Worms are hermaphrodites, each one containing both male and female parts. A worm can lay more than a thousand eggs in a year and can live for several years.

Earthworms can be divided into three types:

Litter dwellers live in the decomposing layers in wooded areas.

Soil dwellers randomly work the top foot of soil, digesting whatever organic matter they run into.

The deep-burrowers (night crawlers) travel down several feet into the soil. Deep burrowers go to the surface to leave their castings in piles and pull organic matter down into their burrows with them. These are the worms that make the lawn bumpy.

What happens to worms during the winter? No matter what kind they are, they will either travel deep enough to go below the frost line or they will find someplace warm like a compost pile to spend the winter.

The Good
Speaking about worms, Charles Darwin said "It may be doubted whether there are many other animals which have played so important a part in the history of the world as have these lowly, organized creatures."

Earthworms are incredible. They process waste, aerate the soil and produce fertilizer. Nothing is more important to the process of keeping the soil friable than worms. Their action essentially plows the soil, helping with air and water penetration and breaking up compacted areas. In healthy soil, worms can create over a thousand tunnels in every square foot of soil. These tunnels can actually be used as channels for roots, as well as pathways for moisture and air in the soil. Worms eat by taking in a combination of organic matter (leaves, dead grass, etc.) and soil. As organic material and soil is passed through their digestive systems, it is enriched and inoculated with millions of beneficial bacteria. The end result is rich in nutrients in a form all plants can use and has a neutral pH. That same soil the worm consumed now contains 5 times more nitrogen, 7 times more phosphorus and 11 times more potassium, plus all the beneficial bacteria. Best of all, worms not only produce fertilizer; they spread it for us.

Worm manure, which looks like light colored coffee grounds, is referred to as castings. Believe it or not, a worm can produce its weight in castings each day. Lawn thatch control is also aided by worms. When worm castings are left on the surface of the soil, they add the nutrients and bacteria needed to speed up the decomposition of thatch. Some worms actually take some of the thatch into their burrows and digest it there. Vermiculture is the practice of worm composting and vermicompost is the result. There are kits homeowners can use to have worms compost all their household plant scraps indoors year round. Worm composting is done with special varieties of red wiggler or long gray worms. Tests are currently underway to discover how to best use this renewable earth-friendly compost product in the greenhouse and nursery industry. Preliminary results show adding vermicompost to potting mix may reduce the need for fungicides.

The Bad
Worms can cause a lumpy lawn. Even though the lumps are seasonal (early spring and again in fall) and temporary, they can be distressing. The lumps are technically called "middens" and are made up of earthworm castings and plant residue. Worms create the middens to cover the opening of their burrows. Middens will dissolve and actually help fertilize the lawn if they are left alone. To hurry the process, they can be raked to break them up either with a hand rake or a power rake set high. Despite all the great benefits of having worms in the lawn and garden, sometimes we get questions about how to control them. Worms are sensitive to quite a few insecticides and even some fungicides, but there are not any chemicals specifically labeled for this purpose. In the past, Diazanon was used, but it has been determined to cause too many problems and has been pulled from the market for homeowners.

Nature's Concerns
Studies are underway to gain a better understanding of what looks like a serious problem caused by worms in heavily wooded areas. Apparently, there are too many worms (non-native varieties) and they digest the layer of decaying forest floor litter too quickly. Normally the natural bacteria, fungi and native worms would take 3 - 5 years to decay a years worth of matter. In areas where there are lots of non-native worms, (mostly night crawlers) the fallen organic matter is being digested in less than a season. It is a problem in that this leaves areas of the forest floor essentially bare, opening them for erosion and changing the ecological balance. Another facet is that this rapid digestion also means a rapid infusion of nutrients. This may sound like a good thing, but nature is very complex. A change in part of the ecology may favor certain species over others and change the balance over time. Scientists are also trying to determine if this increase in nutrients will cause changes in the concentration of mycorrhizae (microscopic beneficial organisms) in the soil. Generally the research indicates that the larger the population of worms in an area, the fewer the number of species of plants, which may indicate fewer mycorrhizae.

Encouraging Worms
Soils high in organic matter usually have lots of worms. According to the National Soil Tilth Lab in Iowa, the keys to encouraging worms are:

- Using fewer pesticides (both insecticides and fungicides)
- Using organic mulches
- Keeping the soil moist and avoid tilling it.

They also advise either using organic fertilizers or splitting synthetic fertilizers into several smaller applications.

Additional Bachman's Information
Dethatching and Aerating Lawns
Renovating a Lawn
Fertilizing Your Lawn
Bachman's New Lawn Fertilizers
Earth-Friendly Solutions in Gardening

©Bachman's 2007