Worm castings explained: Natures best fertilizer for healthy plants

When soil becomes hard and it does not absorb water, it means that there is no air remaining in the soil. It indicates that the aerobic microbes present in the soil which help in nutrient cycling, are dead due to lack of air. These microorganisms play a role in fixing nutrients that are essential for plants. They die due to repeated use of chemical fertilizers and fungicides. As a result, plant leaves turn yellow and growth becomes slow. 

When using natural fertilizers like worm castings, it helps retain water in the soil and keeps it moist. These fungi and other beneficial bacteria absorb moisture, swell up, and create space between the soil particles by pushing them apart. So,  when soil quality improves, it boosts plant growth. Vermicompost is a natural growth hormone for plants and soil which provides nutrients and loosen compacted soil, and make it fertile again.

What Are Worm Castings?

Worm Casting, which means excreta (faeces) of worms, is a powerful and nutrient rich fertilizer. When earthworms, like wigglers (Eisenia fetida), consume organic materials like food waste and leaves, after passing through their digestive tract it converts into healthy and nutrient rich manure. This process is called Vermicomposting.

Nutrients which are present in worm casting are water soluble, which plants can absorb easily. Vermicompost for vegetables works as a natural soil amendment and conditioner which is used to improve the soil quality and boost germination. It contains nitrogen fixing bacteria like: 

Azotobacter converts nitrogen to NH3, which helps plants to utilize ammonia:

• Agrobacterium which increases the microbial diversity and 
• Rhizobium increases nitrogen availability, solubilizes phosphate and produces phytohormones.

Worms' digestive system creates the living environment for the soil, which supports microbial activity. It improves the texture of soil so the plants can get better nutrients. Worm casting makes soil loose and aerated so that roots of plants can get oxygen to grow in a better way.

Nutritional and Biological Composition

Worm casting is not only fertilizer, it is a complete nutritional package for plants and soil. Here is a little brief of nutritional and biological composition of worm casting.

Macronutrients

Earthworm casting is enriched in nutrition. They naturally contain Nitrogen, Phosphorus and Potassium and they are known as macronutrients. Research shows that worm casting typically NPK ratio is to 5-5-3.

• Nitrogen(N): It is present naturally in high concentration which is beneficial to grow vegetative parts of the plant like roots, stems, and leaves. Nitrogen produces chlorophyll which is important for the greenness of the plants.
• Phosphorus(P): Phosphorus is present in earthworm casting in enriched levels that means phosphorus is present naturally, but in some cases, the ratio increases depending on the worm's diet. It is important to stimulate the growth of flowering and fruiting.
• Potassium(K): Worm casting contains abundant presence of potassium; it means there is no need to concentrate or add artificially. It is important for overall health, enhances the fruit quality and prevents disease.

Micronutrients

Micronutrients are needed in small quantities, but they are very important for plants. Worm casting provides Calcium, Magnesium, Iron, Sulphur, Zinc, and Copper in natural, balanced, and easily absorbable form.

• Calcium: Present in moderate level in casting which provides the beneficial impact by activating some important protein and enzymes which help to influence the structure of cell walls.
• Magnesium: Magnesium present in traceable amounts in worm casting which is important to support in the formation of chlorophyll.
• Iron: Iron present in the casting helps in the process of photosynthesis to convert the light energy into chemical energy. In plants, iron is also a part of energy production, it helps to transfer the electron.

Microbes

Aerobic microbes play a crucial role in worm casting to provide benefits to both plants and soil. They are microorganisms which can work in the presence of oxygen and convert the soil into “living soil”. Nitrogen fixing bacteria, take nitrogen from the air and convert in absorbable form for plants. 

Moreover, phosphate solubilizing bacteria which dissolve the phosphorus present in soil and send it to roots. In worm casting, actinomycetes and some beneficial fungi (like Mycorrhizae) are also present which make soil loosen, fertile, and fungus free. These microbes increase the water holding capacity of soil and improve the nutrient cycle to make plants strong and healthy.

