The grey skies and persistent rain gets us all down, but garden creatures such as moles, worms and slugs thrive in wet conditions – in fact they absolutely love it!
Whilst worm, mole and slug activity is generally a sign of a healthy lawn ecosystem, rain and damp conditions triggers increased activity from these garden dwellers, leading to lawn damage, including mole hills, worm casts, patches and thinning grass.
Here, Johnsons Lawn Seed experts share their advice on the signs to look out for and how to treat them:
Moles:
While moles are active all year-round, you will likely notice a significant surge in molehills and surface tunnelling during or immediately after rain for the following reasons:
Signs: Raised ridges and soil heaps (molehills) appearing overnight.
Causes: Moles tunnel through lawns searching for insects and worms. They don’t eat the grass but can disturb roots and create uneven ground.
Treatment:
- Remove molehills and flatten tunnels before reseeding affected areas.
- Encourage moles to move on using humane deterrents such as sonic devices or natural repellents.
- Once activity stops, repair damaged areas with Johnsons Quick Fix, a rapid-establishing grass seed and feed blend for quick, reliable patch repair.
Worms
Wet weather is a primary trigger for earthworm activity, often causing them to emerge from the soil in large numbers.
Signs:
- Small worm casts (tiny piles of fine soil) appearing on the lawn surface, especially in damp weather.
- When wet casts are stepped on or mown over, they smear into “patties”. These smears can smother the grass underneath, leading to small dead patches and thinning of the turf.
- The nutrient-rich, bare soil in a smeared worm cast provides a perfect seedbed for weeds and moss to germinate and take hold.
- Repeated casting over time creates a lumpy, bumpy lawn. This can make mowing difficult and may lead to “scalping” (cutting the grass too short in certain spots).
Causes:
- Worms naturally aerate the soil and improve nutrient cycling – both signs of healthy soil. Casts appear as a by product of their feeding and tunnelling activity.
- Earthworms require a moist environment to breathe through their skin. Rain creates a wet surface that allows them to travel much faster and further overland than they can by burrowing through dense, dry soil.
Treatment:
- Allow worm casts to dry, then brush or lightly rake them back into the grass.
- Avoid using chemical treatments — worms are vital for lawn and soil health.
- Reduce compaction with aeration and avoid overwatering, which can encourage excessive casting.
Note: Regular brushing and good lawn care practices will minimise the visual impact of worm casts without harming these beneficial creatures.
Slugs
Slugs are significantly more active in gardens during wet weather. Because they are roughly 80% water and lack a protective shell, they require high humidity and moisture to survive, move, and prevent dehydration.
Causes:
- Slugs move on a trail of mucus. Rain and high humidity prevent this slime from drying out, allowing them to glide across soil and plants more efficiently.
- They are most active at night and after rainfall. Overcast or foggy days can also trigger daytime activity.
Signs:
- Heavy infestations can leave unsightly, ragged edges and holes in the grass blades.
- Shimmering slime trails visible on the lawn, especially in the morning.
- Sudden thinning, areas where new growth seems to vanish overnight, particularly in damp or shaded spots.
Treatment:
- Johnsons Lawn Thickener is the ideal solution for reviving tired, thinning lawns and creating a denser, healthier sward in record time.
For more details on Johnsons full range of products, visit www.johnsonslawnseed.com