Home & Garden

Worm composting, or vermicomposting, is good for your garden and easier than you think

Rhonda Sherman, an extension specialist at N.C. State University, is a vermiculture and vermicompost expert. Sherman is also the president of the NC Composting Council.
Rhonda Sherman, an extension specialist at N.C. State University, is a vermiculture and vermicompost expert. Sherman is also the president of the NC Composting Council. jleonard@newsobserver.com

A chance encounter recently with a WUNC radio show called “Dream Jobs” drew my focus to a gardening practice that hasn’t lately been on my radar – vermicomposting.

The show featured Rhonda Sherman, who I learned is on the agricultural extension roster at N.C. State University and is one of the world’s leading experts on making compost with worms.

As a wildlife gardener, I know that soil quality can have a big impact on whether plants thrive or struggle. And I know that compost is the most valuable soil amendment because it lacks some harmful properties found in commercial fertilizers, such petroleum products, and it reduces the overall waste stream. By composting waste and putting it back into the soil, each plant gains a greater chance of receiving nutrients to grow and flourish, produce seeds, fruits and flowers and, in turn, provide nourishment for animals.

So why is my compost bin sitting empty in the back yard?

And if I struggle with regular composting, how much more likely would I be to become engaged in vermicomposting?

After talking with Sherman, I can see how composting with worms may truly be a better fit for my lifestyle. Among the reasons are that vermicomposting is quicker at turning food scraps into nutrient-rich soil, it can be done indoors in small spaces, and it requires less oversight than a backyard compost pile.

Another “wormhead,” as avid vermicomposters are sometimes known, is Bentley Christie, a California-based organic gardener who started his CompostGuy.com blog 15 years ago after becoming hooked on vermicomposting.

His website is a great resource for novice composters who want to learn more about both the traditional and worm-based processes, as I do.

Traditional composting uses microorganisms present in the soil to process organic materials, creating a nutrient-dense compost to put back into the earth.

In traditional composting, food scraps are “cooked” via the heat generated by microbes going about their work in breaking down the materials. The process depends on the size of the compost pile, a specific carbon-to-nitrogen ratio, moisture content, and aeration. At least a cubic yard of materials are required – but more is better.

As the pile heats up to 140 degrees or more, the weed seeds and pathogens in the compost are killed. A well-tended compost pile continues to cook even in cold weather.

On the other hand, a large compost pile can be labor intensive. Organic materials for the compost pile must be gathered, piled and then turned on a regular basis. Some beneficial microbes die in the heating process and nitrogen is depleted.

Vermicomposting creates a similar product, but can be conducted on a smaller scale. For household use, it’s easy to purchase or make a worm bin. The bin size should reflect the amount of food waste generated. For example, a family of two generating a half-pound of food waste per day would require a two-by-two foot bin. A handy how-to on making the bin is at diynatural.com/vermicomposting-worm-farm-diy-easy-and-frugal.

Other elements include shredded paper and worms. Certain species of red worms are considered best at composting. A Google search will turn up a variety of sources.

Composting with worms doesn’t require heat. In fact, it works best between about 60 degrees and 85 degrees F, so it often takes place indoors. Less nitrogen is lost in the cooler process but weed seeds and such may not be killed.

The CompostGuy recommends both methods, and uses them together: “By ‘pre-composting’ then vermicomposting waste materials you can get the best of both worlds: Pathogen and weed seed destruction of hot composting (without too much nitrogen loss), followed by fast processing by worms and production of high quality vermicompost.”

Now back to Sherman and her dream job.

A specialist in solid waste management – a.k.a. trash – she came to North Carolina from Michigan as the recycling coordinator for UNC Chapel Hill and began working as an extension specialist at N.C. State in 1993, where as a faculty member she was told it’s “publish or perish.”

In response, she designed seven fact sheets addressing topics related to recycling. Her big hit was “Worms Can Recycle Your Garbage.” It’s still being reprinted today.

“That one small publication changed my career,” says Sherman.

Since 2001, she has organized annual conferences on worm farming and composting that have been attended by representatives from 23 countries and 27 states. There are, she says, schools, hospitals, food canning and processing plants, food banks, restaurants and other institutions all around us doing vermicomposting.

“People are more aware that food waste is a problem,” Sherman says. “It shouldn’t go into the landfill or down the drain.”

She notes that while food waste makes up only 14 percent of the waste stream, it is No. 1 in what makes up a typical landfill. (Paper is the largest segment of waste generated, but thanks to recycling it is the third most common component in landfills today.)

If you are worried about food waste but don’t want to compost it yourself, there are collection companies in the state that will pick it up for use in composting. Check out compostnow.org for resources on food waste collection as well as composting.

Sherman notes that household vermicomposting produces a greater array of microorganisms than is present in traditional compost, as well as humic acid, fulvic acid and plant growth hormones.

Repeated studies have shown that plants treated with vermicompost produced significantly more flowers and fruit than those raised using regular compost or commercial nutrients. To me this is a big plus, evoking images of a bountiful kitchen garden next spring, along with healthier plants for supporting wildlife.

Sherman agrees with Christie – that both vermicomposting and regular composting have numerous virtues that cannot be replicated through commercial additives. Composting is pretty much a man-made process, yet it works with nature, rather than against it, and supports healthy biodiversity.

“It’s a true recycling process,” she said. “It takes water and nutrients to make food, then we take it out of the ground, removing those resources. By composting, we are returning those things to the earth.”

Reach Elder at wildlifechatter@gmail.com.