What Is Bone Meal? And What Are Its Benefits

Plants require a set of minerals for growth and development. These include nitrogen, potassium, phosphorous, calcium, magnesium, sulfur, carbon, hydrogen, oxygen, boron, chlorine, zinc, nickel, molybdenum, copper, iron, and manganese.

Bone Meal is an organic fertilizer made from ground bones. Since bones are made up of calcium, phosphorous, nitrogen, zinc, and iron, this fertilizer serves as a long-term nutritional supplement. Perfect for root vegetables, trees and shrubs.

In this post, we will be looking at the nutritional value of a bone meal fertilizer, why we need it for our garden, and when to use it. Read on and find out all these and more.

Benefits of bone meal to plants

Bone meal constitutes bones from animals and fish that are cooked, sterilized, and powdered. It is a pure organic fertilizer that gardeners have used in boosting crop productivity.

In other cases, you can purchase the product liquified or pressed into pellets with other supplementary nutrients. Naturally, it contains 15% phosphorous, 4% nitrogen, 24% calcium, iron, magnesium, and zinc. 

Here is a detailed post I wrote on Six critical nutrients that plants require to grow.

Bone Meal is a source of calcium for plants

Plants take up calcium from the soil through the roots, and it is transported through the xylem tissue to the rest of the plant.

Calcium is one of the essential plant nutrients. It performs crucial functions in the growth and development of plants: It provides structural support to plants’ cellular walls. Calcium is a significant component of cell walls and cell membranes, providing structural support to the plant.

Also, when a plant is stressed, calcium acts as a secondary messenger. Calcium is a counter-cation for organic and inorganic anions in the plant vacuole. It is an intracellular messenger in the cytosol: coordinates responses to environmental challenges and various developmental cues in plants.

Important to note is that excess calcium is toxic to plants. Certain enzymes in the plant help regulate the calcium levels in the plant, including Ca2+‐ATPases and H+/Ca2+‐antiporters.

Consequently, cytosolic Ca2+ is removed to the lumen of intracellular organelles and the apoplast.

These channels result in a condition that initiates cellular responses, which involve developmental cues and environmental challenges.

Upon binding with calcium ions, specific proteins change catalytic activity and conformation. These proteins, also termed as [Ca2+]cyt sensors, allow for transduction of the [Ca2+]cyt signal and cellular perception through a signaling and response network.

Calcium deficiency in plants

Although rare plants suffer from calcium deficiency, this commonly occurs from insufficient biological calcium in the soil or growth medium.  

Another common cause of calcium deficiency is low transpiration of either the whole plant or some parts. This is because calcium is only transported through the xylem tissues that also transport water through the plant and never transported through phloem tissues.

Calcium deficiencies resulting from low transpiration commonly occur in some plant tissues instead of the whole plant. These problems of low transpiration also result from the unavailability of enough water for the plant.

Water is also critical for the absorption of calcium ions by the plant through the roots. Whenever there is low moisture content in the soil, the plant does not get adequate calcium.

In other cases, the calcium in the soil is insoluble form, and for this reason, the plant cannot absorb it. One major cause of this is high phosphorous levels in the ground, which makes the calcium insoluble.

Problems with the transport proteins mentioned above also result in calcium deficiency in the plant.

Calcium deficiency in plants can also result from excess levels of nitrogen in the growth medium or soil.

Acidic and sandy soils contain low levels of calcium. If you grow your plants in such soils, you will need mineral supplements such as a bone meal.

Soils that have been exhausted by fertilizers are also more likely to have low levels of calcium.

Finally, calcium and magnesium need to be balanced in the plant. This is because the two ions are antagonistic and critical in plants’ growth and development. Too high levels of one could hinder the other.

Signs of calcium deficiency

Calcium deficiency in plants occurs in the form of localized tissue necrosis which causes stunted growth. The plant will also have curling leaves or necrotic leaf margins. This condition is common in tomatoes and is commonly referred to as blossom end rot.

Calcium deficiency first affects the new growth. As we saw earlier in this post, calcium is critical in forming new cells’ cell walls and cell membranes.

The condition spreads gradually in the plant, causing the death of root tips and terminal buds. The levels of calcium are higher in the older leaves and are hardly affected.

As a result of all these factors, plants with low calcium levels have reduced height, lesser nodes, and fewer leaves.

Different plants show different symptoms of calcium deficiency. For instance, apples will have a bitter pit, developing brown spots and pits on the skin and flesh. The condition commonly occurs during storage, and the affected areas are usually bitter.

In vegetables such as cabbage, brussels sprouts, and lettuce, calcium deficiency results in burned edges on the leaves or tip burn.

Calcium deficiency in carrots results in oval-shaped cavities, which create room for infections.

Bone Meal is a source of phosphorous for plants

Phosphorous ‘P’ is one of the major nutrients for plants and is found in all NPK fertilizers. It is among the 17 essential nutrients in plants. It is used in the conversion of other nutrients into more valuable elements.

In plants, phosphorous is critical in the growth of roots and flowering.

