When to Scarify the Lawn - Lawn Care an Expert Guide

Treat your lawn properly and you’ll have a glorious outdoor living space for most, if not all, of the year.  Get it wrong, however and the best you can hope for is to have to clean up a serious mess.  At worst you’ll do your lawn actual damage which you’ll then need to repair.

The Basics of Lawn Care

Although it may seem like an odd comparison, the basic idea behind taking care of your lawn if essentially the same as the basic idea behind taking care of your own hair.  You want the roots to be strong so that there is sturdy, vigorous growth.  When the grass emerges from the soil, you groom it partly for the sake of creating an attractive appearance and partly for its health.

Mowing and edging are both tasks which are carried out mainly for the sake of appearances.  Scarifying (raking) the lawn is mainly done for the health of the grass and the soil underneath and this will then feed through into an improved appearance.

The basic idea behind scarifying a lawn is essentially the same as the idea behind combing your hair.  You get right down to the very base of the lawn and deal with all the undergrowth which has literally been passed over by the main mower and/or edger.  In the short-term, this can create quite a mess, but once you’ve cleaned that up, your lawn will both look better and feel better and therefore will grow better.

The Best Time to Scarify a Lawn

If you ask the average gardener when to scarify the lawn, the chances are that they’ll say “autumn and spring” or maybe “September and April”.  If you ask a gardening expert when to scarify the lawn, they may add “when the conditions are just right”.  We’re going to say that the best time to scarify a lawn is when it gets the best results.  To understand what that means in practice, you need to understand what scarifying does and why it matters.

The Basics of Scarifying

Scarifying is basically going to remove all the unwanted dross from your lawn and once this is cleared away you’re going to see what your lawn really looks like.  You then have the opportunity to fix any issues and leave your lawn to repair itself.

That’s the theory.  In order for the theory to work in practice, you need to scarify the lawn at a time when the grass is already growing strongly and when the environmental conditions are perfect for supporting further growth.  This means you want an extended period of warmth (but not excessive heat) and sunshine with light to moderate rain (or the ability to water your lawn effectively). 

Add in the fact that scarifying is a pretty intensive treatment for your lawn, meaning that you only want to do it a couple of times a year, and you can see why autumn and spring are the standard times to do it.  The key point to note, however, is that you don’t just want to scarify your lawn any time it takes your fancy in spring, or even in April and September, you only do it when the conditions are exactly right.  If there’s a year when you don’t get those conditions, then it’s usually much better just to let your lawn be and wait for another year.

A Quick Note on Lawn Scarifying Services

Lawn scarifying is often at least fairly hard work, so it can be tempting to pass it off to a lawn scarifying service.  While this is fine in theory, the fact is that you need to fit your lawn scarifying around growing conditions, not around the times you need or want work.  Scarifying a lawn in the wrong conditions can actually cause a lot of damage. 

So, while we’d never say never, we would say that usually there’s only a few weeks each year when you can scarify the lawn without causing damage.  If you can get a lawn scarifying service to do the work for you at the right time, then it could be money well spent.  If you can’t be sure of getting the work done when it needs to be done, however, then we’d strongly recommend that you leave well alone.

As a final point, if any lawn scarifying service offers to scarify your lawn in winter or summer, then, barring very unusual circumstances, you probably want to make a note never to use them as it looks suspiciously like they’re simply trying to take care of themselves rather than to take care of your lawn.

By contrast, what you could do is hire a scarifying machine, which can make the job much easier.  You can also buy them, but you might find them a bit pricey for a job you’re only going to do a couple of times a year (unless you have a really large lawn).  If you are in the market for a scarifying machine then Black+Decker do a good one at a reasonable price.

How to Scarify a Lawn Properly

Here is a detailed guide as to how to scarify a lawn.  For the most part, the procedure is exactly the same in both autumn and spring, but where there are differences we have noted them.

Plan ahead

We cannot overemphasize how important it is that your grass is already growing strongly.  The lack of grass growth is the number one reason why you don’t scarify a lawn in winter or summer even if you get a short spell of excellent weather.

Deal with any weeds and moss well in advance

If you need or want to use a weed killer or moss killer, then ideally you want to do this a month before you scarify the lawn.  This may seem like a long time but you not only want to give your grass a chance to recover (did we mention the importance of strong growth?) you want to ensure that you can overseed any bare patches without the seeds being poisoned by the weed killer or moss killer. 

