Do your grass some good with these top autumn lawn care tips

Autumn is the ideal time to treat your lawn and help to maintain its glorious green lushness. If you leave your lawn care until spring, it may suffer over winter, becoming patchy, discoloured and covered with moss that thrives in damp weather.

Attempting your lawn care in spring is much harder and less effective as the lawn hasn’t had time to recuperate. The grass will be trying to grow again, without having had enough recovery time.

There are five key activities to undertake when doing your autumn lawn care. These are scarifying, aerating, top-dressing, overseeding and feeding.

I spoke with James Bourne, head of lawns at RHS Garden Wisley, to get his top autumn lawn care tips.

Scarifying your lawn involves removing the thatch. Thatch is a mix of dead material made up from fallen leaves, dead grass blades and other organic matter that lies on the surface of the lawn, just below the blades of grass.

It needs to be removed because it smothers the surface, preventing the grass from knitting tightly together to form a lovely, thick sward. Thatch is at its maximum depth in autumn, after a season of mowing grass.

The thatch can also prevent moisture from reaching the roots of the grass, making it susceptible to drying out in the summer. It also impedes fertilisers from reaching the grass roots when feeding your lawn.

Finally, a dense layer of thatch on your lawn prevents air movement among the blades of grass and this can lead to fungal problems, such as red thread (brown patches with red, thread-like fungal growth), fusarium (a fungal disease that can cause the grass to die) and rust (a yellowish-orange coloured powdery substance appearing on blades of grass).

When is the best time to repair your lawn – autumn or spring? We reveal all.

Prepare yourself for a vigorous workout! The most common method of scarifying a lawn is to use a spring-tined rake to scratch at the surface of the lawn. You will be amazed at how much dense thatch you can remove using this process.

However, Bourne does emphasise caution when it comes to using a spring-tined rake: “If you are going to invest in one single piece of equipment for autumn lawn renovations, I would suggest purchasing a specific scarifying rake. They are designed to just pull out the thatch.

“Often what you find with a spring tined rake is you end up ripping out just as much healthy grass, as you do the dead grass and thatch. So just be careful if using a spring- tined version.”.

Going over the lawn once with a spring-tined rake would probably be enough for most people, although lawn afficionados will probably do it two or three times.

If you do it more than once, it is best to do it at various angles to maximise the amount of thatch you can remove, rather than repeatedly going over it in the same direction.

For much larger lawns you can buy or hire machines for the job.

Collect up the thatch and add it to your compost heap. Don’t be tempted to collect up the material with a mower with a collection box on the back.

As Bourne explains: “Going over the lawn with a mower to collect up the thatch flattens the blades of grass. If you were considering scarifying a second time, directly after the first you will want the blades nice and upright not lying across the thatch you are trying to collect.”

Another autumn lawn care tip is to aerate the ground. However, Bourne says that if you only have time for one of the processes this autumn, then scarification is more important.

However, aeration will certainly still help if you want a really healthy-looking lawn. Bourne says: “I would only aerate the lawn in autumn if you have had a problem with drainage or its damp and therefore, have a lot of moss.”

Aeration will help improve drainage, alleviate compaction and increase air flow to avoid fungal diseases.

Breaking up the compacted ground in autumn, particularly if it has been used a lot during summer, will allow the root system to develop and seek out much needed moisture and nutrients.

Another tip Bourne has to help take the strain out of aerating with a fork is to just do a section of it. “Aerating an entire lawn with a fork can be hard work.

“Instead, just look for the worst patches, such as mossy areas where it has been damp, or perhaps just a simple desire line – where the ground is compacted. Just target those areas, and don’t worry about the rest of it.”

Although you can buy or hire lawn aeration machines to do the work for you (sometimes called pluggers), the simplest method for a small area is to use a garden fork.

Simply push the tines of the fork about 10cm (4in) into the lawn, wiggle it around a bit and then pull it out again. Repeat this process at regular intervals over the area you are aerating.