Plants require higher phosphorous levels than calcium, and plants are more likely to suffer from its deficiency. The concentration of phosphorus needed for optimum productivity is 0.1 to 0.5.

Plants absorb phosphorous from the soil through the roots as the primary orthophosphate ion (H2PO4 – ) and secondary orthophosphate (HPO4 =).

Mycorrhizal fungi are also critical in this process. The fungi grow in association with the plant roots of most plants.

Mycorrhizal fungi

Once absorbed, it is transported up the plant and used in a series of chemical reactions to form energy-rich phosphate compounds, including adenosine triphosphate (ATP). It is also used in the formation of enzymes, sugar phosphates, phospholipids, phosphoproteins and
Nucleic acids (DNA and RNA).

In all this, phosphorous helps in cell division, growth of seeds, the development of roots, and prevention of stunted growth in the plant. The excess phosphorous in the plant is then stored in the plant tissues for future use.  

Bone meal fertilizer contains high levels of phosphorous of about 15% of its total nutritional value. One advantage of using this bone meal fertilizer is that the plant’s phosphorous content is readily absorbed.

Certain crops that require high levels of phosphorous would immensely benefit from bone meal. These include potatoes, beets, and carrots. It helps in forming roots- thus critical in perennials in establishing roots during their first year.

Deficiency of phosphorous in plants

You can identify if your plants require additional phosphorous or bone meal fertilizer by conducting a soil test.

By observing your plants, you can tell when to add more bone meal fertilizer into the soil. Plants with this deficiency usually have a purple coloration around the stems, which results from the increased synthesis of anthocyanins.

Also, since this element is critical in the growth of new shoots, the plant will show stunted growth. Its leaves also turn dark, blue-green, and dull. In severe cases, the leaves may also go pale.

 In plants with phosphorous deficiency, the older plant parts are first affected. While the new growth appears perfectly healthy, it is usually smaller. In other plants, you will also notice that there is an increased root to shoot ratio.

Bone meal as a source of nitrogen

As we saw above, bone meal naturally contains 4% nitrogen. It is also common for manufacturers to add more nitrogen during processing. Nitrogen is a critical element in the growth and development of plants.

Unlike other high nitrogen fertilizers, which promote leaf formation at the expense of fruiting, bone meal provides plants with adequate nitrogen levels. However, the nitrogen needs vary depending on the soil type and type of plants.

Plants require nitrogen for growth, development, and reproduction. A healthy plant typically contains 3% to 4% nitrogen. The need for nitrogen for plants is much higher as compared to other nutrients.

It is used to form chlorophyll in sunlight, carbon dioxide, and water through photosynthesis.

Nitrogen is also a significant building block of amino acids that make up proteins.

Proteins are so critical in plants that plants with a deficiency of proteins die.  This is because proteins serve significant roles in plants, including structural units in plant cells and the formation of enzymes critical for metabolic processes.

Nitrogen is also an essential factor in transferring energy in plants in ATP (adenosine triphosphate).

Also, nitrogen helps in the formation of DNA and other nucleic acids. These genetic materials are critical in the growth and reproduction of plants.

Plants take up nitrogen in the form of ammonium ions and nitrates. Since nitrogen found in the atmosphere is not readily available to plants, there is a need to supplement these nitrogen levels.

Unlike ammonia that binds with soil particles, nitrate ions do not bind with soils, and plants can only absorb them when dissolved in water. For this reason, water is essential for the uptake of this ion. When the ground dries up, these ions form salt residues in the soil.

Plants low in levels of nitrogen will show stunted growth. On the other hand, adequate levels of nitrogen show in the formation of large and succulent foliage.

Other advantages of using bone meal

Bone meal fertilizer dissolves more slowly as compared to other fertilizers. For this reason, whenever you use it, it provides nutritional value to your garden for more extended periods.

Bone meal is quite helpful in blossoming and is used in flowering plants such as roses, Lillies, turnips, and dahlias.

Bone meal also contains other nutrients such as iron and zinc. Even though these components are required in smaller amounts, they are essential in the life of plants. Iron is critical in metabolic processes such as photosynthesis, respiration, and DNA synthesis.

Zinc is in the formation of some carbohydrates, chlorophyll, and the processing of starch into sugar. It is also critical in cold weather as it helps plants withstand frigid temperatures. Also, zinc is helpful in the formation of auxins that are responsible for the regulation of growth and stem elongation.

When should you use a bone meal?

Bone meal provides a long-term reserve for nutrients for your garden. You need to conduct a soil test to identify the missing nutrients to ascertain whether bonemeal is necessary.

A small amount of bone meal fertilizer goes a long way. You, therefore, need to use just half a teaspoon when planting by sprinkling on the topsoil. You can alternatively add the bone meal to compost before applying it to your garden.


A bone meal is suitable for your garden due to its lasting nutritional value. You can use it to grow a wide range of plants, including onions, potatoes, carrots, roses, turnips, and Lillies.

You might also want to read What is the difference between compost and fertilizer.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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