Whilst caring for our clients’ lawns over the years throughout Surrey we see a vast improvement in lawn health and appearance in those lawns that are mowed and watered using these key principles as a guide:
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Our general recommendation is to keep your lawn at a height of 25 mm – 40 mm (about 1 inch to 1.5 inches). Of course every lawn is different and should be treated as such, however, this is a good benchmark for a domestic utility lawn. If areas of your lawn are in constant shade or little light it’s better to raise the height to allow more grass blade on show for photosynthesis. A lawn that is cut too short will become thin and invite opportunity for weeds and moss to take a foothold, a lawn that is cut too long will become leggy, look untidy, and encourage moss and disease.
How to set the right height on your rotary mower
Aside from checking the owner’s manual, the most effective way to check the height settings on your mower is to place your mower on a flat hard surface, such as a patio, with your mower off and spark plug or battery removed place a stick inside the housing, try and find the lowest point of the mower blade and place the stick on the hard surface below the blade. Mark on the stick where the mower blade reaches and measure the distance using a ruler or tape measure.
The lowest setting on the mower isn’t necessarily the correct one – each mower is different and it’s important to know what height you’re cutting at. It’s best to start high and work your way down if you’re unsure.
To prevent stress it is really important that only 1/3 of the lawn height is cut each time. If due to conditions or time constraints the lawn gets long I advise slowly reducing the height of the cut over a week or two. Removing more than 1/3 of the blade length will thin out the sward leaving it vulnerable to moss, weeds, and in some instances, weaken the lawn against disease. The best greens are only cut a few mm a day. Little and often is the best approach when cutting a lawn. A lawn that is regularly cut little and often will be in far better condition than a lawn that is cut infrequently and with more than 1/3 removed each time.
Increasingly we’re seeing clients with robotic mowers. The robotic mower is out cutting the lawn 3-5 days a week come rain and shine, the results are impressive. Not only is the lawn being cut little and often but the grass clippings get mulched back into the lawn – free food and no waste!
The domestic lawn typically has a mixture of grass types and cultivars. Some grasses including the bents and fescues create stolons and runners – these can cause quite an issue if a lawn is always cut in the same direction.
You might have noticed your lawn looking thin and ‘leggy’ and can’t understand why. This is quite common, we see this in lawns where the direction of the cut isn’t alternated. Overtime, instead of growing vertically, the lawn starts to grow horizontally in the direction it’s being pushed down by the mower – know as ‘graining’.
Horizontal growth causes an issue where the grass plant gets long and the lawn becomes thin – no matter how low you try and cut the lawn it won’t take enough of the height off.
By alternating direction 45 or 90 degrees on each cut e.g. from north/south to east/west or diagonally each time will keep the grass growing vertically encouraging it to tiller and thicken.
Dull blades will tear the grass plant making your lawn susceptible to disease and dulling the colour. I regularly get asked to diagnose issues with prospective clients’ lawns where a lawn with a better colour is desired. It immediately becomes obvious that the mower being used to cut the lawn has dull blades. Sharpening or replacing the mower blades will instantly bring vigour back to the lawn.
I would recommend changing or sharpening your blades at least once every 6 months. It’s useful to have at least one spare mower blade in case you catch a root or buried object in the lawn, or if you don’t sharpen your own blades.
When watering an established lawn always water infrequently and deeply, ideally 1/2 inch (12.5 mm) of water needs to be applied in each area of lawn every watering.
How to measure the time required to apply 1/2 inch of water when using sprinklers
- Use flat bottom and straight sided containers, such as tuna cans
- Spread the tuna cans or containers in 4 or 5 random spots at least 1 meter away from the sprinkler.
- Water the lawn for 6 minutes
- Measure the depth, in millimetres, of water in each container
- Add together the depths in millimetres from each container, this is the total depth
- Divide the total depth by the number of containers
- Multiply the resulting number by 10
- This gives the number of millimetres of water applied in an hour by your sprinkler(s)
Repeat this method to check your sprinklers’ mm/per hour output annually
- Water the lawn area for 6 minutes
- (Container 1) 2 mm + (Container 2) 3 mm + (Container 3) 2 mm + (Container 4) 3 mm + (Container 5) 2 mm = total of 12 mm
- 12 mm (total depth collected in 6 minutes) / 5 (number of containers) = 2.4
- 2.4 x 10 = 24 mm of water output in an hour
For this example the lawn will need to be watered for 30 mins in each area to apply nearly 1/2 inch (12.5 mm) of water.
Soak the lawn infrequently
It is better to allow your lawn to dry out and show signs of dormancy than to over water a lawn. Avoid watering your lawn lightly every day or two as this will lead to the spread of moss and pearlwort as well as the production of a shallow rooting system. Watering must never be used to merely dampen the surface of an established lawn – this will do more harm than good on the long term.
Let the lawn dry out to some extent between watering so as to let the air in and to stimulate deep root development. However, do consider soaking some areas near fences, drives, window reflections etc by hand during dry hot weather every few days, these spots will dry out faster.
How often to water your lawn
How often depends on a number of factors including the soil composition, root system, grass type, amount of shade, weather conditions, to name a few, but as a simple guide when the weather is dry you can follow this watering guide:
- Once a week under ordinary dry conditions
- Twice a week in hot weather or with free-draining soil
- Once every 10 days in cooler, dry weather
When to water your lawn
- Ideally water in the very early hours of the morning or late in the evening, this will allow time for the water soak into the profile
- Don’t water an established lawn in the heat of the day, a lot of water will be lost to evaporation
- Watering during the heat of the day will not scorch an established lawn only waste water
Signs of drought stress
- Footprints stay in the grass
- Grass starts to look blue
- Then grey
- Then finally brown
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