It’s generally held that healthy, vibrant grass needs equally healthy soil to flourish - soil that’s well-drained, nutrient-rich and packed with healthy microbes: Soil that has a good structure, that’s not too sandy, and that’s home to a thriving ecosystem.

A good pH level helps too, as does having the right balance of particulate matter, which plays a pivotal role in ensuring that grass roots can reach the pockets of air and water that they need to grow.

Unfortunately, it’s very difficult to change the composition of garden soil once a lawn is properly established. Most common methods of correcting structural and/or chemical issues involve digging in large amounts of organic matter, which would destroy grass roots and cause damage that far outweighs the negative consequences of leaving a significant compositional imbalance unchecked.

This means that correcting any  imbalances affecting the health and wellbeing of your lawn can be very difficult after the fact - bad news if you’ve only just started to see the symptoms of nutrient deficiency popping up, or have inherited a lawn from less savvy gardeners.  

Topdressing is one of the few options open to you. Topdressing, for the uninitiated, involves  dressing the surface of your lawn with fresh sand or soil and is one of the only ways to influence the contents, makeup and health of your soil without damaging the delicate ecosystem of your lawn. Particles of topdressing preparation scattered over the top change the composition of the surface layer, and help to create a smooth, flat surface that prevents water from pooling after heavy rain. Particles scattered over the lawn after core aeration filter down into the soil beneath and help to boost grass growth by correcting any imbalances, and particles scattered after scarification help to keep thatch down by introducing a greater proportion of the beneficial micro-organisms needed to stop grass stalks and other dead matter from building up to an unhealthy degree.

The process of topdressing is slow, and you’ll probably find that you have to repeat the process on a fairly regular basis to achieve the desired effect, but it is a highly effective way of promoting the growth of healthy grass, and, unlike more invasive methods, will allow you to address issues without damaging the very thing that makes your lawn so attractive in the first place.

Should I be Topdressing?

As mentioned above, there are four main reasons for topdressing a lawn: Firstly, topdressing will help you to level out any bumps, divots or hollows, making it ideal if you want to keep your lawn smooth and level. Secondly, topdressing is a reliable way to protect grasses from desiccation, particularly in winter, when cold winds can strip moisture from over-exposed grass crowns.

Thirdly, sand-centric topdressing can, over time, improve the drainage of soil by helping to even out an overabundance of clay-like soil particles, which allows water to drain off properly. Finally, and perhaps most importantly, long-term topdressing regimes can change the overall composition of your soil

The way that you topdress, the material that you use and the timing of your restorative efforts will vary greatly depending on the reason that you’ve chosen to topdress your lawn, so we’ve broken down the best possible strategy for each individual application below.

There are a few universal rules though; you should only topdress when grass is actively growing (i.e. never in the depths of winter) because topdressing can suffocate inactive or dormant plants. Topdressing also creates a small microclimate, and can encourage the spread of disease if overdone in very warm weather. As such, most seasonal topdressing is done in late spring or early autumn, and you must take care to brush in the topdressing material after spreading it; using a rake, or a towed lawn tractor attachment designed for the purpose.

This is to make sure that the material is spread evenly over the surface. Clumping of topdressing soil, compost or sand can cause uneven drainage, and lead to the development of wet and dry patches that stop your grass from growing properly, and leave your lawn looking patchy.

Top Dressing to Level a Lawn

Patches of bumpy ground, shallow depressions and small hollows can appear for a variety of reasons; from children playing, right through to the wear caused by other turf care activities.

These uneven areas allow water to pool during heavy rainfall, which prevents even drainage and causes significant damage by saturating grass. Shallow depressions and divots also make mowing your grass difficult, particularly if you’re using a wheeled mower, and often end up making your lawn look patchy and untidy.

If carried out correctly, topdressing will allow you to fill these uneven areas; leaving you with a smooth, healthy lawn that drains properly.

This is particularly important if you find a lot of silty worm castings on your lawn. These castings, caused by burrowing worms, can trap soil against the surface and significantly impede drainage. You’ll also definitely want to consider topdressing to level your lawn if it receives a lot of heavy wear, as unchecked wear can quickly wear barely-noticeable grooves into your lawn, and there’s a good chance that you won't notice this happening until your lawn starts to look patchy and dog-eared.

In terms of the actual process, you must take care when topdressing to level your lawn: You want to apply material to the affected area in thin (¼ inch) layers so that you don’t accidently affect the overall composition of your soil , and you’ll also want to make sure that you fill problem areas with a relatively level amount of your chosen topdressing application - so that you don’t accidentally over-fill, and cause the opposite problem.

One way to apply topdressing material is to scatter it gently with a spade or shovel. If you really want to make sure that you’re applying an even layer of soil, we’d definitely recommend that you also consider a . Although they are a slightly more price-intensive option, these fantastic machines

If you’re just looking to level your lawn, you’ll also want to pay close attention to your chosen application. You can top-dress with sand, or with a sand/soil mix, but you’d ideally want to match the profile of your existing soil as closely as possible, so as to ensure that you don’t inadvertently change any of its properties. The best way of identifying the composition of your soil is to take a core sample, and have it analysed. This guide also provides a fantastic DIY method though.

