After mowing and throughout different seasons, your lawn will accumulate a layer of dead grass, stems and roots between your live grass blades and the ground. Some thatch, less than half an inch, can be good for the soil because it can protect your grass from extreme temperatures and hold in moisture that will feed your lawn. However, if the thatch layer is more than half an inch, it can begin to suffocate your lawn by blocking access to oxygen and water. It can also provide a home for pests and insects, as well as reduce the impact of pest control products. Once your lawn develops a larger layer of thatch it is time to dethatch and refresh your lawn.
Dethatching is the process of using equipment with tines or blades designed to slash into your thatch and pull it up. You’re not pulling grass up by the root but cutting through overgrowth and opening soil that may have become hard or unnourished due to being covered for too long.
Dethatching removes the thick layer of decomposed grass, leaves and other dead plant material. Thick layers of thatch become a barrier, instead of a benefit, to the growth of your lawn. Breaking up the layer of thatch gives the soil access to air, water and fertilizer; and it allows your lawn to drain more effectively and evenly.
You don’t need to have dethatching on your to-do list every year. Typically, you should plan on dethatching every five years or so, but be mindful of the signs of thatch overgrowth to know when your specific lawn needs this type of care.
Ways to determine whether it is time to dethatch your lawn include walking on it to see if the ground is spongy or springy to the touch, noticing that your lawn has lost its green, healthy color; and seeing that it has developed an insect problem. You should also use a tool to check the thatch depth, or just your hand. Measure to see if the thatch appears to be three-quarters of an inch or more. That is when you know your lawn is ready.
When considering seasonality for dethatching, it is best to dethatch breeds of northern grass in late summer to early fall. For southern grasses, you should dethatch in late spring. This aligns for each region to when the grass is actively growing. You should also do your work when the ground is at least somewhat moist. This will make it much easier for the tines or blades to break the surface of the soil.
In warmer climates, zoysia and Bermuda grasses are prone to forming thatch; cool season grasses like Kentucky bluegrass, creeping red fescue, and bentgrass are more likely to require dethatching because they are bred for vigorous growth. Tall fescue or perennial ryegrass seldom have thatch problems because they are clump-forming grasses.
If your lawn has an excessively low soil pH or compacted soil, this can also make it more prone to thatch overgrowth.
If you have a smaller lawn with light to medium growth you may choose to manually dethatch. It is the most cost-efficient method but certainly the most labor intensive, as well. Manual dethatching rakes are heavier than a standard rake, with shorter tines and curved blades. These short-tined rakes are designed to dig into your lawn and pull up thatch as you rake. Just remember that you’re not trying to tear up all of your grass, just cut through the layer of thatch and break up your soil.
Other options available for larger lawns or heavier growth include power rakes and vertical mowers.
Power rakes are like a push mower, but they come equipped with rotating, rake-like tines that dig into thatch at the soil level to pull it up. Vertical mowers, also called verticutters, will slice through your thatch layer and into your soil with vertical blades. This heavier equipment pulls thatch—and often grass roots—to the surface as it goes. Verticutters are optimal when dealing with thick thatch layers on lawns in need of renovation. The blades adjust to control how much thatch you remove at once, and you should always start with the blades set higher for your first pass to make sure that it is not tearing up your lawn too much.
Whichever option works best for your lawn care needs, you should still do the same process to finish the job by raking up all the thatch debris and watering your dethatched lawn thoroughly.
While you probably hear about dethatching and lawn aeration in the same context of lawn care, they are two different processes. However, they can work together to help keep your lawn healthy because they both work to make sure your soil and grass are getting the proper amount of oxygen and moisture. Aeration removes small cores of soil, which does include the thatch layer, and creates open pores for water and nutrients to penetrate any compacted soil or thatch; whereas dethatching will slice through the thatch, into the soil, and remove the barrier of thick, accumulated plant matter. Interested in learning more about aeration? Learn How to Aerate Like a Pro.
Once you have dethatched your lawn, don’t be concerned that it looks a little ragged. Your first step of aftercare is to use a leaf rake to get rid of the thatch you loosened up. If you see bare spots created by dethatching, you can use a patching product to cover and repair them.
After your cleanup is a great time to seed your lawn, apply new turfgrass, and consider topdressing it with pieces or plugs of soil that are left.
It will most likely take about three to four weeks for the lawn to recover and show signs of new growth.
Adding dethatching to your lawn maintenance checklist means your lawn will be able to thrive and give you the healthiest, greenest lawn on the block.
Interested in knowing more about lawn dethatching? Speak with your local RDO Equipment Co. dealer to learn about everything from lawn equipment to lawn tractor attachments, utility vehicles and specialty equipment.