I don’t know about where you may live but here in London we have a city that is essentially built on top of mud and clay. I’m really not joking. The place is one giant lump of clay that had a city built on it.
Not only that, it is also a giant lump of clay in one of the rainiest, dampest countries on earth. Now I’ve managed to grow pretty good lawns in quite a few places around the world, but I’ve struggled in London because every winter my small postage stamp of a garden turns into one soggy, muddy bog. Whatever grass managed to struggle above the surface in the summer ends up a straggly, matted mess that gets squashed back into the mud. If you think I’m kidding just take a look at the photo to the left and you’ll see what a muddy mess my lawn was.
Anyhow it took me a while to figure out how to fix it and the solution was to start applying top-dressing to the lawn. There is no real mystery or magic to lawn top dressings. The better ones are nothing fancier than a mixture of compost and sand. The compost helps to feed the soil and the sand helps to improve drainage and airflow into the roots. Quite simply, it takes mud and clay and turns it into real soil that doesn’t compact down and get all waterlogged. That helps reduce the amount of mud and stops the grass getting trampled down into the soil.
When to apply top dressing to lawn
You should apply top dressing at least once a year and more often if needed to improve a very poor quality soil and lawn. The ideal time to apply it is in early spring when the soil is not too wet. That said you can also apply it throughout much of the growing season. You should probably avoid doing it in mid-winter.
Apply it so that it is no more than a quarter of an inch thick and work it into the lawn with a brush or rake. Then water the lawn. After a week or two the grass should have grown through and you can mow it as normal.