The best time to scarify your lawn is either in mid-spring when warm-season grass begins to grow strongly, or in autumn when cool-season grass is experiencing a late-season growth spurt. The optimal timing depends on whether your lawn is planted with warm-season grass or cool-season grass.
It’s important to only scarify your lawn when your grass is actively growing, as the scarifying process removes a lot of dead grass and material, leaving bare soil. If grass doesn’t fill in this bare soil, weeds may invade. For this reason, never scarify dormant grass. Also, avoid scarifying in the height of summer, when grass growth slows.
Best Time to Scarify a Lawn
Scarifying your lawn, also called dethatching or vertical mowing, is the process of using a specialized tool or mower to remove dead grass, weeds, and thatch from your yard. When performed at the right time, this results in a thicker, healthier yard, that is far greener than before. Below are guides on when to scarify, and how often, based on your location.
United States
In the United States, the best time to scarify grass is either spring or fall. The optimal season depends on your grass type and region.
Spring
- Best if your lawn is planted with warm-season grass (Bermuda, St. Augustine, etc.)
- The optimal time to scarify in warm Southern and Coastal regions.
- Wait until the grass has completely exited winter dormancy and is growing strongly (at the point where it requires weekly mowing).
- Consider overseeding after scarifying. This will promote a thicker lawn and prevent weed invasion.
Fall
- Best if your lawn is planted with cool-season grass (fescue, bluegrass, etc.)
- Preferred time to scarify in Northern and Midwestern states.
- Wait until summer temperatures have cooled and grass has begun fall growth spurt.
- After scarifying a cool-season grass, overseed for best results.
Canada
Because most regions of Canada are planted with cool-season turfgrasses that experience their strongest growth in fall, the best time to scarify your lawn in Canada is in late summer through early fall (late August through early October).
When scarifying in the fall, you can use aggressive scarifying tools to remove thatch, moss, and dead weeds from your yard and provide the best opportunity for your lawn to recover and fill in any bare soil. Your cool-season grass performs best in the fall. In a short time after scarification, your lawn will look better than ever.
United Kingdom
Much like the US, the best time to scarify your grass in the UK is either during spring or fall. Your grass will recover well from scarification during either of these seasons.
Spring scarification in the UK is best performed in mid-April through early May. Use a rake or light scarifying tool. You can remove thatch this way and still maintain a thick enough yard to resist an invasion of spring weeds.
The best time to scarify your UK lawn in the fall is between early September and mid-October. Feel free to use heavier scarifying methods at this time to aggressively remove thatch buildup, as your grass will be growing strongly and less at risk from weed invasion.
Australia
Like the US, the best time to scarify grass in Australia depends on the type of turfgrass you have, as well as the season. Here is a quick breakdown:
September–October
- Best time to scarify cool-season grasses (rye, fescue, etc.).
- Ensure your grass has begun growing strongly again (at least 2 cm per week) following a warm-weather lull or semi-dormancy.
October–December
- Best time to scarify warm-season grasses (Couch turf, Buffalo grass, etc.).
- Ensure your grass has completely exited dormancy before scarifying.
- Wait until the grass is growing strongly (at least 2 cm per week).
Should You Scarify Before or After Cutting Grass?
Mow your lawn before scarifying. This will allow your scarifying tools to be most effective and create the best conditions for grass growth after scarification.
Before scarifying, mow your lawn at a relatively low setting, about 1 inch in height (2.5 cm). This will cut the grass low without killing it or scalping your lawn. If your grass is left too long, your scarifier will struggle to remove thatch effectively, resulting in wasted time and effort.
Can You Scarify Your Lawn When It’s Wet?
Do not scarify your grass when it’s wet. It’s best to wait 1–2 days after rainfall or watering before scarifying. It’s acceptable for soil to be cool and moist to the touch, but it should not be wet. Similarly, there should be no moisture on the grass blades.
By scarifying in dry conditions, you will get the best results and reduce damage to your yard. Scarifying a wet yard can severely damage grass and result in a very unsightly lawn.
How Many Times Should You Scarify a Year?
You can scarify as often as 1 time per year or as seldom as once every 2–4 years. Generally speaking, if performed on a yearly basis, scarification is an easy process because there is little thatch buildup. Regular scarification will also maintain your lawn’s pristine appearance.
The longer you wait before scarifying your lawn, the more thatch and organic material will build up, resulting in a lot more work when you do scarify. In the meantime, your lawn will also grow more unsightly and your grass may be weakened by thatch and buildup of dead organic material.
Does Scarifying Aerate the Lawn?
Scarifying does not aerate your lawn. The goal of scarification is to remove thatch that rests on top of the soil. That buildup steals water from your lawn and prevents new grass growth. A scarifier removes thatch from your lawn but does not penetrate the soil deeply.
Aeration, on the other hand, penetrates the soil 1–6 (2.5–15 cm) inches in depth. This helps break up compacted soil, allowing for healthy root growth, as well as allowing nutrients, water, and oxygen to enter the soil.
The perfect time to aerate is right after you’ve scarified your lawn. The two processes are different but work hand-in-hand to promote healthier grass.
When Do You Scarify a Lawn?
The optimal time to scarify your lawn depends on your grass type and region.
- If you are cultivating warm-season grasses in the Southern United States or warm regions of Australia, spring is the best time to scarify your lawn, because your lawn will take advantage of the process and grow thickly in warm summer months.
- If you are cultivating cold-season grasses in the Northern United States, Canada, or most parts of the UK, fall is the optimal time to scarify your lawn. Your grass has its strongest growth spurt in the fall months, which will allow it to reclaim soil laid bare by scarification.
Scarifying your lawn will remove the dead thatch, moss, and wilted weeds that are choking out your grass. After you’ve scarified your lawn, your grass will have a greater ability to gather water and nutrients and grow unobstructed, more beautifully than ever.