A Worm Farmer Explains Nature’s Most Effective Fertilizer & Plant Food

An unusual farmers' market booth had me wondering how in the world one wrangles a worm, and why they would want to in the first place

Lucy Wheeler
photography by
Lucy Wheeler
February 24, 2020

All I could see on the table were different sized bags of what looked like dirt. There wasn’t a worm in sight, despite the sign draped over the table that read: Rubi “The Worm Wrangler.” “Worm castings are the richest natural fertilizer known to humans,” Rubi says, seemingly reading my questioning mind.

She goes on to explain that worm castings stimulate plant growth more than any other product on the market and can be used as an ingredient for potting soil (as plant nutrients) for plants, trees, vegetables, shrubs, or flowers.

When used as mulching material, worm castings ensure minerals are absorbed in the soil, and because it doesn't burn plants, you can use as much as you'd like.

“It’s black gold,” Ruby grins. “I just put it on my roses and get out of the way.”

I purchased a bag of the worm castings and did just that. The results were incredible, and my curiosity grew as rapidly as my roses. I returned to the market to learn more about Rubi and her journey into the world of worm farming.

All her life, Rubi loved horses and gardening, and after her children finished high school, she began managing an Arabian horse farm.  After 15 years, she decided to start her own horse boarding acreage where she could do more gardening while working with the horses she loved.

She boarded, fed them, and cleaned up after 18 to 20 horses, leaving their owners with the responsibility of exercising them, while she renewed her passion for gardening and garden maintenance.

Maintenance, to Rubi, went beyond weeding and pruning, extending into soil improvement. She set up a small worm composting box in hopes the wriggly creatures would boost production. She quickly realized that the worms had far more influence on her garden than she had expected.

She found a man in Granada Hills who sold worms and rather impulsively purchased 25,000 Esenia Fetidin Red Wiggler worms, one of the seven species of earthworms out of 9,000 that are suitable for vermicomposting.

Then she went home and did the math. "Worms eat their weight in food every day, lay eggs every ten days, and reproduce themselves every 30 days,” she said, laughing in retrospect. “Feeding the worms required increasing the number of horses.”

Over the years the windrows of her worm farm, with their umpteen zillion worms, have multiplied. Though Rubi’s original plan was to sell the worms, she discovered the real benefit was in the worm castings, not in the resale of the worms themselves.

“It’s a 100% organic food for plants and when added to soil or potting mixes, improves the soil’s structure. It’s more humus than most compost or garden soil,” Rubi explains, her enthusiasm accelerating as she talks about the benefits of worm castings in our environment economically, environmentally, and functionally.

“The castings increase the water retention in soil, assists in soil aeration, and also help keep plant nutrients that would otherwise leach away with water. Organic matter feeds soil microorganisms that produce, store, and slowly release plant nutrition. Earthworm castings suit all indoor and outdoor gardens.”

Each week at her farm, Rubi digs and feeds 180 gallons of worms and worm casting like a kid playing in a sandbox.

The worms are then placed in a harvester, which is used to separate the worms and castings into separate 30-gallon containers under the harvester. The worms are returned to their earth windrow to perpetuate their cyclical growth, while the castings are packaged in 2-pound, 5-pound, 10-pound, and 20-pound packages to be sold at the Vista Farmers' Market on Saturdays and the San Clemente Farmers' Market every Sunday.  

She loves discussing vermicomposting with friends and customers, whether selling live worms, assisting with the start of a small compost, or merely swapping stories about gardening experiences.

Her advice remains the same for every new customer, as I tend my own plants, it echoes in my ears: “Put the casting on there, and get out of the way.”

Find Rubi at the Vista Farmers' Market every Saturday

Rubi’s Tips for Growing with Worm Castings

For Germination

Use 20 worm castings with sand as an excellent germination mixture. This mixture can maintain a continuous growth for about three months without the need for any other plant food.

As a Soil Conditioner

When you hoe a layer of soil, add a layer of worm castings and give it some water.

As a Fertilizer

Sprinkle worm castings around the base of plants and then add water. Worm castings do not burn or damage plants.

As a Liquid Fertilizer

Worm castings can easily be mixed with water. Use 1 cup worm castings for every gallon of water and wait one week. This liquid mixture is an excellent fertilizer or leaf spray. It also helps to control insects.

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