The Science Behind Bone Meal

By Kathryn Van Druff
Published: May 11, 2020 | Last updated: April 23, 2021 01:23:58
Key Takeaways

Bone meal is a common garden supplement, but what is it, why is it so widely used, and what plants benefit the most from it? All of these questions can be answered when you understand the science behind bone meal.

It’s no secret the harvests we reap are a direct result of the crops we sow and how we care for them. All things considered, watering, weeding, pest control, and soil quality all factor into the flowers, plants, fruits, vegetables, and herbs we can expect to enjoy during the growing and harvesting seasons. Using bone meal for plants is not a new technique, but it can improve the outcome of your plantings when introduced properly. Natural bone meal fertilizer can correct a deficiency in phosphorus or calcium in your garden soil, yet that is just one of its many helpful properties. Here’s the scoop on what bone meal is, how and why it works, and how you can use it in your garden.


What Exactly Is Bone Meal?

Bone meal fertilizer consists of defatted ground animal bones and byproducts repurposed from slaughterhouses. The finely and coarsely ground bone fragments act as a slow-release fertilizer delivering phosphorus and protein to plants, flowers, shrubs, and trees.

As a natural fertilizer, the nitrogen-phosphorus-potassium (N-P-K) ratio for bone meal is not always consistent. Sometimes the range may be on the low side, such as 3-15-0, while other times it can be as high as 2-22-0, or somewhere in between.


The nitrogen concentration itself isn’t truly high enough to provide all the plants need, but bone meal is a certainly good source of phosphorus and calcium.

The Scientific Breakdown of Bone Meal

Akin to its namesake, bone meal fertilizer begins as discarded bones, usually derived from animal slaughterhouses in the meat industry. To make the bone meal, meat bone waste products are steamed and ground down into powder or tiny particles for use in the garden. In addition to phosphorus, calcium, and minimal nitrogen, bone meal may contain minerals such as zinc, magnesium, and iron, among other trace elements.

Read also: What’s N-P-K Anyway?


Following application, mycorrhiza fungi microbes in the soil help to digest the bone meal, which then integrates with existing organic matter and fortifies the soil with plant food, ready for root uptake. The plants give their thanks by giving the mycorrhizae sugars and amino acids in return. The increased phosphorus and amalgamation of organic components can result in stronger and more prolific roots, better ability to winter over, and quicker plant growth to maturity. Production can also increase as plants absorb more nutrients during the slow release of the bone meal’s key ingredients.

Benefits of Bone Meal

Bone meal fertilizer is widely accessible and easy to apply no matter if you’re a seasoned farmer or an amateur home gardener. The benefits of using bone meal in the garden can leave a lasting impression with precise application and care.

Bone meal is easy to apply. This fertilizer is a cinch to use, even for novice gardeners. For best results, add it to the soil before planting, preferably at the bottom of the planting hole, or even atop your compost pile. You can also mix it into the soil surrounding existing plants and watering over top once per season if needed.


Bone meal can provide phosphorus to depleted soil. As long as the pH of the soil is below 7, the phosphorus levels can improve with addition of bone meal. If the pH is 7 or above, the roots cannot absorb the phosphorus from the soil.

Soil becomes more fertile with bone meal. Amending soil with bone meal encourages growth, flowering, and better production.

Bone meal creates balance. When added to soil along with fertilizer with high nitrogen content, bone meal can help produce the right blend of nutrients in the soil.

Organic farms and gardens can use bone meal. Organic bone meal abides by the requirements of organic farming. This natural fertilizer can help plants and crops within the guidelines of organic agriculture.

Read also: How to Overwinter Your Pepper Plants

Special Bone Meal Considerations

As with any good thing, bone meal comes with its own precautions as well. Here are five special considerations to keep in mind about using bone meal fertilizer.

Check the soil’s pH first. The pH must be below 7 for the plants’ roots to be able to absorb the bone meal. Should you find the pH is too high, work on amending the soil’s pH before you go ahead applying any bone meal.

Mix, mix, mix! It’s important to remember to mix the fertilizer thoroughly into the soil for safety as well as best results. While generally regarded as safe, the formula can cause negative reactions — in particular, gastrointestinal problems — if taken internally.

