Although it is not ideal to start cutting wet grass, there are times when this is the only option available as it may have started to rain part way through the grass being cut. Cutting wet grass can lead to problems as it is often difficult for the petrol mower to collect the cuttings in the grass collector located either at the front or the rear of the mower.
Grass which is cut using a petrol lawnmower or electric lawnmower can create different sizes of grass clippings which depends on the height of the cutting blades. When the mower operates as a mulching lawnmower, it can often displace the clippings through the side chute. This is sometimes the most efficient way to recycle the grass clippings back onto the lawn. Some specialised mulching lawn mowers do not always have a side chute on the mower. It is apparent if they are able to mulch the grass as they have a specific mulching cutting blade. This lifts the grass cuttings into the cutting deck and the air generated by the spinning blade helps to circulate the clippings around the deck. The circulating blade tries to cut the clippings for a second time and then blow them evenly out beneath the deck, so they can be distributed over the lawn without clumping. If the grass is wet then it will obviously make it harder to lift the blades of grass through the cutting action as the grass will be heavier and will stick to the rotating blade and also to the underside of the cutting deck. Avoid leaving wet grass to settle on the lawn in clumps because the damp conditions under the clump will encourage fungal growth and damage any healthy grass which is trying to grow beneath. If any grass is left on the lawn which has been missed by the collector it would be better if the lawn is lightly raked.
Why should you not cut grass when its wet ?
There are various reasons why you should not cut grass when its wet, but the main reason not to cut it would be for the safety of the lawnmower operator. It would be reasonable to assume that if it was raining you would not continue to use an electric lawnmower in the rain to avoid electrocution. However, if you use a petrol lawnmower then these machines can quite easily operate while it is raining. There would be other factors such as slipping or skidding of the machinery which would be a risk of harm. When grass is wet the grass blades fold over with the weight of the water rather than stand upright which results in some blades of grass being missed in the cutting process when the mower blade travels over the surface of the lawn. Any weight from the lawnmower rollers or wheels will flatten the blades of grass underneath and these will be missed in the normal cutting process.
When cutting wet grass with a petrol lawnmower more stress is placed on the engine during use and this may over time reduce the life of the motor as the engine needs to work harder to rotate the blades as they become heavier with the wet grass. The lawnmower will also find it harder to operate through the wet grass as the wheels start to bog down and slip. Self propelled systems on lawnmowers rely on the engine being able to power the wheels which reduces the need to push the lawnmower by the operator. It is also important that all wet grass clippings are removed from the underside of cutting deck on the lawn mower as these parts are usually made of steel and will over time rust if the moisture is retained.The grass collection bag or box should also be cleaned of any grass debris or leaves when it is emptied during lawn mowing. If the air is not able to circulate around the grass collector it will be harder for the clippings to be sucked into the collector and be dragged to the back of the box. If the sides of the grass collector are free from debris it will allow the collector to circulate efficiently.
There are some petrol mowers which have a self cleaning facility on the mower which allows the underside of the mower deck to be washed when connected to a hosepipe through a connector positioned on the top of the cutting deck. If your mower deck is constructed from aluminium then rust should not be an issue and the lawn mower will also be lighter to lift.
Rotary and cylinder mowers will also find it more difficult to collect the cut grass and then propel it into the collection basket on the rear or front of the mower as it becomes heavier due to the moisture in the grass. The extra weight of the grass in the collection box will also put more pressure on the self drive assembly. Try to empty the grass collector more regularly if it is wet and clear the grass which collects on the underside of the mower as this build up will also reduce the air flow underneath the mower. Mowers which have a roller on the rear of the machine will find it difficult to produce the desired stripe effect which these lawnmowers are renowed to create. The stripe effect is created by the roller which flattens the grass in a particular direction of travel (perhaps away from you) and then on a return in the opposite direction the grass is bent towards you which gives the effect. The weight of the water on the grass will flatten the grass so it does not bounce back in certain passes of the mower to reflect the light correctly and produce the dark / light effect for the stripes.
How do you cut long wet grass ?
The best way to cut long wet grass is to displace some of the surface water from the grass initially by sweeping with a plastic head brush and long handle. If it is a large lawn then maybe drag the surface of an opened hosepipe across the top of the lawn.When the grass is very long, such as knee height then it may be appropriate to first use a petrol strimmer to reduce the length to a more manageble height. Remember to try not to remove more than a third of the height of the grass if possible to reduce any further damage to the lawn. This may not be possible if the grass is very long as it has possibly been left untreated. When the grass has been strimmed there will be areas of the lawn which will be lighter or yellow/brown in colour as the grass at the base may have been restricted of any light for a long period. The green pigment will return to the lawn over a period of weeks as the light and nutrients return to the grass.
Adjusting the height of the cutting deck on the lawnmower will also help when cutting the wet grass. Set the lawnmower at the maximum cutting height for the machine for long grass and cut all of the lawn at this height. Then conduct a second pass of the lawn after reducing the cutting height of the deck again until the desired height for the grass is reached. Remove any wet grass clippings with a grass rake from the surface of the lawn, which may have been missed by the grass collector. Try not to remove more than a third off the length of the blades of grass as it causes stress to the lawn. Cutting the grass later in the day or on a windy day after it has rained will allow more of the rain to evaporate from the lawn.
Grass grows very quickly during long periods of rain followed by sunny intervals as this is the optimum conditionsfor rapid growth. If this is combined with regular feeding of the grass and lawn fertilizer, it would be normal for the lawn to be cut at least once every 2 weeks to ensure that the grass is maintained and weeds are kept to a mimimum in the lawn.
What are the best blades for cutting wet grass ?
In order to mow wet grass to keep it neat and tidy it is necessary to ensure the lawn mower blades used to cut the lawn are sharp and in good condition. If a sharp blade is used the grass should be cleanly cut which leaves a sharp edge on the blade of grass. It can be quite noticeable if a dull blade which is not sharp has been used to mow a wet lawn. Generally the lawn has a misty dull appearance as you look across the grass which is due to the light bouncing irratically off blades of badly cut grass as it reflects the light back off the lawn.