As we look ahead to the end of a long and cold winter, you might notice small, coiled mounds of soil appearing on lawns. These are worm casts, a natural by-product of earthworm activity. While these muddy heaps can be a nuisance on manicured lawns, they’re also a sign of a healthy garden ecosystem.
But what exactly are worm casts, and why do they start to become more noticeable in early spring? And, perhaps most importantly – what can you do to treat or prevent this unsightly issue? Cheryl Harper, MD of Greensleeves Lawn Care, shares all you need to know.
What are worm casts?
Worm casts are the small piles of soil that earthworms leave behind as they process organic material underground. The main culprits are species like Aporrectodea and Lumbricus, which live in permanent burrows and contribute significantly to soil health. By digesting plant debris, these worms enrich the soil with essential nutrients such as nitrogen, phosphorus and potassium.
While their activity benefits the soil, the resulting mounds can become an issue on well-maintained lawns – especially those kept short for ornamental purposes. If left unchecked, these casts can smear underfoot or when mowed – creating the perfect environment for moss and weeds to thrive.
When are worm casts most prevalent?
Worm activity reaches its peak during the cool, damp conditions of autumn and early spring. During these seasons, the combination of mild temperatures and moisture draws worms closer to the surface – resulting in an increase in visible casts.
In contrast, worm activity slows during the extremes of hot, dry summers or freezing winters when worms retreat deeper into the soil. However, as early spring approaches, warming soil and frequent rain often lead to a noticeable surge in worm casts – a sign of nature’s underground workforce busy at work.
Managing worm casts on lawns
While there’s no way to eliminate worm casts entirely, there are ways you can manage them effectively.
Brush them off
Once worm casts dry, they crumble easily and can be dispersed without much effort. Use a soft rake or a stiff-bristled brush to gently sweep the mounds across your lawn. Timing is crucial, however, so wait for dry conditions to avoid smearing the casts, as this can lead to soil compaction and an uneven lawn surface.
Raise your mowing height
During peak worm activity in early spring and autumn, cutting your grass slightly higher can help reduce the visibility of worm casts. Longer grass is more forgiving, as it minimises the impact of mowing over moist casts – helping to maintain your lawn’s even appearance.
Reduce organic material
Earthworms are naturally attracted to areas rich in decaying organic matter. By promptly removing fallen leaves, grass clippings and other debris, you can make your lawn less appealing to worms – reducing the frequency of surface casts.
Aerate your lawn
Compacted soil can force worms to surface in search of oxygen, increasing the appearance of casts. Aerating your lawn helps alleviate compaction by creating small channels that improve drainage and oxygen flow. This not only encourages worms to stay below the surface but also enhances your lawn’s overall health and resilience.
At Greensleeves, our professional aeration services can help your lawn thrive while minimising the impact of worm casts. By addressing compaction and promoting healthy grass growth, we can keep your lawn looking its best year-round.
Prevention strategies
For longer-term management, subtle adjustments to your lawn’s conditions can reduce worm activity.
Soil pH adjustment
Earthworms prefer neutral to slightly alkaline soil, making these conditions ideal for their activity. By slightly acidifying your soil using products that contain sulphur, you can create an environment that is less appealing to worms – reducing their presence on the surface.
Greensleeves’ trained professionals can recommend safe, tailored adjustments that suit your lawn’s specific needs, ensuring effective results without compromising grass health.
Watering practices
Moist soil attracts worms, encouraging them to surface and leave casts behind. By reducing watering frequency and ensuring proper drainage, you can make your lawn less inviting for worms while still supporting healthy grass growth.
With Greensleeves’ seasonal lawn treatments, you can optimise your lawn’s water retention and drainage. These treatments not only discourage worm activity but also promote lush, vibrant grass, ensuring your lawn stays healthy and visually appealing whatever the season.
It’s important to remember that worms are an essential part of a healthy garden. Instead of viewing worm casts as a problem, consider them a sign of vibrant soil life. By adopting simple management practices, you can maintain a beautiful lawn while reaping the benefits of these underground allies.
For further information about Greensleeves and how they can help you with your lawn care, visit www.greensleeves-uk.com