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Articles within the Scarifying & Raking Category

Knowing why a lawn needs scarifying or raking and how to go about it will help you manage the lawn with less effort and with perfect results

What is Raking & Scarifying

Scarifying is mainly influenced by grass type; this is going to dictate whether or not your lawn is going to need scarifying or de-thatching. If you’ve got anything other than a mainly rye grass lawn then it will need doing at some time. And if it’s an ornamental or so-called ‘luxury lawn’ full of the fine fescue grasses then you’d better start to love scarifying.

Raking is influenced by the amount of moss that grows in your lawn. If it’s wet, shady or perhaps on a clay soil then you’ll have your share of moss and you’ll need to do some raking.

So, like it or not you had best be prepared. DON’T bury your head in the sand and hope the problem will go away. It won’t, and year on year it will get worse to the point that you have little or no grass left! The BEST and EASIEST way to tackle problems of thatch or moss is to tackle them early. Let the problem reach CRITICAL and you may not have a lawn to save!

Scarifying or de-thatching

Lawn Scarifying

Metal blades Scarifying into the Soil

Lawn scarifiers use steel blades to cut out thatch; hence it is also known as de-thatching. In machines these will rotate whilst manual tools like the rolling lawn scarifier will not.

Lawn thatch by its very nature is removed more easily by this cutting action and the result is a firmer lawn that allows the passage of air, nutrients and water easily into it. Take scarifying a step further by letting the scarifier blades cut into the soil and you will open the soil surface and make an ideal seed bed for introducing new grass seed to your lawn.

The blades also ‘prune’ the grass plants because it cuts them downwards rather than cross cutting as in mowing. This pruning, just like pruning a bush or plant causes extra shoots to grow thus thickening the turf.

The ‘chopping’ action is also a good way of controlling some of the coarser or delicate weed grasses such as Yorkshire Fog and Annual Meadow Grass. It can also help control creeping weeds such as speedwell and trefoils (yellow suckling clover).

Raking or de-mossing the lawn

Lawn Raking

Wire Tines above the Soil Level

Whereas scarifiers use blade tines, rakes use wire tines just like on a fan or spring-bok lawn rake.

Wires are best for raking because moss is not rooted and comes away quite easily. This means pulling or ripping the moss out rather than cutting it out is best. Wires are also best for giving the lawn a light raking after a drought to clear dead brown grass that has accumulated.

The wires on some machines are often on a flail system; in other words they are not fixed or rigid but swivel around a central axle. This means if they hit anything hard they just flick out of the way. Consequently flail wires are excellent for moss removal without too much lawn damage. Smaller raking machines have quite thin wires that are quite flexible thereby reducing damage.

If you intend to rake the lawn by hand this can be quite exhausting because  the rake needs a lot of pressure to work which in turn increases resistance and friction. You will find the rolling lawn scarifier is ten times easier to use being excellent for both moss and thatch.

View the Rolling Scarifier

What is Lawn Thatch?

Lawn ThatchLawn Thatch Layer

Grasses propagate by seed with some also producing side shoots or runners. These side shoots help the grass spread and are either just above the soil surface (stolons) or just below it (rhizomes). This ‘spreading’ helps the turf knit and become thick and dense. Ideal if you want a little ball to roll smoothly across it!

However, nothing is forever, and at some point the parent grass plant and some stolons and rhizomes die to be replaced by younger stronger plants. The problem is that the growing part of the grass plant (crown) together with the stolons and rhizomes contain a chemical compound called lignin which makes them very slow to rot or decay. And because they don’t rot they start to build up, layer upon layer until there is too much. This is thatch!

Not all grasses and lawns produce thatch. Rye grass, though not the finest of grasses is notable for its dark green colour, hard wearing nature and the fact that it doesn’t produce any thatch. Therefore, your typical ‘luxury’ type front lawn with no rye grass will be thicker due to the ‘spreading’ nature of the grasses AND need scarifying, whereas your ‘utility’ type back lawn with high rye grass content won’t. This is one of the reasons rye lawns are so much easier to look after particularly if you’re a reluctant gardener!

The Right Amount of Thatch

Too much thatch is considered to be over half an inch. It makes the lawn feel ‘spongy’ underfoot. As well as feeling like a sponge it can also act like a sponge withholding valuable water, air and nutrients needed by the roots of your lawn.

Conversely a little thatch, perhaps quarter of an inch is beneficial. It is not sufficient to hold valuable nutrients away from the soil and grass roots, but is enough to cushion and protect the valuable crowns of the grass plant and insulate the soil from the drying effects of wind and sun.

Left to its own devices thatch will build to the point where the grass starts rooting into it. This is now a critical situation. The grass grows roots into the thatch because rain and fertiliser is held by it. The soil becomes dry so the only way for your lawn to survive is for the roots to go where the water is – into the thatch.

You now have two problems. Firstly, the thatch will quickly dry in the summer so your lawn will go brown early and quickly. Secondly, as your lawn isn’t rooted into the soil it is a bit like a loose carpet. One good tug with the lawn mower or scarifier and chunks come away!

