Friday, August 30, 2019

Worm composting at the Windham Farmer’s Market

By Briana Bizier
A handful of visitors to the Windham Farmer’s Market last Saturday ended up leaving with a few new, hard-working pets. One hundred new pets, to be exact.

Jock Robie of Mainely Worm Bins traveled to Windham to teach farmer’s market patrons about indoor worm composting using their kitchen scraps. Unlike traditional composting, which requires an outdoor compost pile, worm composting can be done anywhere by anyone. The results of indoor worm composting, called castings, make an impressive soil amendment. Worm castings contain microbes, fungi, and plant nutrients. When added to soil, they help feed the plants, help the plants resist pests and disease, and stimulate plant growth.

Jock showed the audience several photographs of lettuce, arugula, and high bush blueberries grown in a mixture of potting soil and worm castings. The vegetables that had been grown with worm castings were much larger and lusher than those grown in regular potting soil, and the corn that had been grown in soil amended with worm castings was over seven feet tall!

Worm composting, as Jock explained, is very straightforward. The worms live in damp, shredded newspaper in a large bin. Once a week, the worms are fed a quart of kitchen scraps. want to feed your worms a balanced diet,” Jock explained. Any fruits, vegetables, and even faded flowers are fair game, although worm owners will want to avoid meat, fish, or dairy, as those can be smelly. The worms even enjoy coffee grounds and coffee filters, but they can’t digest eggshells unless the eggshells have been pulverized in a blender or food processor first.

As Jock explained what meals the worms enjoy, he showed a picture of a small jack o’ lantern in a worm compost bin. After several weeks, the pumpkin had been reduced to a pile of dark, nutrient-rich
worm castings.

Who would have thought those little things could eat so much?” an audience member asked.
Lots of the eating is done by microbes,” Jock replied. “Worms don’t have teeth, so the food needs to decompose a little first. Once it’s soft, the worms eat the food and the microbes.”

After three to four months of weekly feedings, it’s time to harvest the worm castings. Jock brought a “ripe” worm composting bin to the Farmer’s Market to demonstrate the harvest procedure. As he described the process, Jock poured a dark, loamy mixture of shredded newspaper, worm castings, and worms through a large metal sifter. Worms and newspaper scraps destined for a fresh bin stayed on top while the worm castings fell to the bottom.

The entire process was surprisingly clean and odor-free. This journalist is relieved to report that worm castings look, and feel, exactly like dirt. But they pack a powerful fertilizer punch, even for houseplants. The castings can be mixed directly into soil, or they can be combined with water and aerated to make “worm tea.”

Also, unlike traditional outdoor composting, worm composting runs happily throughout the long Maine winters. Jock reports that he has sixty worm bins in his cellar, creating compost throughout the year. When asked how many worms you need, Jock replied that you can have as many or as few bins as you’d like.

What you produce in your kitchen is enough for your own kitchen garden,” he explained.

After watching Jock’s presentation, my two little assistants were very excited to help make their own worm composting bin. This began with a wooden trellis at the bottom of a large, plastic crate to keep the bin from becoming too wet. Then, my assistants added about two pounds of dry newspaper on top of the trellis to absorb excess moisture. After that came the “bedding;” shredded, damp newspaper that had already been in worm bins for three to four months.

This is the worm furniture,” Jock said. “Worms don’t like light, and they don’t like to be dried out.”
After adding the bedding, my assistants helped Jock open a bin of one hundred squirming worms. 

While this writer was envisioning a mess of slimy night crawlers, our usual choice for fishing with worms, composting worms are actually very small and a dull red color. They typically live in decomposing leaves on the forest floor.

They look like nails,” Ian, my five-year-old assistant, declared. “Only without the flat part on the top.”

Sage, my eight-year-old assistant, agreed that these worms are, “totally not gross.”

Once our hundred new pets had settled into their shredded newspaper “furniture,” we helped Jock add a quart of kitchen waste, which included onions skins, orange peels, coffee grounds, and wilted flowers now destined to become worm castings for our garden.

As the hundred tiny worms squirmed down between layers of damp newspaper, we covered the worm bin with a layer of plastic bags to lock in moisture and dry newspaper to block the light. A row cover across the top of the bin helps to prevent fruit flies, another decomposer who would be much less welcome in our kitchen. Jock promised to contact me in three to four months to help with my first harvest of the worm castings, and my assistants helped me carry our new worm composting bin to the car.

This is amazing!” Ian declared triumphantly.

I had to agree.

If you’re interested in worm composting, you can find Jock’s blog at:, or you can contact him directly at:

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