes of a UK summer or winter; germination normally takes about seven to ten days.²

Use a soil thermometer pushed a few centimetres into the ground for a more reliable reading than guessing from the air temperature or the calendar alone.

Use our grass seed calculator to get the exact quantity of seed for your lawn area, and check our guide on mixing grass seed with topsoil for the best overseeding results.

How to check soil temperature

A finger in the soil cannot tell you whether it is above or below 7°C, so do not rely on touch. Push a soil thermometer into the top few centimetres, take readings over a few days, and sow once they sit at or above 7°C, the RHS minimum for good germination.

When to Feed Your Lawn: Temperature Rules

Lawn feed is wasted on grass that is not actively growing. RHS guidance ties feed timing to the growing season and the product's own label, rather than a fixed calendar date.⁵

Feed Type	Typical UK Timing	Why
Spring feed (high nitrogen)	Late March to April	Grass is usually growing well by now and can use the nutrients. A further application can be tried after a couple of months if growth stays poor, but not beyond August.
Summer feed (balanced)	June to July	Sustains growth through the summer. Skip if a heatwave is forecast — feeding stressed, dry grass risks scorch.
Autumn feed (high potassium)	September to October	Strengthens roots for winter. Low nitrogen avoids soft growth that frost can damage.
Winter feed	Not recommended	Grass is dormant. Feed applied now is more likely to wash away than be used.

RHS guidance places a spring or summer feed in late March or April, while the grass is actively growing, with a further application possible after a couple of months if needed but not beyond August; an autumn boost follows on a product made for that purpose.⁵⁶ Always follow the rate and timing on your product's own label.

Use our lawn feed calculator to get the exact amount of feed for your lawn area, and our fertiliser calculator for granular fertiliser dosing.

Mowing Height Through the Year

The right mowing height and frequency change through the year as grass growth changes with the season. These are the RHS's own recommended cutting heights and mowing frequency.³

Lawn Type / Season	Mowing Height	Frequency
Ordinary lawn — spring & autumn	Up to 40mm	Weekly or fortnightly, depending on growth
Ordinary lawn — summer	13–25mm, raised higher in hot, dry spells	Weekly, dropping to fortnightly or less in drought
Fine lawn	6–13mm	More frequent than an ordinary lawn
Winter	High setting, if mowing at all	Not usually needed unless mild and still growing

The one-third rule: never remove more than one-third of the grass height in a single cut.³ Cutting too short shocks the plant and weakens the root system. If the grass has grown tall, bring it down gradually over two or three mows.

Recommended Products

Some links below are affiliate links. Affiliate links: GardenCalc may earn a commission if you buy through the partner links on this page, at no extra cost to you.

Soil Thermometer

Stainless steel probe, 0–100°C range. Push 5cm into soil for accurate readings. Essential for timing your sowing and feeding.

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Premium Lawn Seed (1kg)

Cool-season ryegrass and fescue mix for UK lawns. Sow once the soil is at least 7°C, the RHS minimum for good germination.

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Spring Lawn Feed (200m²)

High-nitrogen feed for spring, once the grass is growing actively. Greens up the lawn and promotes strong spring growth.

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Frequently Asked Questions

What temperature does grass start growing?

As a general guide, UK lawn grasses are dormant in cold soil and become active again as the soil warms in spring. The RHS judges lawn jobs by soil temperature rather than a fixed calendar date: it puts the minimum soil temperature for good grass-seed germination at 7°C, with weed seedlings appearing at roughly the same point as a rough field check. Separately, the RHS also notes that established grass itself keeps growing once soil is above that same 7°C mark, so overall growth typically stays slow until the soil clears it, then picks up as the soil keeps warming.

What is the ideal temperature for grass growth?

Cool-season grasses such as ryegrass, fescue and bent — the mixes used in most UK lawns — grow fastest in mild, moist conditions, broadly through spring and again in early autumn. RHS sowing advice for a new lawn recommends mid-spring (March to April) or autumn (September to November) for the same reason: soil is warm enough, there is usually enough moisture, and it is neither too cold nor too hot.

Does grass stop growing in hot weather?

Yes. In hot, dry weather UK lawns commonly slow down and can turn brown as the grass conserves moisture rather than putting energy into new growth. The RHS says this is not usually fatal: a lawn that has stopped growing and browned off in a hot, dry summer will green up again once rain returns. This mainly affects UK lawns during hot, dry spells rather than for the whole summer.

When does grass stop growing in winter?

Grass growth slows right down and mostly stops once the soil turns cold in late autumn and winter, broadly from November through to late winter. The RHS notes an exception, though: in spells of mild winter weather the grass can still be growing, which is why occasional mowing on a high setting may still be needed then. Otherwise, growth does not pick up properly again until the soil starts to warm the following spring. Exact timing varies with the UK's regional climate, so treat these as general dates rather than a fixed switch.

What soil temperature do I need to sow grass seed?

The RHS puts the minimum soil temperature for good grass-seed germination at 7°C; below that, expect poor or patchy results. The RHS recommends sowing a new lawn in mid-spring (March to April) or autumn (September to November), when the soil is warm enough and there is usually enough moisture without extremes of heat or cold; germination normally takes seven to ten days. A soil thermometer pushed a few centimetres into the ground is the most reliable way to check before you sow.

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Sources and checking notes

Guidance and cited figures were checked against the sources below on 28 September 2026. The month-by-month soil-temperature figures that used to appear on this page could not be verified against a primary source, so they were removed rather than presented as measured data; treat seasonal timing as a general guide and check your own lawn with a soil thermometer.

Royal Horticultural Society, Monthly gardening tips & advice: October – lawns.
Royal Horticultural Society, Starting a lawn from seed.
Royal Horticultural Society, Lawn mowing guide.
Royal Horticultural Society, Lawn care for drought conditions.
Royal Horticultural Society, Lawn care in spring and summer.
Royal Horticultural Society, Lawn care in autumn.

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