Lawn top dressing is when you apply a thin layer of material onto the lawn.
But lawn dressing is often done with sand and that’s where the problem is.
Sand is used because people think it will improve air space, water infiltration and drainage.
These are important goals, but topdressing a lawn with sand doesn’t help achieve them.
No matter what your soil is composed of, putting sand on top can actually cause drainage problems and dry pockets in the soil. And there’s more.
If you’re lawn top dressing with sand onto a clay soil, it can occasionally form a soil that is like concrete (depending on the type of clay).
Plus, sand doesn’t have much of any nutritional benefit itself – or any ability to hold onto nutrients.
(It’s not so detrimental to use sand on golf course greens because they’re already made of sand, but even then, it is not very helpful.)
But in thinking about how to topdress a lawn, there is something else commonly used in organic gardening that you should absolutely use for lawn top dressing and that is 1/4 inch to 1/2 inch of good quality, well-screened compost!
Well-made compost brings many benefits to the lawn and organic garden, including:
- a broad range of nutrients
- a huge diversity of beneficial microorganisms
- reduced thatch due to these microorganisms
- reduced disease
- improved water-holding capacity
- improved soil structure
- reduced compaction
So it’s this method of lawn dressing that should be done after aerating a lawn.
It’s ideal to do all of this after aerating because the amendments and compost get down into the root zone where they belong, but aeration certainly isn’t mandatory.
In fact, you shouldn’t need to aerate every year once your lawn is healthy, but topdressing with compost is always a good idea. You can do it spring or fall or both.
You can rent a top dressing lawn machine to do this, but I have never had much luck with it using compost. I just do it with a shovel and rake.
As I discussed in my lawn dethatching and lawn rolling post, dethatching is the last resort to use only when the thatch is simply too much.
The thatch will keep coming back until you address the root cause, which is inadequate soil microbial life. Continual dethatching will only exacerbate the problem.
Lawn rolling can be helpful during installation, but it is generally detrimental on an annual basis because it just compacts the soil, which is the opposite of what your organic gardening goals are.
As I discussed in my lawn aeration article, lawn aeration can provide benefits if done during the fall or early spring by a machine with sharp tines that removes the soil cores. It must be followed by topdressing lawn with good compost and optional other amendments.
Lawn dressing with sand is detrimental, but a good 1/4 inch to 1/2 inch of compost annually provides many benefits.
So if you’ve been aerating your lawn, I hope you’ll now topdress it after, and if you’ve been top dressing with sand, I hope you’ll use compost instead.
Here are some tips on where to buy compost.