Everyone loves a healthy lawn and we often think of our lawn as one big green (hopefully) organism but I find it helpful to think of it as a community of individual plants. Each plant has roots, a stem and a canopy and the proper pruning of that canopy, aka proper mowing of the grass blades, can have a major impact on the health of that plant. A properly mowed lawn will be healthier, more low-maintenance, more drought resistant and will even naturally have less weeds.
The correct mowing height depends on the types of grass you have in your lawn. Most lawns have one main variety of grass with smatterings of secondary varieties here and there. It is best to pick the proper height that corresponds to the main variety in your lawn. This will not only weaken the secondary varieties but strengthen the main one. Part of the way this happens is due to the fact that there is a direct correlation between the length of the grass blade and the length of the roots. Simply put, the longer the grass blade, the longer the root. If you maintain your grass at its maximum healthy height then it will have a deeper root system which will allow the grass better access to water and nutrients. A longer root system can become critical to a healthy lawn during the hot summer months when the water is quickly evaporated out of the top couple inches of soil. The chart below is of the main types of turf grass in our area and their recommended mowing ranges.
Proper mowing height will also give the grass a leg up when pushing out unwanted weeds. As with pruning any woody plant, new shoots are encouraged to grow when you prune off (or mow off) the tips of a branch (aka grass blade). This “pruning” then creates a lush canopy of grass blades interlock to shade the soil beneath it, preventing many weed seeds from germinating.
|Grass Type||Recommended Height (in)|
|Cool-season Grasses||Fine fescue||0.5-3|
It is best to not mow off any more than 1/3 of the grass blade at any given time. The main reason for this is that it prevents you from cutting into the stem of each grass plant. Cutting into the stem will shock the plant and cause it to be stunted for a while. This is because when the stem of the grass is cut it means you have removed the major producer of chlorophyll (food factories) for the plant. Now the plant has to move enough chlorophyll into the stem in order to produce enough food for the grass to be able to grow again. This takes time and until it has moved/ created enough chlorophyll it will be stunted. Another reason for mowing only 1/3 off at a time is that the pieces you cut off will be smaller and mostly water so they will quickly disintegrate back into the lawn.
A good way to say it is that we recommend you mow according to the height of the grass as opposed to mowing by the day of the week. For example, if you are trying to maintain your lawn at a 3 inch height you would mow it when it reaches 4 inches tall. In all practicality this means that you will be mowing more often in the spring and fall when water is plentiful and grass is growing vigorously and less often in the hot summer months. Mowing at the maximum healthy height will also mean you mow less often. The chart below shows that the shorter you want to maintain your lawn the more often you will have to mow if you do not want to cut into the grass stems and shock your plants.
|Desired Height||Mowing Height||Inches Of Growth Removed|
Additional Mowing Tips
- Maintain a sharp blade, sharp blades make a clean cut whereas dull blades will tear and leave grass tips shredded and browning.
- Mow when the grass is dry. Wet grass/ clippings will mat and cut unevenly.
- Mow in different directions. Lawns are living plants and will start to “lean” in the direction you mow if you do not change it up. By doing this each plant will grow straight and tall.
- It can be beneficial to mulch leaf debris into your lawn in the fall. The key is to mulch the leaves with your mower when they are dry and go over them several times