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Who will come out on top in the battle of worm castings vs. bone meal fertilizers? This article looks into the features, benefits, and disadvantages. We also explain why we think organic worm castings are better to use on your plants and improve your soil's health. 

Our Pick: Worm Castings

Worm castings (like Simple Grow) are among the best overall organic fertilizers for your plants. This fantastic natural soil conditioner is worm poop, the waste by-products of earthworms, one of the most important insects in the soil microcosm. 


  • Natural pest repellent. Harmful insects that attack your plants, such as aphids, mites, and mealybugs, do not like worm castings and move away from the area.
  • Worm castings supply the soil with healthy bacteria and extract harmful fungi, bacteria, and toxins.
  • It provides living organic matter to the soil, supplementing its nutrients and microorganisms.
  • Also known as vermicast, these droppings are an excellent pH neutralizer. They help reduce acidity in acidic soils and increase acidity in alkaline soils. 
  • Improves soil aeration. Worm castings look like footballs, creating tiny air pockets in the soil.
  • Their shape also helps reduce soil compaction and aids the formation of soil clumps, known as soil aggregates. Aggregates reduce erosion and hold pockets of air in the soil.
  • Nutrients are released slowly into the soil, providing the plants with the elements they need on a demand basis.
  • The worms feed on organic matter, which means their soil castings are chemical and additive-free. 
  • Worm castings have a higher percentage of nitrogen than regular soil, and its slow release helps stabilize the nitrogen levels when growing tomatoes, for example. 


  • It does not cause fertilizer burn
  • Suitable for indoor and outdoor gardening
  • No need for a patch test on the soil
  • Improves overall soil health


  • Plants sometimes need it in conjunction with other fertilizers to get the macronutrients they need

Bone Meal

Bone meal is an extremely popular fertilizer made up of steamed animal bones and then ground to a powder. Full of minerals and nutrients that nourish the soil, it is easily absorbed by the roots and helps with soil amendment.


  • This fertilizer is rich in phosphorus, an essential component of any fertilizer, as the mineral is crucial in the plant's photosynthesis, flower, and seed production. 
  • An annual application is sufficient. Bone meal is an excellent slow-release source, so you can apply it once a year and forget about it.
  • You can buy it in powder or meal form. Sourced from cows, the bones are steamed and ground for better plant absorption. 
  • Bone meal also has high levels of nitrogen and potassium, which is another vital component of all fertilizers. Plants need nitrogen during photosynthesis, and it is also the main component of amino acids, which are the building blocks of protein. 


  • Slow-release fertilizer
  • High source of nitrogen and phosphorus
  • Organic
  • It helps boost the growth of plants to produce more crops and greener grass


  • Bone meal can attract predators such as dogs that dig up your garden soil
  • Ingesting it might also be toxic for the animals
  • Bone meal is not suited for all soil types. If the pH of your soil tends to be alkaline, then the bone meal will not have any effect

Similarities Between Worm Castings and Bone Meal

You can easily confuse worm castings and bone meal. 

Both fertilizers are slow-release sources of nutrients for the soil and plants, so if you are looking for a fast-acting fertilizer, you need to think long-term when planning your garden and crops.

Bone meal and worm castings have high levels of phosphorus and nitrogen, which help boost plant growth and are rich in trace minerals. Both are good sources of calcium and potassium. They are also organic, additive, and chemical-free, vital for your plants and soil health. 

Differences Between Worm Castings and Bone Meal

Although organic fertilizers, bone meal, and worm poop bring different elements to your plants and, eventually, the table. Here are the main differences between the two products. 

Plants thrive in soil rich in worm poop. Worm castings do more than provide nutrients to your plant. They improve the soils' health, water retention rate, create aeration, and prevent root diseases. Castings also contain humic acids, which stimulate plant growth and good microbes in the soil. They are also highly water-soluble. 

More importantly, worm castings are not toxic to the soil's health and conditioning, regardless of the quantity used. 

On the other hand, too much bone meal fertilizer can burn the plants' roots, preventing any absorption of nutrients. It might also lead to excessive phosphorus levels in the soil, which inhibits plant growth. 

