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GARDEN SURROUNDINGS: Worm Castings For A Vibrant Healthy Landscape

By Francesca Filanc for Let's Talk Plants! November 2021.

The author's healthy, vibrant garden in Olivenhain, CA.

Several years ago, a landscape designer friend of mine in the Olivenhain Garden Club, Jan Casado, let our club know that her brother-in-law, a biology teacher at La Costa Canyon High School was making worm castings with his students and they were selling bags to raise money for their department. At the time, I lived on four acres, two of which were garden, surrounded by a lemon orchard. Jan would deliver to me 14 to 20 bags every few months. Unfortunately for us in the garden club, Jan’s brother-in-law retired, and the following teacher stopped making worm castings with students.

Since then, I moved to a smaller property but I still have a large garden by most standards. Being an organic gardener, I am so grateful to the many benefits of gardening using worm castings.

"As an amendment, castings are completely finished and unlike some other creature manures, don’t smell strongly (they smell like forest soil) nor will they burn plants due to too much direct nitrogen. Castings do contain 4% to 5% more nitrogen than your average garden soil, but in a slow-release form due to the mucous the worms secrete as they digest (bait fishermen and most kids know the slime we’re talking about).
Wikimedia Commons photo of worms in a worm bin.

Worm castings make soil more absorbent, making moisture more consistently available to plants and preventing soil from completely drying out.

Worms introduce uncountable numbers of beneficial microbes and bacteria into the finished product, guaranteeing the healthiest soil possible. In addition, castings contain humic acid which aids plant nutrient absorption.

Studies show that germination and seedling growth is improved by planting in worm castings. In short, worm castings are the super food of garden plants.

Worms, as scientists are discovering, can also remove heavy metals and other toxins from soil. This can be especially useful in the reclamation of landfills and other contaminated sites. It can also be helpful in keeping your garden soil first-rate.

Of course, some of this process goes on naturally. There’s nothing more uplifting that turning over spring garden soil and finding a bunch of wigglers making your rich soil richer. You can buy fine quality, OMRI-rated worm castings online and in nurseries, and garden centers and use them for your potted plants or to dress your tomato plants and expect all the benefits.

A lot of gardeners add red wigglers, the composting worm, to their outdoor compost piles once the season arrives. This not only speeds the composting process but add the benefits of worm castings to the final product.

Most fun is to make your own castings at home. Composting your own kitchen scraps, thus keeping them out of the landfill or sewage system (for those of us with disposals) is a small reward in a project that gives you a great soil amendment as well as a fascinating science lesson not necessarily just for kids.

We’re told that vermicomposting is catching on with big city Millennials living in apartment for whom keeping worm bins under the kitchen sink is a badge of pride. Every couple months, they have castings to add to their houseplant containers. I know of one family with a worm bin that has caused problems between their kids over who gets to feed the worms on any given night." - From Worm Castings: Plant Superfood By E. Vinje.

When people come to my garden they want to know what my secret is for few pests and vibrant healthy plants with many blooms. I tell them worm castings are gold for the organic gardener with a myriad of benefits to your garden. As E. Vinje states above, many people like to make their own worm castings and it can be a fun project to do with your kids.

Earthworm castings contain chitin and chitinase. Chitin consists of the exoskeletons of insects. Chitinase is an enzyme that plants can absorb through their roots to protect the plants from pests. Ants will not cross worm castings so the plants will not get aphids.

Healthy Eugenia hedge in Olivenhain, CA, thanks to the regular use of worm castings.

When I notice pests and diseases on my plants or, for good measure, every few months I ask my gardeners to sprinkle worm castings under the plants. You can even use them in potted plants. Worm castings are not a fertilizer. Climate change is releasing more CO2 in the atmosphere. Plants take in CO2 at night and this is causing plants and trees to bloom more and to grow extra fast. Have you noticed yourself or your gardeners having trouble keeping up with trimming and pruning? As an organic gardener myself I don’t use pesticides and instead rely on worm castings to protect the plants from pests and diseases. I have a Eugenia hedge that was here before I came to this property and, unfortunately, it can develop a blight and disease. My gardeners spray them only with a strong spray of water from the hose and they also sprinkle the worm castings on top of the ground at the base of the plants.

Zinnias love worm castings.

With the consistent use of worm castings all our gardens can become healthy mini ecosystems that give peace of mind.
Don't you find the garden inspirational? Fine artist Francesca Filanc sure does! Acrylic on canvas, 60“ x 40“, ‘South Beach’ by Francesca Filanc.

Enjoy the many benefits of gardening with worm castings and watch your trees, plants and shrubs thrive along with birds, butterflies, dragonflies, frogs and even an occasional coyote meandering through the garden.

Happy gardening!

- Francesca


Artist, author, photographer, fly-fisher woman, Francesca Filanc grew up in old Del Mar and these days lives, paints and gardens in historic Olivenhain with two French poodles.

Find her art and writings here:


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