Complete guide to top dressing a lawn

What is top dressing a lawn?

Top dressing is the process of renovating a tired, patchy, or bumpy lawn or achieving a high-quality lawn by adding a thin layer of bulky dressing to the surface. This encourages fresh, healthy grass growth and provides ideal growing conditions for new grass seed to grow. Lawn top dressing mix is made up of sandy loam or good quality free-draining topsoil, along with sand and well-rotted organic matter. Either make this up yourself or buy lawn dressing ready to use.

The job of top dressing is quite hard work as the material is heavy, bulky, and needs to be evenly spread, so for most garden lawns, top dressing is regarded as an occasional task to do if necessary, rather than part of an annual lawn care regime.

Be aware that lawns treated with top dressing are likely to look messy for at least a couple of weeks until the grass regrows, and you will want to avoid treading on it until the grass has started growing through it strongly.

When is the best time to top dress a lawn?

Early to mid-autumn is the best time to top dress a lawn, to help the grass recover from summer’s wear and tear, and from any extremes of the season’s weather. However, only top dress when growing conditions are good and the grass is growing vigorously.

How to top dress your lawn

Top dressing is usually done as part of an autumn lawn care programme, but it can also be done in late spring. Start by scarifying and aerating your lawn, then top dress before adding grass seed to thicken up any bare patches.

When top dressing, usually aim to apply around 2-4kg of lawn dressing per square metre, or up to 6kg if the lawn needs a heavy dressing. The amount needed will vary depending on whether there are hollows or drainage channels to fill in. If you’re not sure how much to use, start with a smaller amount – it’s much easier to add more rather than try and take it off or move it around. Only top dress when the lawn is dry and the weather has been reasonably dry, and you can be sure of finishing the job before it rains again.

1. First mow the grass with the mower set to a low level for a short cut, but without scalping the lawn. Then wait for the grass to dry completely
2. Using a shovel, spread the lawn dressing as evenly as possible, using a fan-shaped motion for spreading rather than dumping the dressing in one spot
3. Using a rubber rake or the back of a straight-headed metal rake, work the dressing into the grass and into any hollows or holes. The aim is to work the dressing into the root zone so the grass is visible, not to smother the grass
4. For the best finish, go over the lawn with a stiff long-handled garden broom
5. Avoid mowing the lawn for at least a week, ideally two. If there hasn’t been any rain in that period, water the lawn before mowing so the top dressing settles thoroughly, or the mower may pick up the top dressing into its grassbox

How to make your own lawn top dressing mix

Top dressing mix is not the same as topsoil but this is one of the main ingredients. The best soil mix for top dressing lawns is made up of soil (loam), sharp sand and organic matter such as fine compost or leaf mould. Make your own top dressing is possible but it is quite hard work, and it’s also likely that you’ll need to buy most of the materials required. A top dressing lawn mix is made up of three parts sharp sand (not builder’s sand), six parts good sandy/loam weed-free topsoil, and one part peat-free compost (such as coir) or sieved leaf mould. You’ll also need a bucket as a measure, a shovel, a wheelbarrow and a clean, hard surface or a tarpaulin on which to mix the material.

What is top dressing and overseeding?

Adding new seed to thicken up an existing lawn is known as overseeding. The two actions combine particularly well together as the lawn dressing provides an ideal rooting environment for grass seed. Spread grass seed after completing top dressing to achieve an even spread of seed. Rake lightly to work the seed down into the root zone. If there’s no rain after a day or two, water the lawn and then keep it moist until the seed germinates.