Checking for Thatch

Before you start scarifying and de-thatching your lawn make sure the problem IS thatch!

In addition, raking or scarifying your lawn without good reason or at the wrong time can harm your lawn. I’ve met enough lawn owners to know that some have a mind-set that on the dot of March 1st out comes the scarifier, regardless of whether or not thatch exists! Therefore, check first and scarify only if needed.

Brown grass

Just because you see some brown grass in your lawn doesn’t automatically mean it’s thatch. It could be the result of a dry summer when a light raking will clear out the dead brown grass. It could also be the effects of disease, particularly red thread which kills just the leaves of the grass (not the plant) leaving behind a lot of patchy dead brown grass. Raking or scarifying when disease is about can possibly spread the disease and weaken the grass, turning a mild infestation into a disaster!

Spongy lawn

Your lawn may also feel spongy but this does not necessarily mean thatch. Give a small area of your lawn a light rake; then get down on your hands and knees and have a close look. You may find lots of moss that wasn’t previously visible has been exposed. You can now make plans to use your lawn raker in spring or autumn as part of a moss control programme.

You may also find that a test raking will lift up the grass and once ‘stood up’ you’ll find it’s an awful lot longer than you first thought!

This ‘stood up’ long grass has been previously packed down by the repeated rolling by a mower with a roller. The roller lays the grass down forming the ‘lawn stripe’ but over time it can pack the grass excessively forming a spongy bed. The best way to resolve this is to lightly rake the lawn then mow it immediately afterwards. You may need to do this several times which will cause your lawn to become quite brown as you’ll have removed most of the grass leaves and be left with yellowy brown stems. It will soon recover but like all invasive lawn treatments only do this in good growing conditions. Prevent this happening in the future by changing mowing direction at least every few cuts.

Take samplesGrass Thatch Sample

Finally you need to take a small sample of lawn and have a look at it. Use a bulb planter or your garden spade or trowel to take a few samples from various places around your lawn. You don’t need a big piece, anything from half an inch across but at least 2” deep. The layer between the grass and the soil is the thatch layer. It is compressible and fibrous. Anything over a quarter inch means you need to scarify your lawn.

If the thatch problem is so bad that the grass has rooted into it then you will lose most of your lawn if you use the scarifier. If you want an easier option but not as quick then you should hollow tine the lawn spring and autumn for a few years AND smash the cores over the lawn. The hollow tines or corers will cut out some thatch, the resulting hole will allow water and nutrients back into the soil; the grass will start rooting into the soil again and the redistributed soil from the cores will increase the rate of thatch decay. It does work as long as you don’t have deep compaction. If this is the case it is the compaction that is causing the thatch and you’ll never get rid of it whilst the compaction remains. Time to renovate and start afresh I’m afraid!

View the Hollow Tine Fork

When to Rake or Scarify

Rake and Scarify the LawnRaking or scarifying your lawn, whether it be for thatch or moss, is in the long term an extremely beneficial procedure but in the short term it can make a right old mess of it. Though it will recover and be better than ever, getting there in the shortest possible time is our ultimate objective.

So many times I see people doing a thoroughly good job with their scarifying but at the wrong time of year or in the wrong conditions. This means the lawn is an eye sore for weeks if not months afterwards. You may also cause damage to your otherwise healthy grass plants thereby worsening the problem. Makes me shudder!

Time your programme according to the ability of the lawn to recover. This means warmth, sun and rain whilst avoiding cold, heat or drought. In other words you need good growing conditions and if your lawn isn’t growing well before scarifying then it won’t grow well afterwards leaving you with a much disfigured lawn!

Spring: Raking & Light Scarifying

Light de-thatching or scarifying and moss removal can be done in spring and or autumn. Spring generally means sometime in April just as things warm up thereby increasing the growth and recovery rate but before the heat and dryness of summer slows things down. Autumn would generally be late August or September as the rains start but before the cold sets in.

Autumn: Heavy Scarifying

For heavy thatch or moss infestations requiring deeper scarifying or raking then try to stick to the autumn period. Why?

Heavy raking or scarifying is going to seriously thin the lawn leaving soil exposed in many places. This makes an ideal seed bed not only for over seeding with new and improved grass seed but also for all the weed and weed grass seeds floating around. By confining this intensive treatment to August or September you will avoid the bulk of the years weed seeds. If you do this in spring you’ll just replace your moss or thatch problem with a weed problem! Having said that, there are a few exceptions when spring is the best time:

  • It is better to rake or scarify in spring if you were unable to do it the previous autumn perhaps due to bad weather rather than put it off. Keep putting it off from autumn to autumn could mean you’ll have a bigger problem than a few weeds!
  • If the area to be scarified is shady. Shady areas will thin over winter and thicken up from spring onwards. Therefore if you scarify in autumn you’ll just make things worse.
  • If the area is under trees. The shade from trees plus the autumn fall of leaves will reduce grass health and vigour but in spring – late March through April - the trees are bare allowing maximum light to your lawn enabling good growth and maximum opportunity for new grass seed to get growing.