As a minimum, wait at least two weeks after using weed killer and/or moss killer, otherwise you may spread any remaining spores which have survived the treatment but aren’t quite strong enough to grow.

Ideally, you want to use a weed killer and/or moss killer which also feeds your lawn as this will encourage it to grow more strongly (we think we may have mentioned that this is really important).

For the sake of clarity, do not confuse raking away weeds and moss with proper lawn scarification.  When you clear away dead weeds and moss, all you’re doing is removing surface debris.  When you scarify your lawn, you’re getting right down to the soil and clearing away anything which shouldn’t be there.

Start lowering the height of your lawn a week or two in advance

There are three reasons for lowering the height of your lawn.  Firstly, it reduces the resistance to the scarifying process (think about combing long hair versus combing short hair).  Secondly, it gets more air into the soil, thus improving the air flow and allowing it to dry more quickly.  Thirdly, healthy grass, like healthy hair, is at its strongest near the roots and you want your grass to be as strong as possible before you start scarifying your lawn.

The day before you plan to scarify your lawn, mow your lawn as short as you possibly can.  If something then happens that you can’t scarify your lawn as planned, just keep your grass short until the opportunity arises.

For the record, if you’re in the habit of leaving your grass clippings on your lawn to fertilize it, then this is one time to make an exception to the rule and rake them up.  You can always use them for compost (remember to mix or turn them into the pile rather than just dumping them on top).

As before, raking up your grass clippings does not count as scarifying because you’re just clearing up surface debris.

When you think you’re ready to scarify your lawn, check for moisture before you start

What you want is dry grass but soil, which is dry to the touch but springy enough to show that there is moisture underneath.  It’s OK if the soil is slightly moist to the touch, but the grass must be dry.  Often the best way to get these conditions, is to scarify at a time when there is moisture early on the day, but to wait until the afternoon.  This will give the sun a chance to dry out the grass while the soil underneath it stays damp.

Go in with a rake

If you’re looking for a rake for scarifying a lawn, we’d suggest a couple of options from Wolf Garten, this one for autumn and this one for spring.  Remember you have to buy the pole separately.  The key point is that you need a scarifying rake with metal tines.  Plastic tines are fine for raking away leaves, but we’ve yet to find a rake with plastic tines which would stand up to scarifying a lawn.

The basic approach to scarifying a lawn is the same in both autumn and spring, but in autumn you typically go in with a much heavier hand, partly because you’re settling the lawn for winter and partly because there’s much less danger of any resulting bare patches being invaded by weeds. 

Shaded areas are an exception to this rule as the lack of sunlight means that they may get very bare in autumn.  This goes double for areas under trees, at least ones which shed their leaves in autumn as these can literally suffocate the grass underneath them with the result that new growth is basically impossible.  These areas are best treated lightly in autumn and thoroughly in spring.

Scarifying technique

Unless you have a really tiny lawn, you’re going to want to approach it one part at a time.  If you have handy garden landmarks, then you can use them to define working areas.  If you don’t then it’s a good idea to bring some markers with you.  These can be anything you like, just as long as they stay in place when they’re down and can be moved relatively easily.

You want to work with one foot slightly in front of the other.  This keeps you both comfortable and balanced while giving you freedom of movement.  You will need both hands on the rake, one up by the top of the handle and the other as far down as you can stretch comfortably.  It’s a really good idea to wear light gloves for scarifying a lawn as they will both protect your hands from the friction of the raking movement and give you better grip.

Start raking with light strokes and then go in deeper and deeper until you stop pulling up thatch.  Clean your scarifying rake as necessary as this makes the process both easier for you and more effective on your lawn.  Once you stop pulling up thatch, turn your rake 45 degrees in autumn and 90 degrees in spring and repeat.  This will bring up more debris, again, work until it’s clear and then move on to the next patch of lawn.

Lawn Aftercare

As we’ve mentioned already, scarification is a pretty intense treatment for your lawn, so you want to give it some tender, loving care afterwards.

Make sure your lawn gets enough water, if you don’t get rain then go out and water it manually.  Reseed any bare patches and give your lawn a good feed, but don’t overdo the fertilizer as this can both damage your lawn and encourage the build-up of thatch.

If you follow the steps we’ve outlined above, your lawn may look pretty bad for a couple of weeks, but then it will start to recover and it will soon look far better than it did before.