what are earthworm castings

What Are Worm Castings?

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Worm castings, also known as ‘Vermicompost,’ are some of the richest, most nutrient-dense fertilizers known to gardeners. As it is becoming more and more widespread and common among gardeners, even more people who grow their own vegetables are becoming considerably interested in earthworm castings. What are worm castings? What do they look like? How are worm castings harvested? What are the benefits? These are just a few of the questions that arise.

Adding worm castings to your compost helps to aerate your soil and improve the overall structure. Worm castings provide beneficial nutrients to the soil to help your plants grow healthy and yield more fruitful harvests. Earthworm castings are also particularly helpful for those who have a problem with pests feeling on their plants, such as spider mites, and aphids. So, what do you need to know about worm castings? Keep reading to learn more about the essentials of worm castings.

What Are Worm Castings?

Worm castings are essentially a form of organic matter produced as a by-product of the earthworms’ digestive activities. Worm castings may also be referred to as vermicast or vermicompost. However you choose to say it, worm castings are basically earthworm poop. As earthworms feed on organic matter, their waste creates an enriching soil enhancement. Earthworm castings look like football-shaped particles that improve soil aeration and drainage while also increasing the water retention within the soil.

Worm castings contain an incredibly active biological mix of enzymes, bacteria, and plant and animal matter residues. The castings are full of water-soluble plant nutrients. They are packed with minerals that are imperative for plant growth. These include zinc, copper, iron, borax, cobalt, nitrogen, and carbon. For your plants to successfully absorb manure or chemical fertilizers, they need to be broken down by earthworms.

What makes worm castings so unique is how they deliver the nutrients and minerals to the surrounding plant life. As the worm digests the compost and manures, its body produces a layer of oil around the waste product. Therefore, as it is expelled, the plant nutrients are immediately available; however, they also release slowly, providing nourishment for an extended period of time.

What does worm castings look like?

Worm castings look like coarsely sandy, sifted compost. Their rich and earthy texture is similar to typical gardening compost or dried coffee grounds. They are dark brown, football-shaped particles that are slightly wet when touched. Adding castings to your soil or potting mix dramatically helps to improve the soil’s structure.

 

What are the benefits of using Earthworm Castings?

There are many different benefits to earthworm castings as they are a great source of nourishment for both your soil and your plants. Worm castings are, essentially, a plant superfood that provides many different advantages concerning your gardening efforts.

1. All-Natural, Organic Fertilizer

The best part about worm castings is that they are a natural way to optimize your garden. Earthworm castings are organic matter that is full of microorganisms that significantly improve plants’ health and yields. Not only is this organic material great for your soil, but worm castings also introduce living organic material to the soil in the form of microorganisms.

2. Odorless

Even though worm castings are bioproducts of earthworms, they do not stink like cow manure or horse manure. They do not have any smell. If you sniff it closely, it mildly smells similar to damp soil. Because the earthworm casting is odorless, they are perfect for fertilizing seedlings or indoor house plants..

3. Provides Fast-acting Growth Hormones For Plants and Seedlings

A plant’s growth is controlled mainly by a growth hormone called Auxin and a few others. The same hormone Auxin, is also found in the mucus generated in the earth worm’s body. That mucus is passed along with the bio-waste in the form of earthworm castings. When a plant or seedling is fed with earthworm castings, Auxin enters the plant’s body and acts as a growth hormone, like steroids. The plant quickly develops a lot of root mass and leaf growth. Thus, it is beneficial to apply earthworm casting to seed starting mix, new transplants, or revive a sick plant.

4. A Natural Pesticide

Did you know that using worm casting or Vermicompost around your plants can naturally protect your plant from pests like Spider Mites, White Flies, and Aphids? According to the recent studies at North Carolina State University, when earthworm castings are added to the soil, it increases the plants’ production of ‘Chitinase’ enzyme. This enzyme dissolves the outer layer (skeleton) of most insects that feed on the plant nectar. This essentially kills the insects and help control the damage to the plant.

5. Improves Soil Fertility

Worm castings significantly improve the quality of your soil. This is measure through the CEC, which stands for Cation Exchange Capacity. The Cation Exchange Capacity is a measurement of your soil’s fertility capacity. The higher the CEC, the more fertile your soil may be or could become. This provides a much better growing environment for your plants.

6. Balances Soil pH

Worm castings also have a positive effect on the soil’s ph. They act as a neutralizer and can significantly improve the acidity and state of your soil. If your soil’s pH is too high, the castings will decrease acidity within the soil. The same applies if the pH is too low. Your worm castings have a nearly natural pH, which is why they help to balance the soil to which they are added.

7. Adds Fluffiness To Soil

Worm castings are great for aerating the soil used for your plants, which significantly contributes to their granular shape. Castings are shaped somewhat like footballs, and their form helps to add more space to the soil. Creating more space creates air pockets in the soil, which is paramount for healthy soil.

8. Retains Water

The worm castings added to soil are also great for water retention. Worm castings help to absorb water by acting much like a sponge. When added to your soil, they can help increase the amount of moisture absorbed in the ground. Not only does this hydrate your plants, but it helps to protect your garden from drought.

9. Releases Nutrients Over A Long Period

Besides helping to absorb and hold water in the soil, Worm castings provide so many rich nutrients and nourishment to your plants. Even though they are readily available food source for your plants, they decompose slowly and nourish your plants on an as-needed basis.

