How -5°C Temperatures Can Affect Your Lawn

As winter sets in many homeowners may begin to notice changes in the health and appearance of their lawns. When temperatures dip below freezing, like it has over the last couple of nights to around -5°C (23°F) it can have significant effects on your grass and soil. In this guide we’ll explore how these cold temperatures impact your lawn, what you can expect and steps you can take to protect it during the colder months.

1. Impact on Grass Growth and Dormancy

At -5°C, your lawn’s grass will likely enter a state of dormancy. This is a natural survival mechanism that grass adopts during cold weather. Dormancy helps prevent the grass from expending energy on growth when conditions are unfavourable such as during winter’s freezing temperatures and reduced sunlight.

Most cool-season grasses found in the UK such as fescue and ryegrass can tolerate cold temperatures even down to this weeks -5°C, but they are not growing actively during this time. During this period, the grass could appear brown or yellow which is a normal response to the cold however this does not mean the lawn is dead. As the weather warms and temperatures rise these grass varieties will resume their growth cycle in spring.

2. Effects on Soil and Root Health

Soil temperature also plays a critical role in lawn health. When temperatures dip to -5°C, the ground will freeze. Frozen soil can restrict water and nutrient flow to the roots of the grass leading to stress however we have had enough water lately so this shouldn't be an issue. Grass roots become dormant as the soil temperature falls below 5°C slowing or halting root growth entirely.

While frozen soil can prevent water from seeping deeper into the ground, it can also lead to waterlogging in areas. As ice thaws water runoff may flood parts of your lawn potentially causing root rot or other moisture-related problems once the temperatures warm up.

3. Frost Damage and Foot Traffic

When the mercury drops to -5°C frost is common especially in the early mornings. Frost on your lawn can damage the grass blades. Walking on frosted grass, even lightly, can cause irreversible damage to the cells of the grass, leaving brown patches. Since the grass is not actively growing or repairing itself during this time any damage done by foot traffic or physical disturbances is more likely to remain visible once the snow melts and the weather warms.

It's best to avoid walking on the lawn during frosty conditions or when the grass appears covered with ice crystals. If necessary restrict access to your lawn and opt for other areas in your garden to minimise harm.

4. Ice and Snow Accumulation

In regions where snow accumulation is common during the winter months, ice layers can form on your lawn. Prolonged exposure to ice can suffocate the grass by preventing the exchange of gases with the atmosphere leading to conditions known as "snow mold." Snow mold is a fungal disease that thrives in cold, damp conditions and can create unsightly patches on your lawn when the snow melts.

While a layer of snow can provide some insulation and protect grass from extreme cold, thick, compacted snow or ice can cause significant stress to your lawn.

5. Preventing Winter Lawn Damage

While it’s impossible to stop the cold from affecting your lawn, there are several proactive measures you can take to minimise damage and promote healthy regrowth come spring.

Fertilise in Autumn: Applying a slow-release fertiliser in the Autumn before the ground freezes can help your lawn build up nutrients to survive the winter. A balanced fertiliser high in potassium will aid in strengthening the grass’s cell walls, making it more resilient to freezing temperatures and stress.
Overseed in Early Autumn: For cool-season lawns overseeding in early Autumn helps create a stronger lawn that can better withstand the cold. By giving your grass a head start before winter you increase its ability to recover in the spring.
Limit Traffic: Avoid foot traffic during periods of frost, and if you can, limit overall activity on the lawn during winter. If your lawn is prone to snow mold, try not to leave heavy snow piled up for too long.
Aerate and Dethatch: If your lawn has become compacted or has a thatch layer, aerating it before the winter sets in will help improve root health. This process allows better air and water circulation which can improve the grass’s resilience during cold weather.