Can you cut wet grass with a lawn mower?

We’ve all been there. The rain has just passed, the sun peeks through and you look out at your lawn that suddenly seems twice as long and very much in need of a trim. Obviously the best course of action would be to wait a few hours until it’s dried sufficiently. But what if this is the only chance you’ll have all week to give it a mow? What if some guests are due to arrive, or you’re booked on a holiday flight in four hours and if you don’t mow the lawn now, chances are it’ll look like a meadow when you get home?

Sometimes having to mow after inclement weather is a necessity, but is mowing wet grass a good idea? The short answer is no it’s not ideal, mostly because wet grass easily clumps, sticks to mower blades and almost always cakes the underbody with an inch or so of compressed cuttings that can inhibit the mower’s ability to fling grass cuttings into the grass catcher.

All that caked-on grass adds a lot of extra weight to the mower in general which, in turn, makes it much more difficult to push and turn. Furthermore, as highlighted in our expert guide to 5 reasons why you should never mow wet grass, the ground itself may be softer than usual and the weight of the mower and its wheels could compact the soil.

However, if you absolutely must mow a damp or wet lawn with your best cordless lawn mower, best petrol mower or best robot lawn mower, here are seven smart tips to help you – or your robot – do it more effectively.

1. Sharpen your mower blades

Wet grass bends easily under the mower, which can leave the lawn looking uneven and ragged, especially if your blades are dull. A sharp blade makes a clean cut and reduces tearing, which helps the grass recover much more quickly. For more advice, read our handy guide on how to sharpen robot lawn mower blades.

2. Raise the cutting height

The last thing you want to do is scalp the lawn when it’s wet, so set your mower to a higher level to avoid cutting too much at once. I would suggest a minimum of 40mm (level 4) on a push mower and 40 to 45mm on a robot mower. This will reduce stress on the grass and prevent the mower from choking on heavy clippings.

3. Side-discharge or mulch?

Bagging wet clippings is difficult since they clog the bag quickly and the extra weight of the grass means that some of them may not reach the bag at all. But on the plus side, a grass collector ensures fewer damp cuttings littering the lawn.

If your mower has a mulching feature (all robot mowers use the mulching technique), use it sparingly on wet days so as to avoid thick clumps from gathering and blocking sunlight from the lawn, turning it yellow in the process. However, if your mower has a side discharge option, I would recommend using it because it spreads cut grass clippings over a wider area.

4. Keep it slow and steady

Wet grass is heavier, so mowing at your usual pace may clog the side chute or stall the engine or electric motor. A slower, deliberate pass ensures a more even cut and less mess. Also, when approaching a particularly tall section of grass, tilt the mower back off its front wheels by an inch or two so the blade has a better chance of making a cleaner cut.

This tilting technique also prevents the mower's electric motor or engine from bogging down. Chances are the length of the grass in this section may now be a fraction taller than the rest of the lawn but that’s no problem because you can simply do a second run over the same section with all four wheels on the ground. Finally, try to make your turns as carefully as possible to avoid churning the lawn, especially if the ground is soft.

5. Clear the cutting deck regularly

Moist clippings stick like glue to the underside of the mower deck, blocking airflow and leaving thick ugly clumps under the deck. Stop occasionally, turn off the mower and scrape away the build-up using a simple paint scraper. The same goes for robot mowers which can easily increase in weight through caked-on clippings, reducing their battery running time in the process.

6. Watch your step

Wet lawns are slippery so wear sturdy shoes with good grip and always mow across a slope rather than up and down to reduce the risk of slipping backwards on your butt or, worse, forwards your face.

7. Dry the grass afterwards

If you’re left with clumps of wet clippings, rake them up once the grass has dried. This prevents fungal problems and ensures sunlight reaches the grass blades beneath. If you just leave it all lying there, the living grass beneath will start to rot and no-one wants a rotting lawn.