Maintaining that perfect looking lawn can be a lot of work, and even the most careful lawn guru can end up with a bald patch here and there.
If you are looking to fill in some grass-free areas in your lawn, you are probably wondering: does cutting grass make it spread?
The answer depends on the type of grass you have on your lawn. Grasses that are well suited to colder climates do not tend to spread a lot, whereas grasses used in warmer climates can spread. The height of the blades will affect how this happens.
Does grass spread on its own?
Some grasses do spread well on their own. These are warm-climate grasses such as St. Augustine, Bermuda, centipede, and zoysia.
Cool-climate grasses will spread less effectively; these are species such as rye and fescue.
The first thing you need to do is figure out which type of grass you have on your lawn.
There are a few ways that grass spreads on its own.
Seeding
The first method is seeding. Seeding is when the grass plant produces seeds. For most species, this requires growing to a length that is not desirable for lawns. However, some grasses have adapted to grow seeds at lower heights closer to the root.
With all the grass hybrids being used, there is no guarantee that the seeds your lawn produces will be fertile and lead to new grass growth. In short, do not rely on this method of spread to get a lush, full-looking lawn.
Tillering
Tillering is another method that some grasses use to spread. Tillers are a new shoot (or stem) that will grow blades (these are the grass leaves). Grasses that use method are sometimes called clump grasses or bunchgrasses.
This method can make the lawn look thicker, but to actually fill in a bare spot of any size would take quite a bit of time. Perennial ryegrass and tall fescue are examples of bunchgrasses.
Rhizomes
Rhizomes are a third method of spread that some grasses will utilize. This is where a runner shoots out underground, travels away from the mother plant, and starts a whole new plant.
The runners can travel a long way to find a bare spot to populate. Warning, this can also include any nearby flowerbeds!
Most grasses that use rhizomes to spread, also use tillers to thicken. These include Kentucky bluegrass and fine fescue.
Stolons
Stolons are similar to rhizomes, but instead of running underground, they run above ground. They can go short or long distances to find an open area to start new grass plants in. They can form multiple new plants along their length.
Creeping bentgrass, St. Augustine, and zoysia use stolons to spread. They will do so rapidly if the soil is easy for the new plant’s roots to penetrate. They can even work their way through other grass types and take over a lawn.
Does cutting grass help it spread?
Ok, so some grass types can spread by various methods. Now the question is, does cutting grass help it spread?
Yes, cutting grass can both thicken a lawn and help it spread depending on the type of grass it is.
If your grass type utilizes tillering, properly cutting it can help the lawn thicken.
If your grass uses runners (either above ground or below), then proper mowing can help the grass spread to bare spots.
Grasses use the same process most plants use to make food, photosynthesis. This takes place in the blades (the leaves) of the grass plant. The blades are the part you are cutting when you mow your lawn.
When you cut the blade of the grass, the plant now has reduced surface area to absorb sunlight. The response of the plant is to create more surface area on the blade.
Cutting your grass to about 2 inches will help promote runner and blade growth. Cutting shorter than this will cause the plant to focus only on blade growth.
You want both parts of the plant to grow. If you only get blade growth from the exiting grass plants, then your grass will not spread.
Cutting too short can also lead to an underdeveloped root system as the plant puts all of its energy into blade growth. A weak root system means your lawn will not be able to support the existing grass plants, let alone spread!
Once you have cut your grass, you want to give it some water and some fertilizer. Both of these provide your lawn with the resources it needs to produce food using photosynthesis.
How Often Should I Cut My Grass?
This will be determined by the height of the grass rather than a set amount of time. To promote the spread of grass, you definitely do not want to cut the grass below that 2-inch height previously mentioned.
For a grass like Bermuda, you want to cut all the way down to the 2-inch mark to encourage spread through runners.
For grasses like St. Augustine and centipede, you want to cut them on the higher side to promote runner growth. Set your mower to cut the blades to about 2 ½ to 3 inches.
After you have cut, watered, and fertilized your lawn, you want to let it recover from the process. Remember that you have essentially just cut off a part of the plant that is used to make food. The mowing process is stressful for the plant, and it needs to grow and recover.
Let your grass grow and recover, but do not let it grow past about 4-inches. Once it reaches this height, the grass thatch will become very thick and will stop water from getting down to the soil and roots.
Of course, grass at that height will also look unruly and will take your lawn from a manicured masterpiece to an unsightly mess!
If you can, it is also best to mow just after the hottest part of the day or early in the morning. Mowing is already stressful on the grass; blazing heat is an added stress that your lawn doesn’t need post-mow.
Following these mowing tips will give your grass the best chance to spread and thicken.
Will grass spread to bare spots?
Yes, warm climate grass will spread to bare spots if they are a species that can produce runners. These are species that either make stolons (above ground runners) or rhizomes (below ground runners). Only grasses that thrive in warmer environments produce runners.
If you live in a warmer climate that sees summer temperatures of 27 to 30 °C (80 to 95°F), you can get the warm climate grasses that utilize runners to create new grass plants.
If you live in a cold climate, these grasses are not a good option because they will go dormant and turn brown at temperatures below 10 °C (50 °F). This can leave you with a brown lawn before you are ready to tuck inside for the winter!
There are several kinds of warm-climate grasses, and each type has several different species. Below is a list of some common examples:
- Bermuda
- St. Augustine
- Zoysia
- Buffalo
- Centipede
- Bahia
Seeding
Whether you have warm- or cool-climate grass, the best way to cover bare spots in your lawn is to use a bit of grass seed and some hay or wood mulch.
- Cover the bare spot with grass seed and push it down a small way into the soil.
- Fertilize and water the patch, then cover it with the hay or Peat Moss. Peat Moss works far better at stopping birds from eating the seeds.
- Don’t forget to keep the seeds moist while they are beginning to germinate (grow), but do not flood them with excessive water either.
It can take your grass up to 21 days to germinate, so do not worry if you don’t see any blades popping up in the first few weeks.
The Last Straw
Warm-climate grass can spread to bare spots by sending out runners either on top of the soil or underneath it. Most Cool climate grasses do not have this capability.
Either way, the best way to cover bare spots in your lawn is to seed them.