Worm Castings: The Complete Guide [Updated 2020]

Worm Casting are the “One Stop Shop” fertilizer for any garden or yard. It’s ALL you need for the most productive garden and most beautiful flowers. PERIOD

Let’s talk about What Are Worm Castings?

Worm Castings are simply the waste product from earth worms. Worms eat dead plant matter and digest it. Bacteria in the worm’s digestive track break down the plant matter into its most basic form. The material that doesn’t get absorbed by the worm’s digestive system is high in concentrated nitrates, phosphorus, magnesium, potassium and calcium and is excreted as castings or waste. It also contains manganese, copper, zinc, cobalt, borax, iron, carbon and nitrogen.and serves as fertilizer [food] for plants.

There are also enzymes/microbes in the waste that make it even more nutritious and easily absorbed by plants. The worm’s enzymes and microbes are responsible for breaking down the worm’s food into very basic compounds.

Think of worm castings as Baby Food…very nutritious and easily digestible.

Worm Castings: What it does

Worm castings are simply the absolute best fertilizer for gardens, grass, flowers, trees and shrubs. The reason it is the best fertilizer is that it’s already broken down to a level that is easy for plants to absorb. Other fertilizers need to be broken down before plants can absorb it, even compost.

Worm castings are 100% natural and can never harm any plant no matter how little or how much you apply to the soil. It’s the “Fail Safe” fertilizer.

Worm Castings will enrich any soil [even sand] and enable plants to grow faster, healthier and produce more fruit. You can see the difference in days. It’s remarkable.

Benefits of Worm Castings

  • All-In-One fertilizer
  • 100% safe
  • Organic
  • Promote rapid growth
  • Promotes growth of more and bigger fruit
  • Prevents diseases
  • Enhances any soil

How to Use Worm Castings

You can just apply worm casting on top of the soil in your garden, around trees, shrubs, grass, etc. Always apply it to the drip or root line and not directly against the trunk or bulb. Apply it where the roots are. The nutrients will seep into the soil whenever it gets watered. You can apply as much as you feel like. Typical applications are about 1-2 inches of castings on top of the soil.

Optimal Method: First aerate or loosen the soil in the area you would like to fertilize like the garden or around trees. Mix/till the soil with as much castings as you like. When the soil is aerated or tilled, it’s easier for the nutrients in worm castings to penetrate the soil when watered. Plant roots will be able to absorb the fertilizer faster and easier when using this fertilizing method. Mixing the soil with castings will also preserve moisture, prevent compaction and promote aeration.

Now apply a layer of worm castings to the top of the loosened soil. I usually add about 1 inch of worm castings to my garden and around my trees. This will provide nutrients for about 3-4 months. I usually apply more every 6 months to keep plants healthy and growing.

Worm Castings Tea

Worm casting tea is a liquid fertilizer made from worm castings and water. It’s used to fertilize plants and protect them from disease. You can water plants like normal with it and/or spray over the entire plant, leaves and all to protect it from disease.

How to Make Worm Castings Tea

What you need

  • 4 cups Worm Castings
  • 1-2 gallons of water [un-chlorinated if possible, like rainwater]
  • 1 oz Molasses or sugar [food for beneficial microorganisms or microbes]
  • Aerator – like an air stone and air pump for aquariums
  • 5 gallon Bucket

Mix the worm castings, molasses and water in the 5 gal bucket. Setup aeration in the bottom of the bucket so it circulates the water. Now let it aerate for 3 days.

Now use the worm castings tea to water your plants and watch them grow.

How to Store Worm Castings

The cardinal rule of storing worm castings is…don’t let it get moldy from too much moisture. Keep it dry in a container with a lid or in a plastic or burlap bag . Store it in a dry location.

Popular Brands of Worm Castings

Wiggly Worm
Worm Gold
Brut Worm Farms
Bloom City – worm castings tea
Life Cycle Organics
Sun Gro Black Gold
Wonder Soil

Where to Buy Worm Castings

You can usually buy worm castings locally. Worm farmers will sell castings and worms. I found a local worm farmer [The Arizona Worm Farm] in Phoenix, AZ. The worms and castings are pretty cheap. You can also find online stores that sell worm castings in bags. Here is a link where you can buy worm castings…Buy at Amazon.com.

worm castings 5 lb bag

How To Make Your Own Worm Castings

It’s actually pretty simple. Basically, you get a plastic container and put worm bedding, food and worms in it and wait 3 – 6 months.

