A Happy Kingdom of Worms – In Your Kitchen


September 5, 2015

HomesteadIssue 14: September/October 2015

Her long braids bob merrily as Linda Leigh circles the demo box, spraying water on the cloth that covers the featured performers, a couple hundred wiggly worms.

“They are too dry,” she tells an early customer at the Heirloom Farmers’ Market at Rillito Park. “Their skin has to be moist for them to survive.” Worms breathe by the diffusion of air through a moist coating on their skin, Leigh explains.

Every few minutes, a visitor or two stops to look in on the pinkish-to-multicolored worms. With Leigh’s help, they turn back the cloth and dip their hands into the black humus to lift a glob of wormhood, as if to wish them a good morning.

These worms do feel friendly as they crawl about your hand. Nothing creepy about these guys, the all-stars of Leigh’s five-year-old Vermillion Wormery in Oracle.

It’s just past 8 a.m. on a summer Sunday and Leigh (rhymes with day) has already been delivering minilectures for a half hour, almost nonstop, to passersby. It’s what you’d expect from the former college teacher and lifelong researcher.


Linda Leigh of Vermillion Wormery.

Leigh was an original crew member living in the Biosphere 2, 30 miles north of the market. Before she moved into the Biosphere 2, in 1985, Leigh worked as its biome design coordinator, working alongside specialists in all aspects of building food webs—experts in worms, soil, butterflies, as well as engineers and architects in the design of the rainforest, savannah, and desert. She was eventually selected as one of eight Biospherians chosen to “walk our talk,” and lived inside Biosphere 2 from 1991 to 1993. While inside, she managed those wilderness systems, and worked daily in the agriculture system with the other Biospherians.

“We grew most of our food during that time and of course recycled all of our ‘waste’ … well, really no such thing as waste in a truly closed system, is there?” she recalls.

Before becoming a worm entrepreneur, she also worked for the Nature Conservancy and at the research department of the Arizona-Sonora Desert Museum to identify, collect, and grow desert plants that could be appropriate for drylands agriculture.

A lifelong student of botany, a few years ago, Leigh hit on a new mission: creating a world with less organic waste. She returned to worms, those wrigglers who love to eat extra bits of lettuce or orange peel and excrete what becomes a gardener’s gold. She says that adding vermicomposting to gardening was a natural process, completing the total systems cycle that she loves to practice and study.

“Spreading the worm,” as Leigh calls her work, came serendipitously. A neighbor was getting married and had to ditch her worm bin for marital harmony. Leigh took over. She failed, the worms bailed, and she began studying. “I learned from the ground up,” she says. It helped that she had a Ph.D. in systems ecology and energy analysis from the University of Florida.

As Leigh buzzes about her booth, more customers line up for a quick tour of the worm bin, or to buy some small Egyptian spinach starters or a few herb plants. Some will buy a bag of worms or just the dark fertilizer, called castings.


Worm castings make for gardener’s gold: nutrient-rich soil.

Leigh studies each potential customer to see if they have the necessary character to take some of her worms away. “That’s why I vet people,” she says with a laugh. “I don’t want my worms going home with just anybody. I want only those who will be faithful stewards. Starting a worm bin has a pretty strong learning curve.”

Mainly, they have to remember to keep the bedding, a mix of shredded cardboard and coconut coir, or fiber, moist, but not too moist.“I won’t send my worms home to their death in the wrong environment,” Leigh says.

“Why start a worm bin?” asks a potential customer.

“To get rid of your garbage and improve your plants,” Leigh says.

But one customer has his own view.

“They become like my pets,” says Donald Lockwood, a massage therapist, who came to the farmers’ market with his wife, Charity Whiting, and daughter, Ruby Rain. They buy a bag of worms to restart their bin. Their first experiment failed. “It was a disaster. They all died,” says Lockwood, who vows he’s learned enough to start again.

“You get really bonded with them. It makes you happy to toss in your food scraps and have them poop out this great fertilizer,” he says. “We water all our plants with the mix of castings and water, what we call compost tea.” Their compost tea is made with one cup of worm compost per gallon of dechlorinated water, plus 1 teaspoon of unsulphured molasses, stirred periodically for least 24 hours to keep it oxygenated.

Another lesson to be learned is heat.

This morning, the temperature is on its way to 109. But in the shade, Leigh’s worms are no more than 75° to 80°. Leigh explains that the worms can survive anywhere as long as their bedding is between 34° and up to 88°. But they are happiest between 60° and 75°.

