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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


Verticutting IS vertical mowing and the objectives are:

  • Depth Comparison

    To prune the grasses to improve tillering and stolon formation. This increases turf density and is very important for all fine competition turf such as bowling and golf greens. Not so critical for an ornamental lawn but loads of fun all the same!

  • To control thatch. The blades of a verticutting reel are much finer and more numerous than those on a scarifying reel. They are designed to be used above the thatch layer to remove dead and dying grass plants that will ultimately contribute to the thatch layer.
  • To produce an upright grass prior to mowing to give a cleaner more consistent cut.
  • As a cultural method for controlling weeds and weed grasses

Used regularly, every week to two weeks in good growing conditions from April to September will help maintain a firm low thatch surface right through the season. This will make for a faster playing surface and make scarifying in the autumn that much easier and cause far less damage.

WARNING: This is perhaps the easiest way the ruin your lawn. Do NOT allow the blades to contact the soil. If your lawn is bumpy these will need to be resolved before verticutting.

Good quality professional scarifiers have interchangeable reels enabling brushing, verticutting, raking and scarifying with the one machine.

Verticutting Blades

Scarifying Blades

Images courtesy of SISIS

Types of Scarifier & Raker


Quite often marketed as power scarifiers, garden scarifiers, electric scarifiers or electric lawn rakers. ElectricThough called scarifiers many have just wire tines and are lawn raking machines at best. They are good value and if you have a mossy lawn between 100 and about 250 m2 then these are a great investment.

Some manufacturers have machines with inter-changeable cassettes; wires for moss and blades for scarifying.  They make for good moss rakers and reasonable though light weight scarifiers; ideal for small to medium lawns.


If your lawn is much over 300m2 and needs scarifying then the only way of making the work less arduous is to use a petrol scarifier. If you’re caring for a fine or ornamental lawn only a good quality sharp petrol scarifier will be able to cut through the thatch cleanly without excessive damage.

Petrol powered scarifiers start at £300 and go up to several thousand pounds for professional pedestrian machines. Chances are that if your need is not twice a year then hiring a machine for a day or so will be your best bet. Most hire companies have them but do check for:

  • Blades – they need to have a reasonably sharp point and should not be too rounded
  • To reduce damage to a bumpy lawn try and get a scarifier with swinging or flail type blades
  • If moss is your problem make sure wire tines can be fitted into the machine. If not flail or swinging blades will do
  • For top quality lawns, sharp fixed blades are the only way to go!

If you decide to buy then the above will help you decide what to look for. Interchangeable cassettes being the number one priority if you have both a moss and thatch problem. Of course if you have an electric lawn raker or can put a raking cassette into the mower then all you need is a machine with scarifying blades.

There are many many manufacturers and many different prices so just get the best you can afford. Quite often a pre-owned machine makes sense and if you can grab one, perhaps a SISIS from a bowling club then do so. You’ll have a superb machine with all the variations you’ll need.

Lawnmower CassettesQualcast-cassette-120

Atco, Qualcast and some other cylinder mower manufacturers produce scarifying cassettes for their cylinder mowers. These are excellent for light raking or de-mossing the lawn and are a good way of getting additional use from your mower. They are no substitute for a scarifier if de-thatching the lawn is your goal but it does mean a simpler and perhaps cheaper choice if a scarifier is also required.

Hand Held or Manual

The simple spring-bok or spring tine rake is perfectly adequate for moss removal and raking small lawns. However, if you want to make hand scarifying and raking a lot easier then a rolling lawn scarifier is perfect.

Images from the top:
Alko electric raker and scarifier
Dori petrol scarifier
Qualcast mower raking cassette
SISIS Auto Rotorake
Manual rolling scarifier

How much Seed do I need?

Quite often the seeding rate on your grass seed bag is given as a range. This is particularly true for over-seeding rates on lawns. Here is a short guide on how to decide when to use high or low grass seeding rates assuming your seed has a high purity rating and pedigree.

