dethatching pros and cons

Pros and Cons of Dethatching Your Lawn

In Lawn & Garden by Jamie

Is your grass struggling to grow? Is it turning brown even when you regularly water it? Is there a thick layer of living and dead detritus swallowing up the grass blades?

Well, it might be time to dethatch your lawn.

What is Dethatching?

Firstly, thatch is the layer of living and dead grass shoots, stems, and roots that builds up between the grass blades and the soil. Dethatching is removing that layer of thatch to help your grass grow. When thatch grows more than ½” thick, it can suffocate your grass, preventing moisture from reaching the soil and preventing the grass from getting enough sunlight.

thatch layer location

The Pros of Dethatching Your Lawn

  • Helps water, nutrients, and oxygen to penetrate the soil, which your grass needs to live.
  • Reduces fungal diseases in your grass by preventing the anaerobic conditions in which fungal disease thrives.
  • Reduces pest pressure as pests can’t inhabit and eat the thatch.
  • Allows compost to reach the soil where the soil microbiology can break it down to feed the grass.
  • Removes dead grass.
  • Allows new grass seed to reach the soil to germinate.

The Cons of Dethatching Your Lawn

  • Thatch that’s less than ½” thick actually helps your lawn as both a mulch and a compost. The mulch keeps your grass shaded so you need to water less, and the beneficial microbes and worms in the soil will break down the thatch into nutrients that benefit your grass which means less fertiliser needed.
  • Dethatching stresses out your lawn as it will cut the grass. Done at the wrong time of year, when the grass is dormant, heat-stressed, or slowly growing, or when the soil is too dry or too wet, you can seriously damage or kill your lawn.
  • If the soil is compacted and the thatch is in the grey zone of dethatching (between ½” and 1”), then core aeration is a better bet. Core aeration will ease the compaction and remove some thatch for you. (Don’t use a spiked device, as it’ll compact the soil around the hole.)
  • Dethatching can be labour intensive or expensive, depending on your method. You can dethatch with a rake (if you have a small lawn) or by renting a power rake/dethatcher (if you have a bigger lawn or a lot of thatch). The power rake will run you between $70 – $100 to rent for a half or full day.

Do You Really Need to Dethatch Your Lawn?

You don’t need to dethatch your lawn if:

  • The layer of thatch is ½” thick, as it benefits your lawn by providing mulch and organic matter.
  • Soil compaction is the root cause of your lawn’s stunted growth. In that case, you’ll want to aerate your lawn. Wondering if you should aerate or dethatch? Read our article “What is The Difference Between Dethatching and Aerating?”.

You DO need to dethatch your lawn if:

  • The thatch layer is more than ½” thick, as the mats of slowly decaying thatch will create mats and anaerobic conditions where fungal disease and lawn pests thrive.
  • You plan to overseed or add compost and the thatch layer is preventing the seed or compost from reaching the soil.

Can You Prevent Thatch Buildup?

Excessive thatch buildup is not a natural phenomenon. In the long run, by addressing the root causes and switching over to organic lawn care methods, you’ll not only never have to dethatch again and your lawn will be a lot healthier and easier to take care.

Tip 1: Use compost instead of synthetic nitrogen

Synthetic nitrogen creates thatch by 1) causing grass to grow too fast, creating more root and leaf build up as a byproduct and 2) destroying the beneficial microbes in the soil that would otherwise break thatch down into nutrients your grass would benefit from.

The solution is to switch to compost for your fertilization needs. You can still grow beautiful, lush grass but the lower amounts of nitrogen in compost will mean your grass won’t burn and won’t grow as fast. This also means you’re free from excessive mowing! Woo hoo!

Compost also supports beneficial microbes by adding organic matter into your soil that the microbes digest into usable nutrients. This means your soil becomes healthier, the beneficial microbes decay thatch before it becomes a problem, and your grass is healthier in the long run.

Compost also has other benefits for your lawn. To learn how to switch over, check out our guide on how to add more organic matter to your lawn.

Tip 2: Seed with grasses less prone to thatch

Certain grass species and cultivars are more prone to thatch than others. Kentucky bluegrass, creeping red fescue, and creeping bentgrass form thatch faster than other species. Stoloniferous grasses, where the grass spreads by overground roots, also contribute to more thatch.

Other grasses produce less thatch, like perennial ryegrass and tall fescue. Overseeding these grass species will reduce the amount of thatch being produced. They’re less aggressive growers, but they’re hardier, lower maintenance grasses that will seriously cut down on the amount of lawn care you need to do.

Is There a Good Time of Year to Dethatch Your Lawn?

The best time of year to dethatch your lawn is when it is growing most vigorously and the soil is moist, as dethatching can leave your lawn looking ragged and your grass stressed.

For cool-season grasses, that means spring or autumn.

For warm-season, that means during the heat of summer.

What’s the Verdict, Should I Dethatch My Lawn?

If your lawn is building up a thick layer of thatch, and your lawn is at its height of the growing season, you should dethatch your lawn.

If there’s only a small layer of thatch through which oxygen and water easily move, then don’t. You’ll stress out your lawn for no reason.