The welcome rain during this last week will have our lawns in Central Kansas growing quickly and how you mow your lawn will play a big role in determining its fate. Will your lawn stay healthy and weed free or will it struggle and invite the weeds to invade? Here is why how you mow is so critical to your lawn’s health.
The leaves of your turf are the solar panels that provide the resources for growth to the crown and roots of each turf plant. With this in mind, how we manage these solar panels becomes very important for our lawn’s success.
Mowing too low places turf under great stress and leads to the need for excessive watering. If done repeatedly, short mowing (scalping) produces thin, weak turf that is highly susceptible to weeds. Always avoid a drastic or sudden reduction in cutting height, which seriously diminishes turf root growth.
In general it is best to mow tall. But the definition of tall varies depending on the type of grass you are growing.
Recommended mowing heights for lawns
Bermudagrass: 1–2 inches
Bluegrass: 3-3.5 inches
Buffalograss: 2.5–4 inches
Tall fescue: 3-4 inches
Zoysiagrass: 1–2 inches
Tolerance to short mowing ranked best to least
Fequency: 1/3 Rule
In the best case scenario we would never remove more than 1/3 of the turf leaf blade at one time. Following this rule will allow enough leaf surface to remain and not interfere with the energy balance of the turf plant. Failure to follow this guideline will lead to excessive removal of leaf tissue (solar panels), which shocks the grass and results in thin, stemmy turf with a poor root system.
This means that a tall fescue lawn would normally be mowed to 3 inches high as soon as the turf is around 4.5 inches tall. Thus the timing for mowing your lawn will depend on it’s growth. You may find you need to mow every 4-5 days in the cooler spring but only every 2 or 3 weeks in a hot or stressful summer.
Here’s a tip: taller mowing also means less frequent mowing. The shorter a lawn is cut, the more frequently it must be cut (think about greens on a golf course). If you want to mow less, mow at the heights recommended above for your particular grass.
|Height of cut||Mow when turf reaches||Growth between mowings|
Keep weeds out
Mowing at the correct height helps keep weeds out. Research has proven that maintaining a lawn at the correct height will dramatically reduce weed pressure since the turf leaf blades shade the soil to keep off sunlight which triggers weed seed germination. The healthy and vigorous turf is your best defense against weeds. Check out some research here.
Let clippings fall: There is no need to collect clippings from the lawn if you follow the 1/3 rule above. The short clippings will quickly shrivel down into the turf canopy. Mulching mowers are wonderful for dealing with clippings but don’t work as well on excessively tall turf or wet grass. It is a misconception that leaving the clippings leads to thatch. Clippings are 85 to 90 percent water and shrink and decompose rapidly. Clippings are also a source of nitrogen for the lawn which means that if you leave them you can use 25% less fertilizer each year.
Mowing when wet: It is always best to mow when dry to avoid wet clippings staining buildings, concrete etc… but during rainy weather it is better (if possible) to mow slightly wet grass at the right height than to let grass grow excessively tall and then scalp it.
Mowing pattern: Change it up! Alternate the mowing direction to avoid soil compaction in one spot and to prevent grass from constantly leaning over in one direction.
Sharp blade: A sharp mower blade is critical to keeping turf in good health. A dull blade shreds the leaves which opens up more surface area for moisture loss and disease entry into the plant. It is best to sharpen mower blades about every 10 hours of mower use.