Monitor usage. Although bone meal is relatively forgiving, it’s important to monitor how much you’re using. Adding too much bone meal won’t scorch your plants in the way that blood meal can with burned leaves and other damages. Bone meal does, however, run the risk of chlorosis, a loss of the green pigment in leaves that occurs as a result of reduced chlorophyll production. One application during the growing season will likely do the trick for your needs.

Don’t forget the butterfly effect. Note you may wish to avoid powder-based, water-soluble bone meal formulas if you have ponds, fountains, or other areas where runoff would be problematic. The phosphorus in the fertilizer could lead to overgrowth of algae blooms that could rapidly affect the balance of the ecosystem.

Wear a dust mask. Although it’s unlikely you would come across contaminated product for your own gardening needs, you can search for bovine-free blood meal if you prefer. Wearing a dust mask when working with bone meal is an easy and inexpensive extra step with merit for peace of mind.

Interestingly, bone meal used to be dietary supplement for livestock, particularly for cows; however, the advent of bovine spongiform encephalopathy (BSE), more widely known as mad cow disease, required immediate cessation of those practices. Studies found traces of infected spinal cord, brain matter, and other nervous system components could survive production processes into the packaged bone meal, which cows ate and then became infected. The risk of contracting the human variant, Creutzfeldt-Jakob disease (CJD), centers on consuming tainted meat, although inhaling contaminated bone meal dust particles may also transmit the disease, according to some studies.

Thanks to the widespread awareness and updates to farming and meat processing operations, incidence of disease is significantly low. While the epidemic largely took place in the United Kingdom, routine testing practices worldwide aim to prevent another outbreak.

Adding Bone Meal to Soil

Bone meal can make a noticeable difference in the quality and condition of your plants. Consider adding bone meal to soil for a better growing experience. Follow these steps to incorporate bone meal into your gardens.

Read also: How to Test the pH Level of Your Soil

TIP: Before you begin adding bone meal to soil, first test the soil’s quality, including the pH level. If the soil pH is 7 or greater, you must first tackle the issue of the high acidity of your soil. Phosphorus uptake occurs only when the pH level is below 7 in a more acidic state.

How to Add Bone Meal to Your Garden

For New Plantings: Dig a hole the appropriate size for your plant and sprinkle a few tablespoons of bone meal into the bottom of the hole and complete your planting accordingly.

For Existing Plants: Gently sprinkle and mix a few tablespoons of bone meal into the soil surrounding your plant and mix it in with a hand trowel. Water appropriately for the type of plant.

For Compost: Sprinkle a bit of bone meal into your compost heap to add nitrogen and heat up the pile.

When in doubt, follow the instructions on the bone meal packaging. Using bone meal for plants can inspire remarkable improvements in your garden, from more vigorous root growth to more prolific blossoms and fruit or vegetables.

What Plants Like Bone Meal

Provided the soil’s pH is suitable for phosphorus uptake, many different plants can benefit from bone meal application. Flowers, fruit and vegetable plants, decorative plants, and even trees can benefit from bone meal. For best results, test your soil to get a baseline view of the nutrients and minerals and then amend the soil to the ideal levels for what you’re growing.

Bone Meal for Flowers — Use bone meal fertilizer for flowers like roses, hydrangeas, tulips, and lilies. Giving bulbs a burst of phosphorus in the fall can help to increase root growth for a better spring blooming season. Adding bone meal for bulbs can also encourage more plentiful and showier blooms. For best results, add the bone meal directly to the planting hole or incorporate it as close to the roots as possible.

Bone Meal for Fruit and Vegetables — Tomatoes, peppers, potatoes, onions, and other bulb-like or root vegetables can all benefit from the extra phosphorus in bone meal. Fruit trees could benefit from added phosphorus if the soil is not already replete with nutrients. Remember sandy soils will call for more phosphorous.

Remember to test your soil prior to applying any additives. Check the requirements for the plants you’re growing and work to find the right balance in your soil composition. Also, bear in mind you’ll only need to do one application per growing season as bone meal takes about four months to move through your garden and into the plants.


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Written by Kathryn Van Druff | Freelance Writer & Marketing Specialist

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Kathryn M. Van Druff is a freelance writer and marketing specialist with her own business, Dances with Words. She has years of experience writing about gardening, landscaping, and home design topics. Kate is also an avid home gardener, wife, and mother to two daughters and a border collie.

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