10. Reduces Soil Erosion

In addition to providing an incredibly favorable environment for your plants, worm castings are crucial to help maintain your soil. They prevent soil erosion, reduce soil compaction, and improve the overall structure of your soil. By fortifying the structure of your soil, your plants are much better protected from flooding and degeneration.

Where Do Worm Castings Come From? How Are They Harvested?

vermicompost farming

Vermicomposting [Earthworm Cast Farming]

Typically, worm castings are grown in a greenhouse. They are kept in lowlight conditions, and the climate within the space is kept moist and warm. Boxes are filled with manure, peat moss, cotton meal, and other natural products. Then the worms are added to the boxes. As the worms eat their way through the compost of materials, they digest it all and break it down in their bodies. This is how the compost turns into worm castings. It is not unusual for worms to lay tiny eggs in the castings as well. These eggs will later hatch and become full-grown worms that continue to do the same work in your garden!

There are a few different methods used to harvest worm castings:

Dump and sort:

Harvesting Earthworm castings

One of the most popular and the most common is the dump and sort method. First, a sheet of plastic tarp or newspapers are laid out. Then the contents of the box is emptied out on the sheet.  The worms and castings will fall out onto the sheet. Individual worms are picked and added to a fresh box to continue the vermicomposting. The leftover castings from the first bin are ready to be used in the garden.

Push and add:

Harvesting earthworm casting from one bin

Another way to harvest worm castings is by moving the worms within the same bin. First, the worms and all of their castings are pushed to one side of the container. This creates about half of the bin’s size of free space on the opposite end. After enough space has been cleared, new and fresh bedding is added to the box. Fresh food (kitchen scrap) is put on the side with the new bedding. Within a couple of weeks, the worms typically migrate to the fresh food on the new side. After the worms have moved over, the castings are removed from the bin and ready to be used.

It is typical to harvest castings from a vermicomposting bin every couple of months.

One easy way to remove the worms from the casting harvest is to screen the compost. To do this, the worm bedding is sifted through a screen, and any undigested material from the finished compost is easily separated from the worms, sticks, and other materials.

Another interesting method used to harvest worm castings is through light relocation. Worms naturally move away from the light, so applying artificial light or sunlight to your castings is an easy way to separate the worms from the castings. It is essential to use caution with the method as too much light or heat can cause the worms to dry out and die. When it is time to harvest the castings, the worm tray is dumped onto a flat surface. Form mounds with the compost. Watch as the worms burrow to the middle and deep down into the compost hill. After about 20 minutes, scrape off the tops and sides of your piles.

The Bottom Line

Gardeners everywhere can benefit from the use of worm castings. If you are mainly concerned with creating a nutrient-rich environment for your plants, you will most certainly want to explore this option for your next planting season. Not only do worm castings provide an incredible atmosphere for your plants to grow in, but they also help reinforce the integrity of the soil in your garden.
Within one harvest, you are likely to see a tremendous difference in the quality of your soil, your plants, and your yields. This nutrient source for your plants is sure to change and improve your gardening efforts and practices completely.

Coming up next:

Now that you are convinced to use the worm castings for your plants, the natural question is how to use them in the garden. There are multiple ways to use worm castings at various stages of plant life. Stay tuned for the detailed article…

If you find this information helpful, don’t keep it to yourself! Share the link to this article on your Facebook page or gardening group. Your fellow gardeners will thank you for it!

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What are earthworm castings?

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7 thoughts on “What Are Worm Castings?”

  1. Hello Gopi,

    I found your article while browsing, looking for curry plant care and I am gaining a lot of knowledge/information from your articles.
    I am sure worm castings can be used for Curry plant, can I just put them on top or better to mix with bit of compost and add to the top of the soil?
    Also if I have questions can I email you directly as I hardly get a chance to come online?

    Above all please keep up the good work which helps a lot of amateur green thumbs like me 🙂

    Regards,
    Seb

  2. Could I just sprinkle some worm castings over the top of the soil of my tomato plants which are in pots? I did not mix it in with the soil when they were planted but could I just sprinkle some on top?

    1. Yes, Absolutely! After sprinkling, just scratch the top soil surface to lightly mix the worm castings with the soil.
      Good luck!
      -Gopi

    1. Hi Namita!
      Absolutely! You can use worm castings for any vegetables, flowers, fruits, shrubs and trees! You should adjust the application amount based on the size of the plant.
      -Gopi

  3. Hello Gopi,

    Thank you so much for the article. The article is beneficial to understand how we can increase the fertility of our soil.

    I do have a few questions, though:
    1. Do earthworm casting recommended for everyone? I am asking because I have only a 4×4 veggie bed. Do you recommend me to treat my bed with worm casting?
    2. If you recommend me to do so, approximately how much warm casting do I need for my 4×4 bed?
    3. Do you recommend any specific brands for the worm casting?

    Hope to get your helpful tips every day through your articles.

    Thanks.

  4. Hello Gopi,
    Is there information on seed starting Indian variety of vegetables for the zones of the US in particular zone 8 Dallas area. I am trying to research, compile put together this information in our various zones. If you already have this could you kindly share it.
    As always thank you for the great web site and information therein.
    Regards
    Srini

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