how-to-get-rid-of-worm-casts-on-your-lawn

How to Get Rid of Worm Casts on Your Lawn

Although they’re not the worst thing to find in your garden, worm casts can ruin the aesthetics of a well-manicured lawn; plus, they can introduce weeds which is definitely not what we want. But, on the flip side, there are also many benefits to having worms around!

This article explores what causes worm casts and why they can be problematic. We’ll also discuss why you maybe shouldn’t be so quick to get rid of them.

Of course, if you still aren’t convinced, we’ll also cover how to get rid of worm casts completely. 

What Are Worm Casts? 

Simply put, worm casts are worm poop. Worms consume soil in order to extract the organic matter within it. Then, they excrete the soil, expelling it onto the ground surface. This creates swirls of mud, otherwise known as worm casts.

Also, you know that slimy appearance they have? Yeah… that’s the worm’s digestive enzymes. Yum.

what-are-worm-casts

In the UK, there are three species of worms that cause casts:

  • Common (or lob) Worms (lumbricus terrestris)
  • Black-Headed Worms (aporrectodea longa)
  • Grey Worms (aporrectodea calignosa)

As you can probably guess from the name, the Common Worm is the species most frequently found in UK gardens.

Worm casts can become a lot more pronounced from September to October, as worms love cooler temperatures and rainy days. Worms pop up on wet ground surfaces (typically during the night) to eat, breathe, and reproduce. And, of course, they leave their casts behind.

The Problem With Worm Casts

The main problem with worm casts is their appearance, especially on the lawn. They can be a bit frustrating – you might spend hours maintaining your lawn one day, only to come back the following day to find worm casts everywhere!

If you keep the grass relatively long, you may be lucky. Worm casts don’t show up as easily amongst longer grass. However, if you keep your grass short, they might be pretty obvious! 

Not only can worm casts look ugly, but they’re also difficult to remove. It can be incredibly vexing trying to get a worm cast off your lawn – they often get smeared instead (which can look even worse!).

Another complication of worm casts is weeds. Weeds love empty spaces. They’ll pop up wherever they can, and they particularly like nestling themselves in between your grass seeds. When worms expel the soil, they leave a gap between grass seeds. This gap is ideal for weeds.

So, first things first – how can you make sure your problem is earthworms and not something else?

the-problem-with-worm-casts

Spotting Worm Casts

By checking the appearance of these muddy deposits, you can tell the difference between worm casts and ant mounds, moles, and mining bees. Worm casts usually form a cylindrical, coiled shape and have a distinctive muddy look. 

You’ll know you have a problem with earthworms if you can regularly see these casts springing up on your lawn. You’ll also be able to see the holes left behind on wet days. They’re usually around 6 mm in diameter. 

On occasion, you may even spot the red-brown earthworm doing its business. These worms live in the top part of the soil and can grow up to 200mm in length. Adult worms have a thick band at the upper end of their body. So keep an eye out! 

Benefits of Lawn-Loving Worms

Yes, worms can be a nuisance, but they actually do a lot of good for your garden. They naturally improve the soil, making it better for your beloved plants. 

benefits-of-worm-casts

So, what are the benefits are having worms around? Well…

1. Worms increase soil aeration & improve soil structure

As worms eat the soil, they create little pockets of air throughout. This improves the soil structure as it aids the movement of water, oxygen, carbon dioxide and nutrients underground. All of these goodies are then available to your grass. Without worms, the job of aerating the lawn falls solely to you!

2. They maintain the grass and prevent diseases

Lawn thatch is the yellow layer of organic matter that accumulates underneath the green bits of your grass. It’s not popular amongst gardeners – for starters, it can cause grass to turn yellow. Helpfully, worms eat lawn thatch as well as soil. They also consume dead roots and leftover grass clippings. All these things help with grass health.

Lawn thatch can cause grass to suffer from diseases. For example ‘Dry Patch’ and ‘Type 2 Fairy Rings’. These can cause a lot of damage, but worms help diminish the effects of these, too.

Without worms, you’ll need to spend more time de-thatching the lawn yourself. That might mean getting the scarifier out more often to avoid this build up of organic matter.