In terms of timing, we’d recommend applying a thin layer of topsoil at the beginning of the season, and again before and after any periods of prolonged activity are expected.

If top-dressing before the grandkids/rival sports team come round, we’d recommend that you do it at least a few days beforehand though -  just to make sure that they don’t end up trampling your carefully-formulated application across the garden.

Top Dressing to Protect Your Grass

In lieu of expensive lawn covers, you can topdress to protect your grass from desiccating winds and sudden chills; a pair of oft-underestimated winter hazards that can cause significant damage to delicate lawns.

The intention here is to insulate the crown of individual grass blades, which prevents them from rapidly drying out. The crown is the part of the grass plant that bridges the gap between root and stem (there’s a handy diagram here) and is a major nutrient repository that’s responsible for fuelling future growth. As a result, the crown is the part of the plant that’s most vulnerable to desiccation.

To protect it from sudden chills, you want to apply quite a thick (½ inch) layer of your chosen topsoil application; taking care to make sure it’s an even layer so that random patches of grass are not left exposed. You can do this by hand, or by using a … which is designed to ensure that material is distributed evenly over your lawn.

In terms of the material that you should apply, a lot of golf courses use pure sand to protect grass before cold snaps, but this is largely to do with the fact that sand is a cheap, expendable resource. Any topdressing material, applied in a relatively thick layer, will do a good job of protecting your lawn so there's no particular reason to opt for anything other than sand, but if price is not an issue, you should definitely try to pick something that’s close to the natural composition of your soil, so as to avoid altering the composition too much.

If you’re just applying topsoil to insulate your lawn, you can wait until a cold snap is forecast - there’s no particular reason to do it earlier, and there’s no real benefit to doing it more often.

Top Dressing to Improve Drainage

If your soil is particularly rich in clay particles, you will probably find that drainage represents a significant issue; with your lawn getting waterlogged after heavy rain or prolonged wet periods. Clay heavy soils are also particularly susceptible to wear and tear, crack after being dried out, and warm up very slowly in spring and summer, which can inhibit plant growth - leading to stunted grass.

Obviously this isn’t ideal, and the most common methods of correction; namely working in more sand, or adding calcium, can’t really be done once a lawn is established. As the Royal Horticultural Society point out, you would have to add 250kg of grit or gravel per square meter if you wanted to reduce the proportion of clay by 50%, and even if you could do this without completely destroying your lawn, you’d also have to mitigate the fact that adding large amounts of granular matter to your soil would significantly destabilize it,causing a host of structural issues.

Topdressing can help to improve drainage though. By slowly adding small amounts of sand or grit, you can gently alter the overall structure of your soil so that water drains through at a normal rate. To achieve this, you’ll need to topdress after you’ve aerated your lawn. This will allow sand and grit to penetrate the surface and filter down. Over time, and through repeated applications, this will break up the concentration of clay particles and leave you with a more balanced soil.

When it comes to actually applying the topsoil, you should spread your chosen preparation in an even layer, letting it collect in the aeration holes on its own. Spreading in an even layer will prevent clogging of the aeration cores, which can be damaging in its own right, and it will also prevent your lawn from becoming uneven, which can cause its own selection of issues in the long term.

In terms of the mix that you use, some care is recommended: Although it might seem logical and expedient to use pure sand, doing so will cause the same structural issues mentioned above. Instead, we would always recommend a mix of equal parts sand and soil, or two parts sand, one part loam and one part regular soil to ensure that some consistency is maintained.

Top Dressing to Correct Compositional Imbalance

Top dressing to correct overall soil composition is very similar to topdressing to improve drainage; it should also be done slowly, over time, by adding thin (¼ inch) layers over soil that’s recently been aerated. It should also be done on a semi-regular basis, allowing for the temperature-related recommendations in the ‘Should I Be Topdressing’ section of this document, and you should also take great care to ensure that your preparation is not so imbalanced that it will damage the integrity of your soil structure.

The only key difference is that you’ll want to ensure that the top dressing mixture matches your desired end goal, so if you’re trying to address an over-abundance of sand in your soil, add a clay heavy mix, and if you’re trying to improve filtration rate and/or general soil structure in a loamy soil, do the opposite.

For exact measurements, proportions and an in-depth guide to soil composition, you’ll find the Royal Horticultural Society’s guide to buying topsoil particularly handy.

And we’d recommend being very careful to maintain the composition of the preparation that you choose to use over time: Consistency is key, and once you’ve settled on one particular type and makeup, you’ll need to stick to it rigorously because deviation can cause layering; a process that prevents proper drainage, and can, over time, severely damage your chances of improving the health of your lawn.

If you’d like more advice on topdressing to improve the overall composition of your soil, or have general questions about topdressing in general, you can always reach us on… We’re always happy to help point people in the right direction, and we take pride in the fact that we openly share our knowledge and expertise with the people that need it most.