Bourne’s tip is to insert the tines of the fork backwards into the soil so that their natural curve faces towards your feet rather than away from you.

“It’s much easier to pull the fork in and out of the ground at that angle. It saves straining your back and shoulders. After all, aerating an entire lawn with a fork can be hard work, but this makes it much more comfortable.”

If that sounds too physical for you, there is an easier option.

You can attach purpose-made spikes to the underside of your shoes. All you have to do is slowly walk up and down your lawn a few times and the aeration is done for you.

Top dressing is adding a thin layer of organic matter to the surface of the soil. This can just be sand or compost, but most people use pre-mixed bags of ‘top dressing’ made commercially and sold through retail outlets. This mix is usually made up of loam and compost.

Adding top dressing replenishes and improves the soil structure as well as improving drainage and also partly replaces lost nutrients from the summer. It will also help grass seed bind to the surface and germinate when you come to overseed the lawn.

Bourne recommends adding a layer of top dressing after scarifying and aerating. Spread the top dressing equally over the lawn at a rate of one shovel per 2 sq m (per 21.5 sq ft) and then sweeping it into the ground using either a broom or a rubber rake.

No top dressing should remain on the surface above the leaf blades, as this can kill the grass beneath. It should all be swept under the grass blades.

If you have aerated previously, then the top dressing can also be swept into the holes as well as over the surface.

Bourne offers advice on the best time to add top dressing: “Ideally this should be done on a day when it is not wet or dewy on the ground. Otherwise, the top dressing will be sticky and won’t brush into the soil.”

To sow grass seed successfully, Bourne says you should ideally overseed the entire lawn, not just bare patches. “If you just sow sporadically in bare areas, it will unfortunately leave you with an effect a bit like a patchwork quilt. The newly sowed patches will really stand out. You need to get a more uniform, even spread over the entire lawn.”

Bourne recommends sowing grass seed at a rate of one handful per 0.5 sq m (5 sq ft).

Sow seed on a still day, otherwise the wind might blow it into your neighbours’ flowerbeds!

The seed you use to overseed the lawn should start to germinate after 10 to 15 days.

You can then give the lawn an autumn lawn feed, which will help nurture it through winter and ensure it is ready for action when it comes to growing again in spring.

Autumn lawn feeds, (also often called autumn lawn fertilisers in shops) are higher in potassium than ones you would give the lawn in spring.

The potassium helps build up resilience to the frost and cold. Feeds also help the lawn retain its lovely green colour. They also contain high amounts of phosphorus which helps strengthen their root system and encourage the lawn to knit together. This should help reduce the chances of moss forming in bare areas of the lawn.

Lawns are particularly vulnerable to being smothered by moss at this time of year due to the damper conditions. Also, most grass species tend to stop growing in cooler temperatures, while moss can continue to thrive.

Some autumn lawn feeders contain a moss killer. Look for the ingredient ‘iron sulphate’ on the label which should kill off any moss.

Bourne says: “Using a feed with iron sulphate in it is a good idea in autumn, as it keeps back the moss. It is a preventive treatment, saving you a lot of work the following spring, when you will then have to take action to remove the excess moss.”

However, if you have re-seeded recently, you may need to wait a few weeks before applying an autumn lawn feed containing iron sulphate. Always read the instructions on the label before applying.

Autumn lawn feeds are usually granular and should be applied at the recommended rates on the package. A standard amount would be something like 30g (1oz) per square metre, but do check as products can vary. Never apply fertiliser when frosts are predicted as this can damage the leaf blades.

Bourne says: “If you want the lawn to remain looking good throughout the winter, you can apply this autumn lawn fertiliser every six weeks or so.”

Fertiliser applicators are the most reliable way to uniformly spread fertiliser over the lawn. They are usually a hand-held device which spins or drops out the feed over the lawn at the recommended rate. Or for larger areas a drop spreader on wheels can be used.

For smaller areas, I like to simply measure out the required amount per square metre into a plastic cup. Make a mark on the cup with a pen, and fill the cup up to that mark and scatter the amount roughly over each square metre.