3. Worms enhance nutrient accessibility

Turns out, worm casts are incredibly nutrient-rich. This is because the digestive enzymes that are released through excretion concentrate the nutrients. In fact, worms release more nutrients than they consume – up to 11 times more! 

Only a tiny portion of worm excrement ends up as casts. The rest stays in the soil. This makes nutrients more accessible to the grass. Therefore, worms are doing us a real service – your grass will certainly be grateful for all of the extra nutrients! (Plus, you may find you don’t have to apply lawn feed as regularly!).

As you can see, there are a lot of benefits to keeping worms and their worm casts around.

Worm Cast Removal Methods

If you’re still set on removing worm casts, two methods work best:

worm-cast-removal

1. Pick up and toss

Pick your worm casts by hand and toss them onto the compost bin. Your compost will benefit from the nutrient-rich soil.  For more tips on making compost at home, check out our ultimate guide to composting!

2. Sweep or pick up and scatter

When worm casts are dry, they can be swept across the ground or broken up and scattered. This makes them less visible whilst keeping the nutrients available for your grass. You should try to avoid using your lawn mower whilst waiting for worm casts to dry – this will lead to the casts getting squashed into the grass.

Worm Cast Control Methods

Still wondering how to stop worm casts? Well, first you have two options – go organic or use chemical control. We’ll start with the organic route.

Natural Control Methods

1. Let your grass grow

Allowing your grass to grow longer will make worm casts less visible. They won’t be gone, but you won’t be able to see them! Some mowers offer a higher cutting height than others (like the best lawn mowers for long grass) which makes worm casts easier to conceal.

2. Reduce the prevalence of lawn thatch

By getting rid of lawn thatch, you eliminate a vital source of food for the worms. This will make them less likely to hang around on your lawn. 

Scarifying the lawn is the best way to remove thatch. Check out our article on how to use a lawn scarifier to make sure you don’t damage your lawn!

3. Remove dead leaves and grass clippings

This takes away another essential food source, also reducing worm numbers. They won’t hang around for long if there isn’t any delicious grub!

4. Ditch watering, organic fertilisers and compost

However tempting it may be to water the casts away – stop before you do! The wet ground makes worms come up to the surface – they love a bit of ‘rain’ and it’ll only encourage more casts. 

Similarly, worms love themselves some organic fertiliser – compost will keep them content for days!

If you’re watering often, or using a lot of nutrient rich compost (which certainly has its benefits – take a look!), you’ll be encouraging worms to stick around.

5. Maintain your lawn through top-dressing

Keeping to a yearly lawn maintenance plan is a great way to lessen the effects of worms on your lawn. We’ve written a month-by-month guide of how to best care for your lawn – check it out for some useful advice.

Using a top-dressing with a high concentration of sand will diminish the lawn’s moisture and make the ground less appealing to worms – so it’s a potential route to consider. If the mention of sand sounds strange, you may be interested to learn that using lawn sand actually has a range of benefits!

worm-cast-control-methods

Chemical Control Methods

As I mentioned above – there are some chemical methods that can also be used to limit the number of worm casts.

Iron sulphate is a worm cast treatment that increases the acidity of the soil. Worms hate acidity! Applying an iron sulphate solution every couple of months will cause worms to burrow deeper, leaving your grass free from casts. Use lawn sand for spring and iron sulphate for autumn. Your grass will look greener as a result, too! Iron sulphate is often found in a lot of moss-killing lawn fertilisers.

The other chemical approach is to use a worm suppressant. There are several worm suppressant products on the market like Cast Clear or NutriFlo Casting. These products contain certain nutrients that worms don’t like, so it deters them from sticking around. Make sure the product doesn’t harm worms and instead only deters them – they’re still valuable creatures after all!

Worms – Friend or Foe?

So, there you have it – from the benefits of having worms in the garden, to the methods of keeping them away – we’ve covered it all!

Ultimately, it comes down to this simple conclusion: if you want worms in the garden, you may have to put up with worm casts – growing longer grass can help disguise them. If you don’t want any worm casts, you probably need to deter worms from sticking around.

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