Here is a List of Items Needed

  • Plastic storage container/bin with lid
  • Worm Bedding – compost, coconut coir, paper, cardboard, straw, yard dirt, etc.
  • Worm Food – kitchen scraps like lettuce, egg shells, fruit, banana peels, carrots, etc
  • Red Worms – these are special composting worms that eat a lot and reproduce quickly. They are not the typical worm you find in your yard.

It really is that simple.

Here’s how you setup a Worm Farm

Plastic Storage Container/Bin
Buy a dark colored storage container/bin with a good fitting lid. Do not get a clear container. Worms like it dark. You can get one as large as you like.

Regarding the dimensions, look for something with more surface area. You ideally do not want something square and really tall. Look for a rectangular bin that is longer than it is tall. Here is a good one’s dimensions, 14 gallon storage bin – 24.5″ L x 16.75″ W x 10.5″ H. I just bought one at Walmart for $9.99.

worm farm plastic bin

This design just makes it easier to manage and gives the worms more area to crawl around. It also lets more oxygen get into the soil.

Prepare the Worm Farm Bin for Aeration
Drill 1/4″ ventilation holes in all sides of the bin. Start about 2″ from the top and space the holes about 1″ – 2″ from center to center. Drill the holes in a 4″ – 5″ band all the way around the bin. This will allow good air circulation. Now the worm farm bin is ready.

I read several articles on making a worm farm bin and some suggested drilling holes in the bottom for drainage. I don’t agree with this but that’s just my opinion. If you need drainage for excess water then you are adding too much water. If you happen to do this just add more dry bedding to absorb the water. I prefer a sold bottom to retain moisture and keep the worms from escaping.

Worm Bedding
Worm bedding can be a lot of things and should be a good mixture of a lot of things.

Here is a list of bedding materials

  • Coconut Coir
  • Unbleached paper without colored ink
  • Cardboard
  • Compost
  • Newspaper
  • Egg crates
  • Straw
  • Soil
  • Egg shells

Worm bedding is where the red worms will basically live. They will also eat this material eventually and turn it into worm castings.

The bulk of worm bedding should be Coconut Coir or Compost. Then mix in some paper, cardboard, backyard dirt for grit and egg shells for minerals. Now moisten the mixture so that it feels like a damp sponge. You don’t want it soaking wet…just DAMP. If you grab a handful and squeeze it, only a few drops of water should drip from it.

Now add some worms and table scraps and then cover them with the bedding. Worms don’t like to be above the surface. Now put the worm farm bin lid on and keep in a shaded spot outside to keep it a little cooler.

What to Feed Your Worms

  • Vegetables
  • Fruit
  • Grass
  • Leaves

What NOT to Feed Your Worms

  • Dairy
  • Meat
  • Spicey fruit like hot peppers, chili’s, Serrano’s, ghost peppers, etc
  • Citrus
  • Animal fat
  • Oil or grease
  • Bread or sugar

Keep the worm bedding moist by adding a little water when it gets dry. Try to use water that has been sitting 24 hours instead of tap water. It’s better to use water without chlorine.

If you accidentally add too much water, just add more bedding to absorb the excess water.

Add table scraps [worm food] when you see none left from the last time you added it. Try not to add too much at one time because it will rot and smell. It’s better to add not enough than too much. Monitor how much your worms eat in a week and adjust how much you give them. It’s also a good idea to put the food in a different place each time. It gets the worms moving around more. A good thing!

When most of the worm bedding has been turned into castings, it’s time to harvest the castings. Or it can be whenever you want.

So how do you separate the worms from the castings?

It’s actually quite easy…Push all of the castings and worms to one side of the bin. Now add fresh bedding and food to the other side. Wait 1 – 2 weeks. All of the worms will move to the side with fresh bedding and food. Now the castings will be empty of worms and you can scoop it out.

Can You Use Worms from Your Yard?

I’ve had several readers ask if they can harvest worms from their backyard to start a composting worm farm.

The answer is Yes. I’m actually going to try this. I don’t know how it will turn out though. I read that red wigglers are the best because they eat a lot and reproduce rapidly. I don’t know what species of worms I’m attracting in my garden but they are smaller like red wigglers. There’s only one way to find out.

I’m attracting worms in my garden right now. I loosened the soil and mixed it with some compost I bought from Lowes. I also have a good 1″ layer of compost on the top of the soil. I have been burying veggie scraps in the garden periodically. Then I water everyday to keep it moist. I’ll continue with this for about 2 weeks.

When I dug a hole to bury some scraps on Sunday [9/20/20], I noticed some worms in the soil already. Yippee! It’s working…even in Arizona’s hot desert climate.

I’m attracting worms in September with a high temperature of 105 degrees.