Ready the Lawn for Scarifying or Raking

Planning ahead is important. You need short dry grass for raking or scarifying so bring the grass height down gradually over a week or two before hand. This doesn’t shock the grass whilst also allowing air deeper into the turf helping dry the grass.

If you have any weeds in your lawn then you had best get them a week before you scarify. Though scarifying can help control some creeping weeds, nothing is more permanent than a little correctly timed and placed weed killer.

The final bit of preparation is to have good soil moisture so that the lawn recovers as quickly as possible afterwards. If there is too much (soft ground) or too little (dry hard soil) you need to either wait until the conditions improve, assist them to improve or not rake or scarify at all.

The day before attacking the lawn mow it as close as possible without scalping. Long grass just creates resistance to the scarifier with ultimately more rubbish to collect. Dry grass and moss makes life a lot easier as well. Plan to rake on a dry day with no dew around. The afternoons are often best. If the weather doesn’t play ball, keep the grass short until you get another raking opportunity.

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How to Rake & Scarify

The best advice is ‘tease it out’

Manual Scarifying or Raking

Rolling Lawn Scarifier
If you’re using a hand held rake wear leather gloves with talc in them to prevent blistering. Only moderate pressure is required and rake repeatedly to lift out the moss or thatch. The easier option, and therefore the better option in my mind is to invest in a proper lawn scarifier that has wheels. It’s far less work, enables a gentle teasing action and just as effective.

You will find it easier and get better results by doing the lawn once in one direction and repeating the raking at a slightly different angle – don’t go at right angles as this causes too much damage. Use the mower or a landscapers rake to collect the debris.

Using Powered Scarifiers or Lawn Rakers

If you’re using an electric raker then repeated runs up and down the lawn to ‘tease’ the moss or thatch out will be best for the machine and grass.

If you’re using a petrol scarifier you have the power to go deep but don’t! Teasing the moss or thatch out with progressively deeper runs is the best way.

If your machine has height adjustment (most do) then set it up (turned off please) on a hard surface so that the blades or wires just touch the ground. Then do a few metres on the lawn and make minor adjustments so that debris is removed without great chunks coming up – tease it out!

Moss and thatch collection is often best with a large 2 to 3 foot wide ‘landscaper’s or hay rake’ or by using the lawn mower. The mower does an extra cut helping the debris to pack better. The box is also normally bigger than those on rakers or scarifiers so I suggest leaving the box off the scarifier.

If the moss or thatch is particularly bad you may need to collect it regularly to keep the lawn clear for the next run with your scarifier.

Changing direction for the second and progressive runs is beneficial. You’ll remove more each time and complete the job sooner.

As progress is made and less debris remains you can lower the machine for each new run. If you are scarifying with blades you can even allow the machine to penetrate the soil by up to ¼”. This also helps seed to take if you are going to wisely over seed the lawn on completion. If you are using an electric lawn raker or wire tines in your scarifier or mower then keep them off the soil as they cause too much damage and can also break.

At some point you have to decide how far to go with debris removal. If the moss or thatch is not particularly bad or you’re doing this in spring then two runs, one up and down and one across should suffice. Keeping the machine on the high side will minimise damage and enable the lawn to recover in no time with a little rain and fertiliser. However, if the problem is bad and the conditions are good, then a total of four or five progressively deeper runs is in order. The resulting landscape (not too dissimilar from the dark side of the moon) may well scare you, in fact, it should scare you but, with a little help it will come back better than ever!

Scarifying and Raking Tips

If there are bumps in the lawn you may cause damage in these areas even though you are only raking or scarifying lightly. Unless you take action to correct the bumps this damage will be inevitable and perhaps typical of most lawns. Don’t worry, just follow the recovery procedures and in a few weeks the lawn will be as good as new.

If shallow dips or bumps are a problem and you feel that top dressing will resolve much of it then top dressing (3-4 kilo per square metre) after scarifying is ideal. If you’re also overseeding this is even better. Depending upon which book you read some say seed then top dress and others top dress then seed. I’m in the latter school.

Sometimes thatch is so bad that, as explained earlier the lawn has rooted into it. In this case either great lumps of lawn will literally pull away or you end up with just thatch and no grass. In this case you need to consider whether neglect is the cause or if soil compaction and disease is the cause. If it is the latter consider a new lawn, if it is the former just keep going with the scarifier until you get down to the soil. The likelihood will be that, in a heavy thatch situation, you will remove most living grass; therefore you will have to re-seed the lawn. The moral of the story; A stitch in time….! See Over Sowing with New Grass

If you’re feeling really adventurous this is also a good time to hollow tine or spike the lawn. Just follow the instructions in Lawn Aeration & Equipment

NB If you are de-mossing you don’t necessarily need to kill the moss first. For more info go to Moss Control

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