I am looking to buy a robot lawn mower for my newly laid lawn. These mowers are designed to make small cuts but to be used often. This I understand to be beneficial. They are capable of being operated on a schedule, mowing every day in the growing season or however you may specify.

I know Bowling Greens and Cricket Pitches are usually mown in the early morning, often while the dew is still on the grass, but I don't know if that is more to get it done before play starts rather than to benefit the grass.

Robot mowers can be set to run in the middle of the night or at noon under full sun. As I'm not doing the work I'm happy for it to run at 3am.

Is there an optimum time of day to mow grass, or is the weather more important?

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    If your robot is making noise while mowing it might not be good idea to use it during night... On the other hand, where is the fun if you are not mowing? :) Commented Nov 27, 2017 at 11:00
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    Bowling greens and cricket pitches are mown early morning for the practical reason that they are used during the day. Also the equipment used to maintain such types of very shortly mown lawn are very specialised. Also worth noting perhaps that shortly mown lawns require a lot of maintenance to ensure that they grow well. Commented Nov 27, 2017 at 21:01

3 Answers 3


You're in the UK - that means the grass will be wet or damp overnight throughout the year with the exception of the summer months (June to end of July), and only then if its not raining, so this would rule out letting it run during the night. Whether or not a model can operate in wet or damp conditions should be one of the features you check for prior to buying, but generally, lawns are not cut when they are wet largely because the cut won't be so good as when the blades of grass are dry, and mud slicks may occur (sports turf is a different matter).

You might be interested in this https://news.turfonline.co.uk/want-buy-robot-lawn-mower/ because you need to take into account whether you will always be able to keep the lawn cut year round. It's not usual to cut the grass regularly during winter in the UK, but that might mean, if you buy the wrong model, yours won't cope with grass six inches long in early spring.

Because of the weather conditions in the UK, the best time to cut the lawn will actually be in the middle of the day, more or less, although later or earlier than that in summer will be fine. Security could be an issue if you leave the mower outside all the time, so hopefully, your garden is not very easy to access when you are not there; you might want to consider a model that has extra security features. In regard to lawn maintenance ongoing, note that the routine mentioned elsewhere as appropriate in USA is not the recommended routine in the UK; we have a somewhat different recommended regimen. If you need more information on that, try to get hold of a copy of 'The Lawn Expert' by D. G. Hessayon for expert guidance. At least one of the chemical treatments mentioned in it may be out of date or banned, but the basic guidance is still relevant and very useful.


I don't have too much experience (none with robot mowers) but I think same 'rules' apply to any type of mower:

  • Avoid mowing when grass is wet - this applies to early morning when there is dew (or after rain). Mowed wet grass is sticky and will probably pile up inside you mower.
  • Also, the hottest time of day is not good time because your grass it trying to keep in moisture.

This leaves late afternoon or early evening as best time to mow your lawn. The grass is likely to be dry and sun not too strong to sap moisture.

Tbh, buying robot mower seems like a rather big investment (prices range from few hundred to couple of thousand EUR depending on size, speed, various features and area you are mowing) and they are probably nowhere near reliable, robust or easy to service as ordinary mowers. It is probably best to follow instructions/manual provided by manufacturer.


Since you've got cool season grass mix for a lawn you will want to make sure that that mower cuts no lower than 3". Once a week, twice is better. Bag clippings. Mow in the early afternoon when the dew has evaporated off the leaves. Hey, I had to mow no matter what, rain or shine. Mostly down pours 7 out of 10 days. Sharp blades and hydrostatic mowers were important. Sharp blades...cleaned with alcohol in between customers.

Security issues that Bamboo brought up sounds like a very good thing to be aware of...learn the rules of watering, fertilizing, aerating cool season grass mix lawns. Just cutting the lawn is not the only aspect for a beautiful crop of grass. Edges, fertilizing 4X per year...with season specific fertilizer formulation, watering deeply and not watering until you are able to see your footprints stay down on the lawn is crucial, water during the day, never in the evenings or during the night.

Bagging is very important. I haven't found a real mulching mower with mulching capability ever. Bagging the clippings is easy and those clippings are gold for killing weeds and composting. Allowing them to remain on your lawn is asking for expensive thatching and lawn renewal within 5 years.

I'd hire someone to mow your lawn with a hydrostatic mower, sharp blades, aerate once or twice per year, dump clippings thinly on weeds, fertilize, check pH and readjust when necessary...for the price of a robot mower, you could employ someone that would be able to notice problems before those problems happened. If you hire someone that has multiple customers, insist that their blades are sanitized before they mow your lawn.

Never mow your grass shorter than 3". Golf courses use different seed mixes than most residential lawn crops. Your lawn mix has huge root systems and too short of grass means wimpy photosynthesis that means too little carbohydrates being made to support the roots as well as the top growth. Weak grass is susceptible to disease, insects and weeds. Cool season grasses cut shorter than 3" (3 1/2 inches is best) are very stressed and are unable to compete with weeds...winter.

What is happening with line trimming the edges? The edge is what the eye sees. As long as the body of the lawn is a uniform green and texture, it is the edge of the lawn that creates the professional punch.

And I just have to add this; I've learned that the hours, the WORK maintaining landscapes...it was the mowing and edging that made all worthwhile. To be denied the chore of maintenance and connecting somewhat to your garden is denying you health and joy. Just sayin'. Having to get out and do chores actually gets us out of the house, away from the technology, daily stresses, the clock, to allow sun on our skin, fresh air, huffing and puffing.... and the benefit is clarity of mind, objectivity with emotions and stress and simply feeling a part of something larger. Woo HOO! This is just my perspective, grins.

  • "Security issues that Bamboo brought up sounds like a very good thing to be aware of...learn the rules of watering, fertilizing, aerating cool season grass mix lawns." - those were not the issues Bamboo mentioned :) Also, OP is considering using robot mower and question is about optimal time of day or weather conditions for mowing... Commented Nov 28, 2017 at 8:41
  • I don't know anything about mulching grass, but if the robot will be mowing everyday, would it matter how good the mulching is? Or would the worlds worst mulching robot still be good enough?
    – Rick
    Commented Nov 28, 2017 at 19:31
  • Grass becomes thatch when the cut grass leaves don't keep up with decomposing fast enough, they actually cause a barrier to the bacteria necessary for decomposition. I am unable to imagine any machine being able to do the composition necessary fast enough...no matter how small the clippings have been made. The clippings take 2 or 3 weeks to decompose. You mow every week, possibly twice a week. The clippings will never be able to decompose fast enough to keep up with the fresh debris. I've just got to go out and take a look at this! Thanks...
    – stormy
    Commented Nov 29, 2017 at 0:22
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    @FalseIdentity I should have used a period not an ellipsis. This is a huge expenditure. Having a robot mowing away autonomously is a brand new concept here and there are far more important considerations I think I could bring up to help with this decision. Grins, shoot me. I am a human not a machine that spits out the simplest yet correct answer imaginable. I answered the correct time of day and gave him more to think about. I've never even thought about robots mowing lawns, doing the job I ran for over a decade. This is a great subject!
    – stormy
    Commented Nov 29, 2017 at 0:29

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