when to scarify lawn

When To Scarify Grass? (And Step By Step Guide)

Sometimes you have to be cruel to be kind. If your lawn is choking on thatch buildup, ripping out the dead material will let the remaining grass breathe freely. In this article, we’ll explain the process of scarification and how it can benefit your lawn – and how to avoid complications.

Scarification is raking your lawn deeply enough to pull thatch and moss out of the turf. A normal rake is fine for small spaces, but larger yards call for a specialized machine. Scarification is typically done annually in spring or autumn. Rake up and discard the exposed thatch; overseed bare patches.

Overview of Scarification

Thatch is a layer of dead organic material that naturally accumulates as your lawn grows. It forms a layer under the grass blades. Walking on heavily thatched turf feels like walking on a sponge.

Scarification is a process that removes your lawn’s underlying blanket of dead grass, moss, mold, and weed seeds. The process also improves the texture and health of your lawn.

Rakes and other tools for scarification have tines that dig into the thatch and bring it to the surface. The amount of material pulled up may surprise you! The exposed thatch is composted or bagged for disposal.

After scarification is an ideal time to overseed thin areas on your lawn. With the thatch layer gone, seeds will have access to light, air, and moisture. The grass will be primed to fill in bare spots.

Scarifying benefits your lawn in the long term, but note that your turf may look a bit ragged until it recovers. It’s best done annually in the spring or fall when the weather is favorable.

What is Thatch?

Over time, your lawn’s grass naturally acquires a layer of dead material between its roots and top blades called thatch. It’s made of dead roots, stems, runners, and leaves that haven’t yet decomposed, along with other unwanted organic material like moss and weed seeds.

A light accumulation of thatch is natural and benefits the grass. It helps insulate the turf’s roots and keep the soil moist. It cuts down on weeds. As long as the thatch layer remains a half-inch or less, water and nutrients can still pass easily to the soil below.

Different grass species produce more or less thatch. Well-maintained, warm-season grasses are prime candidates for developing excess thatch. Ryegrass isn’t a heavy thatch producer.

Ironically, a heavy thatch layer that chokes its own grass is often a product of a lawn’s success. Soil microbes are unable to break down old material fast enough to keep up with rapid growth. Fertilizers and other synthetics can weaken the microbial population; improper watering – too little or too much – can also contribute to the problem.

How Does Scarification Work?

Scarification removes overgrown thatch to let water, air, and nutrients penetrate the soil. It’s done with a tool that digs into the matted material and pulls it from the lawn.

The tool can be as simple as a rake or involved as a professional heavy-duty machine. Manual raking is fine for small plots and there are various automated tools, but it’s best to purchase or rent a machine if you have a substantial area to cover.

The pulled-up thatch is deposited on top of the lawn. From there, it’s easy to remove.

Defining Terms

What’s the difference between scarification and raking, dethatching, or aerating?

Dethatching – Exact definitions vary, but dethatching is basically another word for scarification.

Raking – The usual purpose of raking is to collect debris from the lawn, but you can dethatch grass with a rake, too – scarification machines are essentially power-raking the grass. Push the tines into the turf and pull out the thatch. It’s hard work but does the job.

Aerating – Aeration and scarification are separate but complimentary lawn practices. Aeration pulls small cylindrical pellets from the soil. It helps loosen compacted ground and open it to nutrients and air.

Why You Should Scarify Your Lawn

Scarification is about improving your lawn’s soil and growing conditions, because good soil means happy roots and thriving turf.

Dense, fast-growing lawns usually need annual scarification. They produce so much thatch, it outstrips natural decay. Thin lawns without thatch overgrowth don’t need scarification and shouldn’t have it.

What If You Don’t Do It?

An excess of thatch doesn’t so much kill your lawn outright as slowly strangle it.  Lawns in desperate need of scarification often develop a yellow cast and dry patches.

Heavy thatch can deprive the soil of air and moisture: the result is struggling grass with stunted roots. The problem can sneak up as your lawn gradually stagnates and becomes thin and patchy.

When Should You Scarify?

The best time to scarify your lawn is spring or early fall when the grass is growing robustly.

Scarification is a rigorous process, and your lawn will need a few weeks of good growing conditions to make a recovery. Planning is so important! Exposing a recently scarified lawn to hot summer or cold winter weather can cause it serious damage.

How To Scarify Your Lawn

Scarification is not complicated, but it’s important to do it right. If done incorrectly, the process can set a lawn back instead of helping it.

There are three phases to scarification: planning, scarifying, and aftercare.

Phase 1: Planning Ahead

Scarification requires planning to avoid trouble. Thinking it through also makes the job easier.

Know Your Thatch

The first thing to do is determine how much thatch you have. A metal core sampler is ideal for checking the depth of the thatch; making a square divot with a trowel works too. Dig down at least two inches.

Scarification is only beneficial if the thatch layer exceeds a half-inch thick. If you haven’t thatched for some time – or ever – the dead, straw-like layer may be more than an inch thick.


The exact tool you need depends upon the size of the lawn you’re scarifying:

Hand Rake – Your garden rake is great for small areas. It makes an excellent scarifier; just push the tines down and rake out the dead stuff.

