It can be difficult to judge how short you should cut your grass. You’ll want it to look nice no doubt, with many, perhaps yourself, idolising a bowls lawn or a golf green style. This simply may not be possible, with lots of factors dictating the height of cut. What you may be surprised to hear is that it can be beneficial to cut your grass at a longer length to promote its overall health. Obviously, you won’t want the lawn to look overgrown, but there is a balance to strike between too short and too long.
How short and why?
The short answer (no pun intended) is really and truly however long you are willing to have it, because in terms of the health of the lawn, a longer cut is a better cut. The longer each blade of grass, the larger the surface area with which photosynthesis can occur. This means that the grass will get more of the nutrients that it needs to grow stronger and stave off any harmful disease.
A healthy blade of grass will be more durable, able to withstand greater stresses such as heat, drought and insect infestation. A denser lawn, which will naturally happen if you let a healthy lawn grow to a longer length, will also be more likely to crowd out weeds, as it is unlikely to find space to grow. Another benefit to having longer grass is the fact that you are less likely to have to use chemicals to rid your lawn of these weeds, resulting in a chemical-free lawn, which is always a positive.
In terms of exact measurements there is no perfect answer. However, a good guide for the average lawn would be to keep the length to something around the 2.5cm-4cm (1- 1.5 inches ) is probably a good balance, although if you are willing to keep it a little longer then up to twice that height certainly promote a healthy blade.
What happens if you cut it too short?
If you don’t allow your grass to grow, then the opposite of what we’ve just explained will happen. The shorter the blades, the less surface area there is for photosynthesis and healthy development to occur. Weeds are far more likely to appear if there are spaces on a thin lawn for weed seeds to germinate. When grass is short it will also suffer more from extreme cold and hot weather conditions because it hasn’t had the nutrients to be strong enough to withstand it.
Most domestic lawns do not have grasses that are suited to be mowed under 2cm so will likely struggle if cut below this height. Most golf bowling greens use very specific grass species designed to be mowed short which would be unsuitable and hard to maintain for a home gardener.
Cutting it to different heights throughout the year
Ideally, you’d want your lawn to be a consistent height throughout the calendar year. However, to get the most out of your lawn, there are some guidelines you should follow. A simple overview would be to raise, lower, raise, lower, raise.
At the beginning of the year exiting the winter period and heading into the spring, you should have your grass quite long, as long as you’re willing to keep it, to promote its health going into the next season. As the weather warms, through spring, keep it a little shorter. After the previous length it should look quite healthy at this point. Then, when it warms further into summer and there is less rain, then you’ll want to raise it again to maintain it properly.
As previously explained, the greater length and area to conduct photosynthesis should partially make up for the lack of water coming in during this time. Into the autumn where there is more moisture around, feel free to reduce the length of the grass again as there should be a better weather balance for the health of the grass. Finally, as you enter the winter months, raise the length again as they will need to be as strong as possible to withstand the harsher weather conditions.
This isn’t an exact formula, but a rough guide to protecting the state of your lawn.
How often should your lawn be cut?
A general rule of thumb to consider when thinking about how often to mow your lawn is the “one third” rule. When you are cutting your grass you should avoid cutting off more than a third of it at a time, so you should take this into consideration when deciding how tall you want your grass to be. If you plan to cut your grass to a length of 4cm, for example, then you should cut it when it has reached around 6cm, no later.
In the summer it will grow quicker, you may have to mow twice a week to stick to the one third rule. In the winter it will grow much slower so fortnightly mowing may be sufficient, so this is something you’ll just have to keep an eye on. On average, during early spring this could be roughly every two weeks, whereas in peak summer it could be up to twice weekly.