Looking After Your Lawn In Winter

Try to rest the lawn as much as possible during winter. If practical keep off when wet or frosty, as the grass plants are not actively growing; if damaged, they will not repair themselves until the spring.

Mowing: Put simply, mow the lawn as and when it needs it ! Changing climate conditions now mean that lawns can carry on growing well into the winter, and giving the lawn a light mow every now and then is certainly a good idea. The frequency of mowing will depend upon weather conditions and temperatures at the time; do not mow if heavy frosts are expected, or if the ground is very wet.

Pests: Be vigilant for any signs of Leatherjacket or Chafer Grub infestation - as you are spending less time in the garden during the winter, damage can easily be overlooked. Fact sheets on Leatherjackets and Chafer grubs are available on request.

Aeration: Providing it is not done when it is frosted, aeration during the winter months will benefit the lawn. Aeration will relieve compaction, improve drainage, and allow more air into the root system, leading to a healthier, more vigorous lawn. Experienced gardeners sometimes talk about the beneficial effects of ‘getting some winter’ into the lawn. What this means is that when frost penetrates the soil via the holes caused by aeration, pockets of moisture in the soil freeze and expand, and this helps to break up the soil, thus maximising the benefits of aeration. In tests, grass roots have been shown to proliferate around the holes created, due to the ‘pruning’ effect of the tines cutting through the roots.

Clearing leaves and debris: This is important. Use a light rake or brush to keep the lawn free of leaves and debris. If left, they can turn the grass yellow and even kill it off by blocking the light. This can also contribute to moss development and weed ingress in areas where the grass has died back. Furthermore, the slimy, wet morass of decaying leaves can contribute to lawn disease. Specialist leaf sweepers and lawn vacuums are available for hire from local garden centres or DIY stores for larger lawns.

Worm Casts: Worms are beneficial to the soil structure of a lawn and also improve the nutrient content, but their casts can be unsightly, and if rolled into ‘pancakes’, can kill the lawn below. Of the 27 species of worm that are native to Britain, only 3 species produce casts. Worm casts are best left to dry and then swept or brushed away with a stiff brush. However, if required, we have a treatment which will control worm casts. Please ask for Fact Sheet No. 20 for further details.

Service your mower: Service or, if necessary, replace your mower now, ready for the next growing season, and whilst the dealers are less busy. Always make sure that the blades are in good condition and are sharp.

Snow Mould: This can be a problem. If you are concerned, please ask for Fact Sheet No. 22 for further details.


Thatch is a layer of organic material which can be found above the soil’s surface, but below the grass plant leaves. Thatch is defined as a tightly intermingled layer of dead, dying or living plant material, such as stolons, rhizones, stems, crowns, nodes and leaves – in other words, all parts of the turf grass plant.

In small, controllable amounts, thatch is very beneficial to the lawn, by preventing moisture loss through evaporation, and protecting the important meristematic regions (areas of growth, such as the crown, which can be found at the base of the grass plant). Thatch also provides a ‘cushioning’ effect for playing or walking on. However, poor turf management can quickly result in high levels of thatch and many related problems.

To determine the level of thatch present, a section of turf is removed. Looking directly below the green leaves, the amount of dark brown stem and root tissue is measured (see photograph below; the thatch layer is shown between the dotted lines). Thatch becomes a problem when it is any thicker than ½” or so.

An excessive layer of thatch will bring problems to a turf grass sward:

  • The lawn will feel spongy underfoot
  • Water filtration is reduced
  • It will provide an ideal food source and living conditions for many turf grass fungal diseases and insects
  • It increases the incidence of mower scalping the lawn
  • It will promote the growth and invasion of weeds, moss and weed grasses such as Annual Meadow-grass (Poa Annua).

The two main types of thatch found in domestic lawns are : The fibrous type (tough, dry, very wiry in feel, usually brownish in colour), which is typically found in acid situations, and the more common spongy type (yellow / brown in colour, usually soft and often waterlogged, and sometimes has black streaks running through it. This type often smells of eggs or stagnation (hydrogen sulphide), and will sometimes be found in heavily watered areas, or on heavy clay soils.

The benefits of controlling thatch through maintenance procedures such as scarifying, brushing and raking, and top dressing, frequently include : keeping a firm, dry turf surface, increasing the depth of the grass rooting system, and improved distribution and penetration of irrigation and rain water.

In addition, scarification will create space around the base of the grass plants, and new growth will be encouraged to fill the space, resulting in a denser, thicker sward of grass.

Usually the main option for addressing a serious spongy thatch problem has been scarification. Whilst there is a place for this operation, scarifying is a brutal operation which often has a severe effect on the lawn’s appearance, and can result in extensive overseeding being required. Where excessive thatch is the problem, there is now an alternative approach - Thatch Eater - which should be considered.

Thatch Eater is a combination of beneficial soil bacteria and fungi, specially selected for their ability to rapidly degrade thatch and other organic matter and to release locked-up nutrients for plant growth.

Applied after aeration, Thatch Eater will release a lot of the nutruent from the recycled thatch and promote healthy growth.

  • Degrades thatch and increases nutrient uptake into the grass plant
  • Improves surface drainage
  • Released nutrients encourage root development, not disease
  • Increases turf vigour and wear resistance
  • Promotes improved root development and sward density
  • Maximises the benefits of aeration


Moss is unsightly, and if left unchecked, can colonise a lawn in a short time, by winning the battle with the grass for the available nutrients, air and moisture. However, the main point to remember about moss is that it is merely the symptom of a problem, and not the problem itself. This may seem a strange statement to make, but the presence of moss is invariably an indication of poor growing conditions. It therefore follows that if those conditions can be improved, moss can be kept to a minimum. Simply killing moss and then scarifying it out is only part of the story; prevention is always better than a cure!

The main reason that moss survives on lawns is that the surface of the turf has become compacted, and as a result the grass roots find it difficult to establish themselves properly in the hard ground. Moss, being shallow rooting, has no such problems, and furthermore is able to thrive on the layer of moisture on the surface which is unable to drain away. (See also Fact Sheet No. 1 - Aeration).

However, there are a number of possible other causes:

  • Shade on the lawn - most particularly through the winter
  • Poor lawn nutrition - resulting in weak growth of grass
  • Lack of density in the sward
  • Mowing too closely - scalping is the main cause of cushion moss in domestic lawns
  • Allowing the grass to grow too long can contribute to trailing moss colonisation
  • Climatic conditions - mild, wet winters have seen an increase in moss in recent years
  • Drought in the summer can cause moss in the autumn

Treatment is therefore usually twofold; where possible, removing as many of the underlying causes (see above), and treating the moss with a chemical followed by scarification. In addition to removing the moss, scarifying removes the thatch which can impede drainage. Furthermore, scarification allows air to move more freely across the lawn; a major element in the construction of the new Wembley stadium is the ability of the roof to be reconfigured to allow air flow across the pitch, thereby increasing the health of the turf. (See also Fact Sheet No. 7 - Scarification).

Cultural controls include:

  • Removal of thatch (scarification) - to improve drainage, and allow air flow across the base of the grass plant
  • Thorough aeration - achieved by hollow-tine or solid-tine methods, to reduce surface compaction and improve drainage
  • Removing causes of shade if possible, or, considering using a shade-tolerant strain of grass seed
  • Improved lawn nutrition - to increase the strength of the grass, making the sward denser, which will eventually crowd out the moss
  • Changing the height of the mower to avoid scalping (See Fact Sheet No. 6 - Mowing)
  • Top dressing - improving the drainage by addition of a sandy or gritty growing medium, especially after hollow tine aeration