Electric Rake – There’s no official type of electric scarifying rake; instead, a huge number of variations exist. A good one can make the job easier for medium-sized yards.

Scarifying Machine – For sizeable lawns, a machine becomes necessary. The typical scarifier is pushed like a lawnmower. Its metal blades cut vertically into the soil to grab the thatch and pull it out onto the lawn. There’s a lot of variety within the category, from lighter retail models to heavy-duty professional machines.

Check the Weather

You want the lawn to repair itself quickly, and for that you need the help of Mother Nature. Check the forecast! Warm, humid conditions are best for scarifying.

The best time of year for scarification coincides with ideal grass-growing weather in spring or autumn: bright with mildly warm temperatures and moderate, periodic rain. Choose a period with nice days both before and after your goal date.


Spring is usually the best time to scarify grass. It gives the turf a long growing season to completely recover before the rigors of winter. Spring is also the best time to scarify a shady lawn that thins during winter and grows thicker in the warm months.


Autumn is the best time for scarifying heavily thatched lawns: it’s the ideal time for overseeding. Fall scarification also helps reduce weed seeds.

Phase 2: Scarifying Step-by-Step

Preparing the Lawn

The lawn should be in good shape before you scarify. It shouldn’t be dormant or parched or sodden; if necessary, wait until conditions are right.

Here are tips to getting the turf ready:

  • The lawn should be dry to walk on but slightly moist. Depending upon the weather, watering a day or two ahead can produce the right conditions.
  • Try to remove as many weeds as possible from the lawn to prevent them from spreading and reduce the debris load.
  • (Optional) Some lawn-owners take steps to kill their moss a few weeks ahead of scarification.  The sad news is, they’ve probably already spread. If you’re going the chemical route, treating the lawn to kill moss <em>after </em>scarification makes more sense.
  • The lawn should be cut short before scarification to avoid pulling up long grass and to reduce debris. Bring the grass height down gradually in the weeks before go-time to avoid shock. Cut at the lowest acceptable setting just before scarifying.
  • If you usually leave your mowed clippings on the lawn, make an exception. Put on the exhaust bag or rake up the cuttings. You don’t want to deal with the messy extra material.
  • If you’re using a scarifying machine, adjust the tines to just slightly nick the soil about a tenth of an inch (2 to 3 mm) deep. More severe scouring than this can damage grass roots.
  • If the thatch is thick, raise the blades higher on the first pass or two and gradually lower them.

Making the Cut

Scarifying uses the same methodical pattern as mowing does. Go up and back in even rows to cover the whole lawn. Two complete passes are typically made, with cleanup after each one.

First Pass: With either a rake or scarifying machine, outline the borders first, and then establish the lines to follow. Scarify each part of the lawn. Start with a light touch and go deeper in subsequent passes.

Your lawn will look progressively worse from this point, but don’t be discouraged. It’s only temporary. After you’ve completed a pass of the whole yard, rake up the thatch debris and bag or compost it.

Second Pass: If you’re using a machine, make a second pass at a different angle than the first. Cutting in a different direction pulls out the remaining thatch more effectively. If the grass looks a bit tattered, take it easy by using a tight angle (maximum disruption is caused by scarifying in a line perpendicular to the original).

Additional Cuts: Average lawns will probably have had enough after two rounds, but heavily matted turf may benefit from extra passes. If the thatch is very thick, make the first pass shallow; gradually extend the blades deeper in additional rounds until they barely graze the ground.

Heavy Scarification

If your lawn is choked with thatch, it’s generally good to make several passes and follow up by overseeding. Remember that the more scarification you do, the riskier it is – too many passes and you’ll have to reseed the whole lawn.

Don’t be too extreme in one session. It often takes a few seasons to fully dethatch a highly matted lawn.

Phase 3: Lawn Aftercare

Scarfication doesn’t offer the immediate satisfaction of a nicely mowed or raked yard. Your lawn will probably look terrible. Some grass may have been pulled up with the thatch and bare spots might have been revealed. On the plus side, you might notice that the lawn grass looks finer and more level.

Scarifying does some damage, but don’t worry. As long as you’ve kept the blades from digging into the soil, the roots will be unharmed. The broken turf quickly repairs itself if growing conditions are good.

Tips to revive your scarified lawn:

  • Help start the healing process with an immediate watering.
  • Fertilize a few days after scarification with a high-potassium, low-nitrogen blend. The dethatched soil will be ready to assimilate it.
  • Reseed thin or bare patches.

When NOT To Scarify Your Lawn

Scarification is only needed if your lawn has excess thatch, and it should only be done at the proper time. In general, you should only scarify your lawn once a year.

Here are some scenarios when scarifying your grass would be counterproductive:

  • Grass that isn’t matted with thatch doesn’t need to be scarified! Thin lawns don’t produce an overabundance of thatch; unnecessary scarifying is more likely to weaken a lawn than help it.
  • A struggling lawn shouldn’t be subjected to scarification. Get it healthy first. Weak lawns don’t recover as quickly – or at all.
  • Scarification can damage fledgling turf if your lawn is new and hasn’t had time to establish itself.

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