You can, and it is worse in four separate ways. None of them is catastrophic, and on a British or German spring you will sometimes have no choice.
What goes wrong
The cut. A mower depends on airflow standing the grass up before the blade arrives. Wet blades are heavy and lie flat, so a proportion of them are struck at an angle and torn. The lawn looks fine for a day and then the torn tips whiten.
The deck. Wet clippings pack under the housing into a dense mat. That mat blocks the airflow the cut depends on, so the machine gets worse as it goes, and it has to be scraped off afterwards rather than brushed.
The load. Heavier material, more of it stuck to everything, and a restricted airstream. On a cordless machine the runtime falls noticeably; on a petrol one the engine labours.
The ground. Soft turf takes wheel marks, and a heavy self-propelled machine on saturated soil compacts it. On a lawn that already drains badly this is a real cost, and it shows up as a thinner sward later in the year.
If you have to
Raise the height a setting, which reduces the volume passing through. Slow down. Empty the catcher early and often, before the mat forms. Consider removing the catcher and side-discharging or mulching, so the deck has less to move. And scrape the underside out before putting the machine away — a deck left to dry with a packed mat in it is worse to clean a week later and starts to corrode.
What is not worth the trouble
Mowing a waterlogged lawn at all. Nothing is gained, the finish is poor and the surface damage lasts.
How this site handles it
Deck material and mass appear on every mower page here, because they are what decide how a machine behaves in the wet — a stiff deck holds its airflow and a light machine marks soft ground less. No page here states that a machine is safe to use in any condition, and none of the shelves is described as weatherproof on this site’s own authority.
The questions that keep coming in
Is it dangerous with an electric mower?
The machines are built for grass that is damp — that is the condition they live in — but a mains machine outdoors should be on a socket protected by a residual current device, wet or not. What this site does not do is tell you an installation is safe.
Why does the cut look torn after rain?
Because wet grass lies down under the airflow instead of standing up, so the blade hits it at an angle and tears rather than slices. The tips go white a day later, which is the visible form of the same problem.
Last reviewed 26 September 2026