Patching or Minor Repairs

It’s going to be difficult to calculate seeding rates for a few square inches or metres of lawn. Most home owners put in far too much seed which causes strange dense tufts later in the year. Therefore put seed in at between 10 and 20 seeds per square inch. That will be plenty, I promise.

Mowing Height

If you are determined to mow your lawn as close as is tolerable for that type of grass then increase seeding rates by 20 to 30% above the highest rate

Clean Seed Bed

If when establishing a new lawn you have spent a lot of time and patience preparing a weed free soil you can lower seeding rates to perhaps half the recommended amount. It will take slightly longer to establish and thicken however. If you haven’t done anything to kill or remove weeds other than dig them in then add 20% to the higher seeding rate.

Time & Timing

If you need your lawn to establish or recover and be useable as quickly as possible increase seeding rates by 20 to 50% above the highest rate.

If you are seeding in less than ideal conditions (cold or dry) increase seeding rates by up to 100% to compensate for losses. However, most seed won’t germinate below about 80C (except Lawnsmith Coolgreen) or if  conditions are too dry.

Over-Seeding after Raking or  Scarifying

It is always a good idea to over seed after scarifying as this helps the return to a dense turf as quickly as possible. It is also a good opportunity to introduce new types of grasses for an improved lawn.

Depending on how heavy you’ve been with the scarifier determines how much seed to add. A light scarifying may only require a half rate of seed, a typical autumn scarify may require seed at the new lawn rate whilst a heavy scarify which has been into the soil should be over seeded by up to 50% more than the new lawn rate.

Seed Age

Increase the seeding rate by perhaps 10% for every year the grass seed has been kept. Some seed kept in cool, very dry and dark conditions lasts for many many years. However, if you have an important job to do best use fresh seed or test your seed before use.

To test old seed:

Take an old clean cloth and fold it into a flat pad about an inch thick. Place this in a tub or bowl with half an inch of water. The cloth will soak up water and become saturated. The top of the cloth pad is now an ideal place to sprinkle perhaps 20 to 25 seeds.

  • Place the tub in a warm place away from drafts – airing cupboards and utility rooms are usually ideal
  • Maintain a water level of about half an inch until germination
  • Germination will take between 5 and 14 days depending on seed type and temperature
  • When sprouting gets to ½” count how many seeds did and how many didn’t germinate
  • If only half germinated double your seeding rate
  • If less than half germinated throw it away and buy fresh!

How to Over Sow with Grass Seed

Over seeding an existing lawn requires a little more attention than seeding a new lawn.

How Much Grass Seed?

When you’ve decided which lawn seed to use, the instructions should tell you the rate at which it needs to be applied. Quite often the over seeding rate is lower than the rate for starting a new lawn though sometimes adding more, particularly if rye grass is included, will speed recovery. However, if you are trying to improve your lawn by changing the type of seed then adding more will cause more of a change.

Do NOT automatically assume more is better! I’ve seen patch repairs done where you can’t see the soil for grass seed. This will cause extremely dense growth that will stick out like a sore thumb. If in doubt stick to about 10 to 20 seeds per square inch.

The next blog page will cover all the variables for seeding rates.

