Scarifying your lawn

Date Posted: 20 November 2018 

Scarifying is the process of removing the build-up of thatch and excessive root zone in your lawn. It helps return a thick, spongy lawn back into a green, tight knit surface and is something you'll need to do at least every 2 years.

(The following information applies to Couch and Kikuyu lawns only).

Over time, you may notice your lawn getting  thicker and spongier. You may also notice your lawn discolouring each time you mow it. These are indications that it may be time to remove your lawns thatch layer and thin out the root zone.  Thatch is the spongy surface material that builds up in lawns such as couch and kikuyu. The best way to describe thatch is a straw coloured exposed root type material that exists between the soil level and the blades of your lawn as illustrated in the image below.  

The more thatch you have in your lawn, the harder it is to keep green.  This is because thatchy lawns are easy to scalp with your lawn mower. The lawn blades typically only occupy the top 20mm of your lawn. For example, if your lawn is 100mm tall, you would have 80mm of thatch and 20mm of blades. If your lawn is 150mm tall, you would have 130mm of thatch and 20mm of blades.  If your lawn gets too thatchy, when you mow it you are more likely to mow off the lawn blades exposing the brown thatch underneath.  When this happens, most people raise their mower height by a notch or two so that they don’t scalp it next time. The problem is that within a few months, the lawn will grow more thatch and you’ll be back to scalping it again. The answer is to remove the thatch and then change your mowing habits. If you find that you’re scalping your lawn between mows, it’s better to mow more often than it is to raise your mower height.   Raising your mower height only leads to more thatch.

How do you scarify?

Scarifying can be done from about October through to February for Kikuyu and Couch but the very best time of year to do it is October and November.Scaryfying is a multi staged process. It involves removing the thatch, then thinning out the rootzone. Sometimes, just removing the thatch is enough. Other times, you must thin out the rootzone as well.

Step 1: Remove the thatch

Removing the thatch is a process where you mow off the surface layer off of your lawn. If your lawn is thick and spongy, it is unlikely that you will be able to remove all the thatch with one pass of your lawn mower. The best approach is to just keep mowing it down notch by notch till you have completely mown the lawn down to soil level. The more soil you can see when you’ve finished, the better job you’ve done. Rest assured, you can’t damage a couch or kikuyu lawn with a lawn mower! This process will completely remove the colour from your lawn – this is expected and normal.  Don't be surprised when you remove an enormous amount of thatch. so it's a good idea to prepare where you're going to put all the clippings. Often, just scaping is enough to rejuviate your lawn. It will return your lawn to a low, flat surface making it easier to keep green. If you want to go the whole hog, proceed to step 2!

Step 2: Scarify the rootzone

This is where you use a specialised scarifying machine to thin out the root zone. Over time, the rootzone of couch and kikuyu lawns thickens up which can impede the life and health of the lawn. Sometimes called Verti mowing, this pruning and thinning out process removes dead and woody organic matter which re-invigorates the lawn and allows it to grow new, fresh stolons and rhizomes. Scarifyers have a series of verticle blade disks that cut down into the rootzone of your lawn. They can be hired from most hire shops.

Step 3: Apply a wetting agent and then  fertilise

After scarifying and or scapling, treat your lawn with some liquid wetting agent and a complete fertiliser such as Paul Munns Greenkeeper. Liquid wetting agent will ensure that water and nutrient penetrate evenly and deeply. This will help your lawn recover faster.

As I mentioned earlier, at this point your lawn will look pretty terrible. Don't be alarmed at all by this - the warmer it is, the faster the lawn will grow back. After 2 weeks you’ll be able to see a green layer returning and typically after 4 weeks, your lawn will have completely recovered but with no thatch!    

Comments (12)

Thatch in agridark turf

By: on 9 March 2019
Hi I have agridark lawns at my house. They have become full of thatch. Should I scalp it to remove the thatch? Will it recover ok?

Paul Munns Instant Lawn Response
Hi Barry Argidark is a relatively new variety of couch and one that I haven't had any experience with. Being a couch, it can be scalped to remove the thatch and it will recover however I am unsure how long it will take. I suggest that you approach Qualturf for more specific advice.

De thatching

By: on 9 March 2019
I have a Kikuyu lawn which is 2 years old. I top dressed it with peat, which really improved it, however it will need dethatching, is it too late to do it this year?

Paul Munns Instant Lawn Response
Hi Sue, Depending on where you live, it most likely isn't too late to scalp and scarify Kikuyu. Providing your lawn is healthy and thriving, you'll need about 6 weeks of temperatures exceeding 23 degrees C to get a recovery.

Adelaide Hills Thatch Removal

By: on 28 February 2019
Hi, I have Male Sterile Kikuyu lawn located in the Adelaide Hills which has been down for about 8 years. It has never been dethatched or scarified and quite spongy. Is October - February the correct period for the Adelaide Hills? Thanks

Paul Munns Instant Lawn Response
Hi Robert, You need average ambient temperatures to exceed 23 degrees for kikuyu to grow. This would make October to February a good window to de-thatch and scarify kikuyu.

Dethatching using a mower

By: on 19 February 2019
Hi I would like to dethatch my Santa Ana couch (preferably now) .. I see that I should keep lowering the mowing height until I’m down to soil level? Can i do this repeatedly on the same day or must I wait between mows? Thanks.

Paul Munns Instant Lawn Response
Hi Matt Great question. Now is a good time to do it and you can do it all on the same day.

Lawns dead

By: on 27 December 2018
Hi I was considering subdividing my block and I allowed the lawn to die unfortunately.. It is Santa Ana couch.. I have now re considered and would like to resurrect the lawn.. I have watered it heavily without result.. Is there a possibility it will rejuvenate?? If so what do I need to do??

Paul Munns Instant Lawn Response
Hi Lidio, Santa ana is a very drought tolerant variety and will often recover if watered intensively. It tends to go into drought induced dormancy rather than dying so your chances are fairly good. I'd keep persisting. Often soil becomes non-wetting when it dries out so the application of a wetting agent would definately help

Compacted lawn escaped scalping

By: on 26 November 2018
Thanks for this reminder -- I was well on the way to a spongey summer lawn but didn't know it was a good time to scalp it now. I did the job over the weekend but there are a few high traffic areas where the grass is so compacted that it escaped even multiple passes on the lowest mower setting. These patches are still green. Obviously thatch is not a problem that afflicts these areas but I wondered if you have any tips -- i.e. is there something I should do to stimulate growth here? I have fertilised and will apply a wetting agent. I do have one of those manual lawn aerators, would that help? Or perhaps some manual scarifying with a shovel or blade (the scarifying/dethatching machines that are for hire look so big I'm not sure it's feasible).

What to do for Buffalo lawn

By: on 24 November 2018
Hi, I have a Sir Walter Scott lawn but is very spongy underfoot, what do I do.. In the past did not mind a bit of movement as it felt safer for the kids when they were playing and taking tuimbles!.

Paul Munns Instant Lawn Response
Hey Sandra, When buffalo gets spongy, it can be hard to remove the thatch. I suggest you lower your lawn mower by a notch or 2 and then mow your lawn. This will remove some colour from it. Once you have done this, you must allow it to fully recover. Keep repeating this process till the thatch thickness is 40mm thick. Remember not to scalp your buffalo too hard otherwise you may damage it.

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