Benefits of Worm Castings for Plants and Soil

Worm castings fertilizer benefits are not limited to improving soil only but also it is beneficial to protect the environment. These organic materials pass through the digestive duct of the earthworms which act as the source of slow release nutrients. Humic and fulvic acids eliminate the toxins and harmful fungi from the soil. As a result, the risk of contamination is decreased.

Worm casting pH level ranges from 6 to 7.5. This range helps to balance the pH of soil and makes possible the growth of plants where acidity and alkalinity is high. Additionally, worm casting also increases the resistance to pest attacks like aphids. 

Soil which is treated by worm casting increases the chances of bee pollination. The nectar of those healthy flowers attracts the bees to stay longer and visit these abundant plants again for pollination.

According to the test results, performed by Cornell University, UC Davis and the Australian SIRO shows that worm casting improved the yield from 15% to 57% and also improvement in taste, appearance, and flower’s size, color and blooming quantity.

How to Use Worm Castings

The correct usage of casting can make a garden more productive. There are some ways given below to understand how to use worm castings in garden:

Small Planters and Pots

• Take one portion of worm casting and mix it with 3 portions of soil.
• Top dress every plant after 2 weeks with ¼ cup of worm casting.
• Repeat this process for 3-4 months.
• Add approximately 25 worms per planter to aerate soil.

Root Crops

• Insert the worm casting 1” to 2’ in the hole where seed furrows.
• After 4-6 weeks ⅛’ side dress of casting.
• To get ready soil, mix 3-4 pounds of casting in every 100 sq.ft.

Tomatoes, Chillies, Brinjal, Beans, Cucumber, Melon

• One part of worm casting mix with 4 parts of soil.
• Insert this mix in the hole first then place the plant and cover it.
• After budding, every plant covers the top with ¼ cup of worm casting.
• Add 30% of the casting with peat/humus to create a potting mix.

Roses, Shrubs, and Trees

• Cover with mulch after adding 4 cups of casting mix on the surface of every plant.
• For a new plantation, take a 1:2 ratio of casting and mix it with organic peat or compost and insert it before planting.
• For old shrubs use 4 cups of earthworm casting with mulch.

Herb Garden

• Either grow seed or transplant it and give ½ oz. of casting to every plant.
• Recasting in mid season.
• Mix 5-10% casting with peat or humus for better results.

Fruits and Nuts Trees

• For every 1” diameter of tree cover the top with 2 cups of casting from trunk to drip line.
• When transplanting use a 50/50 ratio of casting and compost mix.
• In spring and autumn season apply 5-7 lbs amount of casting.
• For established trees give 2 to 3 times in every year, 5 lb casting per inch.

New Lawns (seed and sod)

• Put 10 lbs of casting of every 100 sq. ft.
• Add casting into the seed bed before inserting seeds, and give water to them.
• For sod, put ⅛” of casting on the surface and water adequately.
• To maintain use, 5 lbs casting per 100 sq. ft.

Top 5 Worm Casting Products

When comparing the worm castings vs compost, worm casting provides more concentrated nutrients and beneficial microbes. Here are the top 5 products of worm castings available at Growcycle.

1. Gaia Green Worm Castings

Gaia Green Worm Castings is one of the best quality vermicompost which is prepared from the African night-crawlers. These worms are fed peat moss and organic grains; this is the reason they are full of nutrients and beneficial microorganisms.

Due to its high content of organic matter, it increases the soil's nutrient-holding and water-holding capacity. This product also improves the structure of the soil so that better aeration and drainage is achieved.

• Recommended to use 5-10% of this product during transplanting.
• Guidelines of this product are also given to use it safely.
• Use every month for household plants.

2. Greengro Premium Worm Castings

GreenGro Premium Worm Castings, commonly known as Pride Lands, is a high quality and gentle organic plant food to enrich the soil. These castings not only provide essential nutrients, but also improve the balance of fungi, bacteria and other organic matter.

Greengo casting is beneficial in every stage of plant growth whether it is the seed stage or maintenance of mature plants. 

• It can easily dissolve in cold water to make solution.
• This worm casting is also used as foliar spray.
• It helps to revive depleted or exhausted soil.

