At What Temperature Does Grass Stop Growing in the UK?

Max Letek

Garden-Review

If you’re wondering why your lawn seems to suddenly stop growing as autumn sets in—or why it’s barely budging in early spring—you’re not alone. Grass growth is highly influenced by temperature, especially in the UK’s cool, temperate climate. Understanding the temperature thresholds for grass growth is essential whether you’re a homeowner aiming for the perfect lawn or an allotment gardener keeping turf tidy between beds.

In this article, we’ll cover:

At What Temperature Does Grass Stop Growing?

In the UK, grass typically stops growing when soil temperatures fall below 5°C (41°F). While this might vary slightly depending on your location and lawn type, 5°C is a good general benchmark. Once temperatures dip below this, grass enters a dormant phase where it essentially “shuts down” to conserve energy. You’ll notice that growth slows dramatically—or stops altogether—from around late October through February.

When Does Grass Start Growing Again?

Grass starts to grow again when soil temperatures consistently reach 5°C or above, usually in early to mid-March, depending on your location and weather patterns. However, growth really kicks into gear at around 10°C to 15°C, which is more common by April. This is when your lawn begins to green up and fill out after its winter dormancy.

Quick Reference:

Dormant below: 5°C
Active growth begins: 5–7°C
Rapid growth: 10–15°C

When Is the Best Time to Sow Grass Seed in the UK?

Timing is everything when sowing grass seed. In the UK, the ideal times to sow are:

✔️ Spring: Mid-March to May

Soil warms up enough to support germination
Less risk of drought than summer
Good rainfall levels aid seed establishment

✔️ Autumn: Late August to September

Warm soil and cooler air encourage quick germination
Fewer weeds compete for space
Less foot traffic gives new grass a chance to settle

Avoid sowing in summer, when high temperatures and dry spells can hinder germination, or winter, when soil is too cold.

When Should You Cut Your Lawn?

First Cut of the Year:

Usually between mid-March and early April, depending on your region. Make sure the grass is dry and soil is firm. Set your mower blade high—don’t scalp it!

Regular Cutting Season:

From April through October, mow weekly or fortnightly depending on growth. During peak growing months (May to July), you may need to mow more frequently.

Final Cut of the Year:

Typically in late October or early November, before temperatures fall consistently below 5°C. Again, raise the mower blade slightly for this last trim.

Does Grass Grow in a Heat Wave?

During a UK heatwave—typically with temperatures above 25°C for several consecutive days—grass growth can slow down or stop altogether, especially if the lawn is not watered regularly. High heat, combined with dry soil, puts stress on grass plants, leading to dormancy.

While grass doesn’t die in a heatwave, it can go brown and appear dead. This is a natural survival mechanism. Once cooler, wetter weather returns, most lawns bounce back within a few weeks.

Heatwave Lawn Care Tips:

Avoid mowing too short—keep blades high to reduce stress
Water early morning or evening, deeply but infrequently
Avoid feeding—fertiliser can scorch dry grass

Can You Sow Grass Seed When It’s Hot?

While it’s technically possible to sow grass seed during hot weather, it’s not recommended—especially during UK heatwaves or mid-summer (June to August). High temperatures and dry conditions can cause seeds to dry out or fail to germinate, leading to patchy, weak growth.

Why Summer Sowing is Risky:

Seeds need consistent moisture to germinate
Hot weather can bake the soil surface, drying out seeds quickly
Young seedlings are easily stressed by heat and lack of water

If You Must Sow in Summer:

Sow during a cool spell, ideally after light rain
Water regularly (2–3 times a day in early stages)
Use a mulch or light top dressing to retain moisture
Opt for drought-tolerant seed mixes

Best Practice:

For the best results in the UK, wait until early autumn (late August to September) or spring (March to May) when conditions are cooler and rainfall is more consistent.

Garden Review UK

At What Temperature Does Grass Stop Growing in the UK?

At What Temperature Does Grass Stop Growing?