At the Vermillion Wormery site in Oracle, Leigh and her business partner, Doug Shepherd, have built eight 4-by-8 feet concrete bins and few others made from wooden pallets, all sunk about a foot into the ground to provide some insulation from heat and cold.

She uses horse manure, food scraps from friends and restaurants, coffee grounds, and shredded paper to grow worms for sale. The horse manure has too much sand to be ideal for her marketed castings; for that, she uses llama, sheep, or goat manure. Leigh looks over at the Adventure Coffee Roasting booth. “I take all their grounds home to the worms,” she says.

Just then, a UA student arrives, seeking advice. “I’d like to know whatever I need to know to get started,” says Emily McIntosh, just back from the Peace Corps in Mozambique. Ten minutes later, she knows. She places an order for a quarter pound of worms, for $6.25. Delivery next Sunday.

She passed the test.

“I’m so excited,” Emily says, before she departs.

Worms will eat everything from food scraps to coffee grounds.

Worms will eat everything from food scraps to coffee grounds.

So you bought worms. What next?

The bin

To prepare your 10-gallon bin for a pound of worms, drill 3/8-inch wide ventilation holes in the bottom, upper edge, and top of the bin. Keeping it indoors works best in extreme summer or winter temperatures. Worms are happiest, and eat and reproduce more, between 60 and 75 degrees. If you are managing the worm bin correctly, there should be no smell and no invasive critters.


Vermillion Wormery mixes compost and coconut coir, which can hold a lot of water. The compost kick-starts the microbial community to start breaking down the food you put in so that the worms can eat it. To test for the correct amount of moisture in the bedding, take a handful (without worms) and squeeze it as hard as you can. A few drops of water should come out. If it’s too dry, mix in some water. If it’s too wet, add some shredded paper or cardboard.

Adding the worms

Place the worms and the material they are packed in on top of the bedding in the bin. Watch them wiggle down into the bedding—they will move away from the light into the dark bin. Lay shredded paper on top of the bedding and worms. Moisten the paper—it will keep your bin cool in the summer and help maintain the moisture level. Worms will eat it eventually, so add fresh shreds and new bedding now and again.

For the next night or two, your worms might be a bit restless in their new home. Leave the bin in a place with a light turned on (in a bathroom, say, or laundry room) and the bin top removed for the next two or three nights so they won’t be tempted to explore outside the bin. Start feeding them food scraps in a few days, after they’re settled in. Using compost as part of the bedding offers plenty of food for a few days before you start your regular feedings.

Feeding the worms

Your worms will eat food scraps, coffee grounds, shredded cardboard and paper, compost, and other organic materials. They don’t eat soil or anything that is not organic. Don’t feed them dairy or meat, which will become stinky. Chopping and freezing food scraps before feeding them to worms increases the surface area of the food for microbial growth, breaks the cell walls of the plant, and kills fruit fly eggs and larvae that could be a problem later.

Start with a light feeding, maybe a cup or so, and bury it an inch or two under the surface. Cover it with bedding. Once that food has been consumed, feed them more. If you have a 10-gallon bin, you can typically feed your worms up to a half pound of veggie scraps a day. You can add a tablespoon of ground eggshells or fine sand to help the worms grind the food. It’s best to not feed a lot of any one particular food at a feeding.


The worms will let you know when to collect the castings. When all the contents of your bin look like dark coffee grounds, it’s harvest time. Using the dump-and-sort method, dump the bin contents on a flat surface where a light, or the sun, can shine on them. Make little piles of castings and wait a few minutes until the worms burrow down away from the light. Brush the castings away until you have a pile of castings and a pile of worms. Harvest your castings, and have a bin with fresh bedding ready. Put the worms in it, and start all over again.

Using worm castings

Seedlings: Use up to 20 percent worm compost in your potting mix. More than 20 percent will not harm plants, but it won’t offer much additional benefit.

Vegetables and annuals: Side dress with about ½ cup of worm compost per plant as needed.

Transplants: Provide 1 inch of worm compost in planting hole before placing plant.

Potted plants: Mix 1 inch of worm compost with top of soil around base of plants as needed.

Trees and shrubs: Mix 1 inch of worm compost with top of soil around base of plants every month during growing season.

Worms will eat everything from food scraps to coffee grounds. ✜

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