Also, bone meal does not work on alkaline soil. Check your soil's pH before applying - if it is above seven, the bone meal will not work because the plant will not absorb the phosphorus unless you correct the pH level. 

It is also highly toxic if ingested by animals or humans, so it is essential to apply it and store it safely. 

Organic Fertilizers

You want your plants to grow, and so do we. There are a variety of organic fertilizers available - here is a brief description of the most popular.

Blood Meal

Many people confuse blood meal with bone meal fertilizer. Like bone meal, it is another by-product of the slaughterhouse, but blood meal originates from dried animal blood.

It derives from cow blood, but many products also include pig blood. Blood meal is amineral-rich, dry, inert powder and an excellent nitrogen source. 


Cow manure, or cow droppings, is probably the most popular fertilizer used by amateur and professional growers. It is low in nitrogen and full of essential nutrients to boost plant growth. Cow manure is highly water-soluble and quickly absorbed by the vegetables' roots.

Bat Guano

Bats droppings, or guano, are incredibly high in nitrogen and phosphorus and are sometimes used as a fertilizer. The droppings are shaped like pellets and are crumbly to the touch. It is an effective fertilizer but can be toxic if allowed to accumulate in residential areas. 

Similarly, you can buy seabird guano to use as fertilizer. Like the bat guano, the seabird droppings are a great way to increase soil amendment. 

Fish Bone Meal

This fertilizer consists of dried, steamed, and crushed fish bones ground to a powder. Fishbone meal has a very high percentage of phosphorus and breaks down faster than bone meal. Farmers and gardeners can use it on most crops, including tomatoes, bulbs, and compost heaps.

Compost Heaps

Creating your compost heap is an excellent way of reusing your garden waste, such as weeds, grass clippings, and leaves. Add your eggshells, tea leaves, and used coffee grounds to the mix to create a rich fertilizer for your plants.

Cottonseed Meal

Cottonseed meal transforms the by-products of the cotton plant after the harvesting of cotton and the seeds crushed. It is an excellent slow-releasing fertilizer heavy with minerals including nitrogen, phosphorus, and iron. 

Kelp Meal

Kelp meal is seaweed transformed into organic fertilizer and a source of over 70 vitamins and minerals. You can buy it as a liquid fertilizer or powder. It is an excellent bio activator, waking the microbes in the soil to help break down organic matter and increase plant absorption. Kelp is rich in nutrients and minerals such as phosphorus and calcium. 

Alfalfa Meal

Like cottonseed and soybean meals, alfalfa meal comes from fermented alfalfa seed plants. This fertilizer is one of the most popular organic fertilizers because of its easy absorption and application. It is also high in trace minerals and relatively inexpensive to purchase.


Worm castings fertilizer is the perfect all-rounder for soil, plant, and crops. The earthworms feed on organic material and produce additive and chemical-free castings. It does not burn the roots and earth, and there is no limit to how much you can apply. This type of fertilizer usesmaterialsfound in nature to boost the plant's natural growth process, and you can't go wrong with that. 

Grow Bigger Plants with Simple Grow

Do you wish your plants would grow bigger? Was your garden less than it should've been last year?

If you're tired of growing puny vegetables and fruits, it's time for an upgrade...Simple Grow Worm Castings!

What are worm castings? Another term for worm manure. Why would you want to use it in your garden, raised beds, and house plants? Because it makes them grow bigger, faster and healthier...with no chemicals!

How do worm castings do this? It's like giving your plants a powerful multivitamin with everything they need to grow. Trace minerals, nutrients, and most importantly...worm castings are chock full of beneficial microbes. Why does that make a difference?

In recent years, we've learned the importance of gut bacteria for humans and know that it impacts so many different parts of our health. The same thing applies with worms. Gut bacteria from the worm's digestive tract gets into the soil from the worm castings and promotes plant health. Plants have a symbiotic relationship with the microbes from the worm's digestive tract. Plants respond to it and grow really big...really fast!

If you've never tried worm castings before, you owe it to yourself to give them a try. Instead of using traditional chemical fertilizers from the big box store, why not try fresh, certified organic worm castings this year? You'll be able to grow bigger, healthier plants that you actually can feel good about eating. 

Take advantage of our special bundle sale on 25lb bags today!


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