Our 5 top autumn lawn care tips

As temperatures take a dip and the growth of lawns slows up, we look at how to give your grass some TLC before the onset of winter.

Autumn lawn care tips are important because they helps strengthen the grass and build its resilience for the colder winter months. The season is a time for lawns to recuperate after the intensity of summer.

Over the past few months our lawns will have been through a tough time, dealing with droughts or perhaps excessive growth if temperatures and moisture levels have been high.

The lawn may also have taken a battering from people using it more in the summer, causing compaction issues and general wear and tear.

Why autumn lawn care is important

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, over-seeding and feeding.

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

1. Scarify your lawn

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.

Thatch needs to be removed because it smothers the surface, preventing the grass from knitting tightly together to form a lovely, thick sward.

It’s at its maximum depth in autumn, after a season of mowing grass, and can prevent moisture from reaching the roots of the grass – making it susceptible to drying out. The thatch 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).

How to scarify your lawn

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 aficionados 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.”

2. Aerate your lawn

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

“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.

3. Top dress the grass

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 over-seed 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.”

4. Over-seed everywhere

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!

5. Feed your lawn

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, which helps build up resilience to the frost and cold.

Feeds also help the lawn retain its lovely green colour, and 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.

How to deal with moss

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.

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.”

Check your type of lawn feed

Bourne also has a warning about using lawn feeds.

“Don’t use your standard lawn feed that you might have been using during the spring and summer.

“These are high in nitrogen and will encourage the grass to grow. You want the grass to start resting in autumn, not start growing again. Make sure you are using an autumn lawn feed.”

How to apply autumn lawn feed

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.

Leaves could kill off your grass

Bourne’s other top autumn lawn care tip is to ensure your lawn is kept clear of leaves for the next few months.

“Rake leaves regularly off the lawn. If you leave them, worms will create worm casts on the surface which will leave patches of soil and leave you with dead areas of lawn.

“Add raked leaves to your compost heap or create a separate pile and allow them to decompose to make leaf mould.

“Leaf mould is a wonderful, free and organic material that you can either add to your potting mix or use as a mulch around shrubs and trees.”