3. True Organic Worm Castings

True Organic Worm Castings is a 100% organic and eco-friendly fertilizer which is specially designed as vermicompost for vegetables, fruits, flowers, and foliage. This fertilizer's primary advantage is that it enhances microbial activity in the soil, thereby boosting plant growth and yield.

It contains a total of 1% nitrogen, of which 0.95% is in the form of slow release, allowing plants to get nutrients for long periods of time. However, its clean and natural soil amendment makes it safe for the environment and plants.

• No risk of over fertilization due to slow release mechanism.
• Its smell-free nature makes it best for indoor gardening.
• It makes soil porous and well-aerated.

4. Earth Science Earth Worm Castings

Earth Science Earthworm Castings is a pure and premium quality vermicompost organic plant food. This casting is made without any filler and prepared using organic matter. It ensures that soil microorganisms get fed and land becomes more productive. This Earth Science product is used not only for plant nutrition but also as a natural deterrent for small pests and critters.

Additionally, earthworm casting can be applied directly in soil or compost piles. It is also used to make liquid plant food. Earth Science made this product with 25 years of commitment, where they promote nature-friendly gardening.

• It is in the form of granules.
• It is suitable for every type of plant either in a container or in the ground.
• Application is easy and mess free.

5. Wiggle Worm Pure Worm Castings

Wiggle Worm Pure Worm Castings is high quality organic fertilizer  based on 100% worm castings. No leftover worm bedding or vermicompost is mixed in the casting. It is prepared with a unique harvesting process, that's why it is officially recognized as a fertilizer.

Wiggle worm castings consist of small football shaped particles which improve the capability of soil aeration and water retention in plant roots. This product is odor free and non toxic, making it best for both indoor and outdoor environments. 

• It can be used on vegetables, flowers, and household plants.
• This worm casting is easy to use due to its granulated form.
• Weight of this product is 30 pounds per bag.

When to Add Worm Castings to Garden Soil

Time is an important factor to add casting in the soil because the right time increases the benefits of earthworm casting. Below are some stages for using worm manure:

1. At the Time of Planting or Transplanting: When planting new plants insert the worm casting into a newly dug hole so that roots get direct nutrients. To reduce the transplant shock and promote growth use 1 part of worm casting mix it with soil for beneficial results.
2. During the Growing Season (Every 2–3 Months): Top dressing the soil after 60 days to maintain the nutritional balance. Casting releases the nutrients in a natural way which produce resistance against plant diseases. Add worm casting after rain so that soil absorbs all the nutrients.
3. At Flowering or Fruiting Stage: Worm casting contains enzymes and hormones which naturally boost flowering and fruiting. When plants at flowering stage use worm casting which provides good color to flowers. In fruit plants it improves the shelf life and taste of the fruits.
4. In Early Spring (Before Planting): At the start of spring, adding worm casting in the soi it activates the beneficial microbes promptly. Improve the germination rate of seeds and make seedlings healthy. Worm casting decreases the compactness of the soil which is important for root development.
5. In Fall (Post-Harvest Soil Amendment): Add worm casting to maintain the fertility of soil in the winter season. Due to worm casting the ecosystem of the beneficial organisms which make the soil alive. Insert the casting under the mulch to fast the process of composting.

The Bottom Line

Worm casting is not only an organic fertilizer but also a smart investment to increase productivity and health of the garden in the long run. Ideal for people who want to make their land better in a sustainable way without using chemical fertilizers. Growcycle’s trusted, high quality worm casting products provide chemical free and healthy growth of soil and plants. It is a smart choice for a gardener of all levels. 

Disclaimer: This material is for informational purposes only and should not be relied on for legal, medical, financial, or any other form of professional advice.

About the Author

Victor Miller

Environmental Journalist Focused on Sustainable Agriculture

Victor Miller is an environmental journalist at Growcycle, specializing in sustainable agriculture. With a passion for storytelling, he highlights the latest trends, innovations, and practices that promote ecological balance and responsible farming.