Over-seeding Procedure

  • If the lawn is rather dry and rain is unlikely, start building a reserve of water in the soil by running the sprinkler for an hour or two a day for several days depending on how dry it has been. You don’t need soggy ground but seeds and seedlings need ‘some’ water to germinate and root. This should be done after renovating (raking, scarifying or aerating) but before seeding and fertilising
  • Make sure you have fertilised the lawn before adding the seed
  • Split the seed into two lots if you are confident of spreading evenly, otherwise split into four equal lots
  • Spread the seed by hand or spreader working in a different direction for each lot e.g. north to south, then south to north and east to west etc. This will ensure even coverage. A smaller than recommended setting (say 1/3 to 1/2 open) on the spreader will prevent you running out of seed too quickly but means more trips up and down the lawn.
  • If there is quite a lot of grass sticking out of the lawn after scarifying then the seed you are adding will stick on it preventing contact with the soil – not good. If you can, drag a garden hose, a piece of wire mesh fencing or a large brush over the lawn to knock the seed off the grass and into the soil
  • Next roll the lawn. If you haven’t got a roller but you have a lawn mower with a roller this will do just fine. Might be best with the engine off though! If you don’t have either and the lawn is not too big, start treading up and down the lawn. Good seed soil contact will improve the result no end
  • Finally, if at all possible give it a light watering every day for a couple of weeks if there is no rain. Enough to keep the seed from drying without washing it away. If watering is impossible then try and schedule your seeding for a wet period
  • Unlike starting a new lawn you should mow your lawn as normal. However, to reduce stress on the new grasses mow at least weekly for the first 2 months, no lower than 1” and preferably at 1.5″ to 2″, with sharp blades on dry grass

NOTE: Because of the elongated shape of grass seed it does not ‘flow’ consistently through rotary or broadcast spreaders. This means that though a spreader is an excellent method for spreading seed settings are unreliable which is why we suggest a one third open setting to start and applying in several lots to ensure consistent even coverage.

Patching Procedure

If all you need to do is seed a few badly damaged patches then follow the procedure above but lightly sprinkle (10 to 20 per square inch) seeds into the patches. Watering before and after and fertilising remains the same.

Reasons to Over Seed

This is a simple process and one that is often neglected. Perhaps it appears to be too much trouble or it’s the cost of grass seed that stops people doing it! Seed isn’t cheap but it is unlikely to cost more than an evening at the pub!

The consequences of not over seeding the lawn are quite possibly delayed recovery, an unsightly lawn for quite some time and a guaranteed weed invasion. By adding seed you will be bringing your lawn back to its former glory sooner, and, if you’re adding new varieties of grass seed you’ll be improving the appearance and life of your lawn. So, I highly recommend you take the easier and cheaper option of over seeding your lawn whenever you have the opportunity.

What Lawn Seed to Use?

Firstly decide on whether you are trying to match the existing grass or to add new varieties and therefore change the look of the lawn. A word of caution though; if you just need to patch a few damaged areas then the same type of grass is a must. Unless you have original seed it is unlikely you’ll get a perfect match but you can generally get close.

Matching grass type

If you don’t know what type of grass you have then just get down on your hands and knees and look at the grass blades. If all the leaf blades look like bristles then the chances are you have a ‘none rye’ lawn so I’d recommend a fescue mixture such as Lawnsmith® ORNAMENTAL.

On the other hand if your lawn is predominantly grass with flat leaves then a rye mixture is in order such as Lawnsmith® EASYGREEN which has heavy rye content. If the lawn appears to be a mixture of flat and bristle grasses then Lawnsmith® CLASSIC will match very nicely.

As is often the case, distinct areas of lawn are bristle like and others are flat leaved.  This ‘patchiness’ can often be a good reason to change or improve the look of your lawn by over seeding the whole lawn with the grass seed mixture of your choice.

Changing grass type

If you’d like to change the way your lawn looks or behaves then over seeding with a different type of seed will bring about appropriate changes. For example if your rye grass play lawn is no longer played on because the kids have grown up you can add some luxury to it by over seeding with Lawnsmith® ORNAMENTAL seed. On the other hand if your lawn or areas of lawn are shady add Lawnsmith® SHADYGREEN seed; if it suffers from drying or drought then over seed with Lawnsmith® STAYGREEN seed or if you want to extend the use of the lawn into cooler weather then use Lawnsmith® COOLGREEN.

These additions will not completely change the lawn as you will still have plenty of your original grass left and you will now have a blend between the two. If you want to change the grass completely see Renovating the Lawn or Creating a New Lawn.

Just to confuse the issue even more, lawns, as they mature can become a hotchpotch of different grasses. If this is the case I wouldn’t try for a match and I’d over seed the whole lawn with your chosen grass seed to try and improve the uniformity.


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