What Are Worm Castings and How Do You Use Them in the Garden?

Plants need the macronutrients and micronutrients that come from the decomposition of organic matter to thrive, and earthworms help speed up the compost process. The product they release is called worm castings, or vermicompost, and it’s what’s left behind as earthworms eat their way through old leaves, food scraps, and other materials that are found in a compost pile.

Want to add worm castings to your garden? Here’s more about worm castings, their benefits, and how to produce and harvest them at home.

What Are Worm Castings?

At their most basic level, worm castings are worm droppings. Worms will make their way through the soil, eating nearly everything in their path. This includes yard waste, food scraps, decaying leaves, and other organic matter—anything that can decompose is on the menu.

Worm castings are the result of the earthworms digesting all of the organic material found within the soil or a compost bin and turning it into a nutrient-packed matter that plants can use to power their growth. The decomposition process of organic matter can take up to 18 months on its own, while the process of earthworms creating worm castings takes only six to eight weeks.

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Benefits of Worm Castings for Plants

Think of worm castings as a natural fertilizer that will help your plants thrive and grow to their fullest potential. They improve the soil texture and add easy-to-utilize nutrients into the soil, giving plants a boost. Here are a few of the specific benefits that you can expect when worms get to work.

• Richer soil: Thanks to the worm castings, your soil will be packed with nutrients and microbes that plants need, including nitrogen, phosphorus, potassium, magnesium, sulfur, calcium, chlorine, iron, and zinc.
• Improved soil texture and moisture: Soil that’s rich in worm castings is more aerated, making it easier for roots to move throughout the soil and allowing the soil to both drain and retain moisture.
• Fewer diseases: An enzyme called chitinase is produced in the worm casting process, and it helps ward off plant diseases.
• Faster growth: Fertilizer encourages faster growth, and worm castings can be even better than a fertilizer. You can expect seeds to grow faster and plants to produce fruit and flowers quicker, too.
• Stronger roots: Because the roots are easily able to take hold in a worm casting-rich soil, they’ll grow stronger than if they were working an uphill battle against a non-enriched soil.
• More pollination: Healthier plants mean more flowers, which means more pollen for pollinators.
• Sustainability: Rather than purchasing manmade fertilizer, you’re leveraging the earth’s natural processes to feed your plants.

How to Use Worm Castings in the Garden

You can use worm castings on any plant, at any stage.

Add Worm Castings to Seed Trays and Seedlings

Add them to seed trays when you start the season’s crops or use them to help boost growth in seedlings. The rich nutrients will help young plants get their footing, and the texture or worm castings will help the roots take hold in early stages.

Give Transplants a Helping Hand

Worm castings can help ease the transition of transplants. Add a few teaspoons of worm castings to provide nutrients that will help the transplants get their footing and start bursting with new growth.

Sustain Health and Growth in Mature Plants

Even older plants need a boost from fertilizer on occasion. Add one to two cups of worm castings to the top layer of mature plants’ soil seasonally. This help maintain the nutrient levels within the soil and keep the plants happy and healthy.

Plants That Benefit From Worm Castings

Some of the plants that benefit most from worm castings including vegetables, herbs, flowers, and indoor plants. They can be used on young plants and old plants alike, and worm castings will not burn or harm any plant.

How to Make Your Own Worm Castings

To make your own worm castings, start with a bin, bucket, or designated compost pile. Create a bed on the bottom with a mixture of moist newspaper or cardboard, sand, or peat moss. Add layers of compost, including decaying yard waste or leaves, food scraps, or other organic matter. Add worms, and let them get to work chomping through the feast of organic material.

How to Harvest Worm Castings

When your compost bin or bucket has little of the original food, yard waste, or organic matter remaining, it’s ready to harvest. You should have a dark brown, finely textured material that resembles an even soil. Dump the bucket or bin out on a flat surface, then use the top of the soil, ideally without the worms in it—you want them to go back into the bucket where they can do their work on the next round.

Disadvantages and When Not to Use Worm Castings

While worm castings won’t hurt plants, they’re not right for every garden. Here are a few of the reasons you wouldn’t want to use worm castings in your garden.

• Large garden space: Unless you have a giant kitchen to fuel your compost pile, you probably won’t create enough worm castings to feed a large garden.
• It takes time to make: While worm castings are faster than waiting for natural decomposition In the soil, they still take six to eight weeks to harvest.
• Expensive to purchase: You can buy worm castings, but they’re more expensive than a standard fertilizer.
• Can develop mold: Because they’re made of organic material, worm castings can develop mold if they stay moist for too long.