Those Dreaded Winter Worm Casts!
To smooth out worm bumps in lawns, you first need a dry day. In some zones, these are few and far between in the winter, Worm bumps in lawns can be unsightly, particularly in the winter months, when the spirals of digested slimy earth are wet and where they occur very close together.
In summer too, worm bumps can be a nuisance, as, after a shower of rain, the worm bumps get wet and sticky underfoot.
If not cleared away before a very long, hot dry spell of weather, the worm bumps can dry out, and - particularly on clay soils - the bumps can become hard-baked little hillocks which affect the smooth operation of a lawnmower.
Some gardeners fear that numerous hard-baked worm bump areas in the turf will cause the lawn to become patchy, as moss, clover and other weeds will grow there in future, instead of fine grasses.
Spring and Fall are the most likely times for worm bumps to appear, as the weather is milder and wetter then. The worms come up to feed when the temperature climbs a little. The earthworms feed on decaying organic matter and excrete the surplus as slimy soil in worm bumps on the surface.
The best way to deal with worm bumps is to try to remove them when they have dried out a little. Wait for the first few dry, warm days of spring and use a light grass rake to scratch the worm bumps into a dry earth powder that will either soon blow away, or filter harmlessly down into the turf. This could ideally be carried out before the first cut.
An effective technique is to methodically treat the area with a light grass rake in a 'cross-hatch' pattern until the whole area has been fine-raked right down to the soil surface. This technique is known as 'scarifying.'
An added benefit of scarifying the lawn is that the thatch of wet damp moss and the remains of last year's grass-mowing clippings will also be removed, leaving the lawn clean and refreshed and ready for a smooth run with the lawnmower.
Serious 'lawn purists' whose aim is to produce a show lawn fine enough to grace any croquet lawn or lawn tennis match, may not be satisfied with this partial remedy however. Such lawn enthusiasts may want the worm population exterminated all together or at least culled! . In the past such zealots may have resorted to Ph lowering treatments such as sulphur powder in attempt to deter the worms by raising acidity.
Unfortunately, chemical worm-treating agents are now frowned upon for safety and environmental reasons and are even banned in many countries. If, on a show lawn of closely-cropped fine grasses, the worm bumps are a serious blot, then the only recourse might be to consult a qualified landscape gardening professional. These operatives often have licenses to use more powerful chemicals. However, there are safety issues with chemicals and of course, cost issues too.
It is worth remembering at this point that earthworms are worth keeping in the lawn for other reasons. They are a beneficial presence in the soil as their constant mining helps to aerate the earth, and they also digest and recycle organic matter such as dead leaves and moss from the surface. They play an important role in lawn drainage too.
It is possible that for the fine green sward spreading before the gardener in summer he has the worms to thank. A healthy lawn might be worth the headache of a minor worm bump issue that can be safely raked away.
Many thanks to Net_Efekts of Flickr for the worm image!
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