Scarification of a lawn is often used to revitalise and keep an existing lawn in check. Scarification involves using a machine, a bit like a lawnmower but much sharper, that has a rotating set of blades that slice down into the topsoil. This acts to both cut the grass rhizomes, drag out debris and furrow the soil.
Think of scarification as a yearly or bi-yearly step in lawn maintenance to help reduce the build-up of thatch, dead grass and help keep your lawn in top form. Watch my popular guide on how to easily scarify your lawn and read on for more detail of each step in the lawn scarification process.
- Why scarify a lawn?
- When to scarify a lawn
- What is lawn thatch?
- How to remove moss from a lawn
- How to scarify a lawn
- Overseeding a scarified lawn
- Why does my scarified lawn look a mess?
- When can I mow a scarified lawn?
Why scarify a lawn?
Lawn scarification is part of your essential lawn care routine if you want a lush green healthy lawn. Think of it as a form of lawn pruning.
Scarification can help improve your lawn by:
- Removing dead thatch and debris from the soil level
- Aerating the soil as it cuts into the surface
- Encouraging vigorous grass growth as it severs rhizomes causing the grass to send out new shoots
- Reduce compaction and encourage drainage
When to scarify a lawn?
The very best time to scarify a lawn is Autumn time ie Sept to late Oct in the UK.
Although you can scarify in spring you’re in a race against weed growth, whereas in autumn time the weeds are slowing down. You can also be more vigorous in your scarification in autumn than in spring.
You want to avoid scarifying in the following circumstances:
- During the middle of summer when the grass is growing quickly as it makes mowing very difficult for a few weeks post scarification
- When weeds are present or actively growing
- In a heatwave when the ground is very dry
- During a wet season when the ground is saturated
- Always wait a week or two after using systemic lawn weedkiller or moss killer
- Don’t scarify newly laid turf or a newly seeded lawn. Let them establish for at least a year or so first
- It may be obvious but this won’t work on artificial lawns (read why you really should reconsider fake grass)
What is thatch in a lawn?
Over time your lawn will build up what is called thatch. This is a layer of dead grass material, not dropped from mowing but as the grass dies back and newer shoots take their place. If you think of turf as a large matt of interconnected dead rhizomes and roots you can start to understand why after a period, it may become congested.
In a perfect world, the new grass and the breakdown of this thatch can be in perfect harmony. It’s usually fungi that break down thatch but if your grass outgrows this process, usually after a feed then thatch can build up causing a detrimental effect on your lawn.
You can tell too much thatch as if you get down close, you’ll see a brown webbed layer in between the grass, you can also feel the grass turning spongy when you walk on it.
Does scarifying remove moss?
A build-up of moss can also occur in your lawn which also feels spongy underfoot. Scarification is the best way, other than synthetic chemicals, to remove this and help keep your lawn in tip-top condition. Think of scarification like giving a muddy doormat a good shake, brush and wash to remove rubbish, matted strands and lift the pile.
Some gardeners may put a moss killer down like Iron sulphate before scarifying, it depends on just how mossy or bouncy your lawn is! I tend not to use it and save such treatments only for the worst mossy lawn offenders.
Scarification lifts moss easily from a lawn meaning it can be disposed of or composted. Helping the lawn breathe and preventing moss from outcompeting your beloved lawn seed!
How to scarify a lawn
Scarifying a lawn is no harder than using a lawnmower. What puts a lot of people off it the fact it feels and looks brutal. Not many people are open to slicing open their lawn, no matter how lumpy bumpy or ugly. However, this is the very process that your lawn needs to remove intruders such as moss and thatch.
Although your lawn may look awful directly after scarification, in about 3-4 weeks it should start to look far better than it did before as new shoots emerge. It’s well worth the leap of faith.
Step 1: Remove all weeds from the lawn:
Yes, this may be a time-consuming approach but it’s really necessary. If you don’t remove them then using the scarifier will only help propagate perennial weeds meaning they come back two-fold. I prefer to hand weed smaller lawns, not because I’m a sadist but I’m not a fan of chemical weedkillers.
However, for larger lawns, you may need to consider some form of selective weedkiller. (Always follow the instructions and use them with care).
Step 2. Mow your lawn short:
The next step is to then mow the lawn as short as possible without scalping it. Ie slicing up the top layer of soil. Scarifiers slice vertically whereas mower scalping slices horizontally damaging the grass. Start on a high setting and then work down until it’s short.
Step 3. Set the scarifier depth:
A scarifier should have a depth setting or adjuster. A bit like a lawnmower you can choose how deeply you scarify. For a seasonal light scarify then a higher setting is preferable. For a really poor lawn then a deeper setting is required. Use your judgement, you can always start higher and work lower based on how much debris comes out.
Step 4. Scarify either vertically or horizontally on the first pass:
Like you would do if you were mowing the lawn. Going from edge to edge slowly. Ensuring you empty the collection bin as soon as it is full. You may be surprised by how much comes out!
5. Scarify again at 45 degrees to the first pass:
This diagonal scarification ensures that the lawn is fully opened up and creates a criss-cross matrix pattern. It ensures even thick regrowth and aeration to the top layer of the turf.
6. Once fully scarified it is time to reseed:
If your lawns are in a bad way or you have an ornamental lawn it’s then time to overseed after scarifying. Again, this depends on how frequently you scarify and the condition of your lawn. With a poor lawn, I’d always overseed to help it along.
Scatter a fresh grass seed mix at 15-20 grams per square meter to help encourage additional grass growth.
Step 7. Water your lawn:
The final step is to thoroughly water the lawn. Your lawn is now in fight mode as its rhizomes start to send out new shoots. So water it well to help it on its recovery mode. Ensuring in dry spells that you water it twice a week for the first 2 weeks or so if need be.
8. Consider top dressing the lawn:
This really is an optional step for really poor lawns or dry areas. Your new grass seed will need moisture to germinate so sieving a layer of light compost over your lawn, not to completely cover but just lightly dress. This will help retain moisture and aid seedling germination.
Why does my scarified lawn look terrible?
There’s no denying that after scarifying your lawn will look terrible, horrendous or ruined. But please don’t panic. It will soon bounce back. You’ve removed years of dead moss, thatch, grass and debris. You’ve also sliced through all those grass rhizomes which will result in fresh soft grass growth.
However, you do need to give it time. In 4-6 weeks your lawn will already start to recover and it’s definitely worth the wait. So if your newly scarified lawn looks terrible that’s normal and it will recover.
When can I mow my lawn after scarification?
Your freshly scarified lawn will take between 4-6 weeks to start showing thick new growth. You can mow the scarified lawn about 2-3 weeks after scarification. Keep the setting high though to help encourage the new growth.
Scarification is a brilliant way to reinvigorate lacklustre or compacted turf. With a little bit of effort, even the worst offending lawns can be revived. Scarification removes, moss, debris, thatch and helps open up your lawn. Once you get over the awkward and brutal aftermath its a worth lawn maintenance activity. Within 4-6 weeks, your lawn will bounce back fuller than ever.
Have you scarified your lawn recently? I’d love to hear your thoughts and success stories in renovating old tired lawns.