Kill it, rake it out, then fix the reason it was there. Skipping the third step is why most people do this every spring.
Moss is a symptom
It does not out-compete healthy grass. It colonises ground where grass is already weak, and four conditions do that weakening.
Shade. Under a tree or on the north side of a building, grass never gets what it needs and moss does. This is the one that cannot be fixed with a product — it is a shade mixture, a thinned canopy, or something other than lawn.
Compaction and poor drainage. Waterlogged, airless soil suits moss and not grass. This is an aeration job.
Thatch. Holds water at the surface, which is a moss habitat. This is a scarifying job.
Cutting too short. Removes the leaf grass needs and opens the surface. This is a setting on your mower and it costs nothing.
Soil acidity gets blamed often and is a genuine factor less often; a soil test settles it rather than an assumption.
The order the jobs go in
- Treat, if you are going to — an iron-based product blackens moss within days. What any given product requires is on its label.
- Rake or scarify the dead material out. Thoroughly. There will be a great deal of it.
- Overseed the bare ground that is now visible, because otherwise something else will take it.
- Feed, to get the grass growing into the space.
- Fix the condition — aerate, raise the mowing height, thin the shade.
Done in that order, in spring or early autumn, it holds. Done as step 1 alone, it does not.
A note on iron
Iron-based products stain. Paving, a path edge, a pair of boots — the marks are rust and they are persistent. Sweeping the granules off hard surfaces before watering in is the whole of the precaution.
How this site handles it
The moss killer shelf here is the products whose stated purpose is moss. Combination feeds that also suppress moss appear on it where the maker names the function explicitly, and the page says the product is a fertiliser as well. Rates and precautions come from the label, which the page points at rather than reproducing.
Wherever this page and the maker’s own documentation disagree, the documentation wins. Every cutting width, cutting height, stated area, pack capacity, flow rate, head, sound level and application rate on this page comes from the maker’s own published figures, with the unit as printed and the source named. None of it is measured here, and no figure is converted into another convention, because a converted number is a different number. And the document this page hands back: the dose, the precautions and what a product may be applied to are on its label. That label is a legal text for a regulated product, and paraphrasing it would be rewriting it. This page reports the coverage and the analysis as the maker prints them, and points at the label for everything else.
The questions that keep coming in
Why does the moss come straight back?
Because a moss killer removes the moss and not the conditions. Moss colonises ground where grass is weak; unless the shade, compaction, drainage or acidity that weakened the grass changes, the same ground is available again next spring.
Should I rake the dead moss out?
Yes, and it is the part people skip. Dead moss left in place is thatch, it holds water at the surface, and it occupies the space the overseeding was meant to fill.
Last reviewed 26 September 2026