How to Make Bone Meal Fertilizer From Kitchen Leftovers

Bone meal is something that we all have heard of, and many of us are spending big bucks using it to increase phosphorus and add calcium to the soil. But did you know you can make it for free with leftovers?! 

When our family cooks a turkey or chicken for dinner, I don’t like to let any part of the animal go to waste! After using up the meat, I boil the scraps to make bone broth, and then process the bones into DIY organic fertilizer for our farm and garden.

By learning how to make bone meal, kitchen scraps can be converted into something useful that can help you save money, reduce waste, and grow bigger!

Waste Not, Want Not

Something is only truly wasted if we don’t find a use for it! We can reduce waste by being resourceful and mindful of our every day choices.

Making plant food out of things we would normally throw away is a great place to start! By learning how to make compost, homemade compost tea, liquid seaweed fertilizer, vermicompost, and bone meal for fertilizing an organic garden, you can stretch your resources and your dollars a lot further.

What is Bone Meal

Bone meal is an organic powder made from pulverized animal bones. It is considered a slow-release fertilizer with two primary functions: to increase root development and boost flower production. It can be used on its own as a soil amendment, or as part of a fertilizer mix. 

Why Does Bone Meal Make Good Fertilizer

When you look at a bag of fertilizer, you'll see the NPK labeled as three numbers. NPK stands for nitrogen (N), phosphorus (P), and potassium (K), the three predominant macronutrients needed by plants.

Bone meal is known for its high levels of phosphorus, the middle number in fertilizer labels. If you have one pound of bone meal, 12% of the pound is pure phosphorus, and 1% is nitrogen, but it is also a great source of calcium and other minerals. It’s absolutely incredible!

That’s why bone meal is one of the ingredients in MIgardener’s Trifecta fertilizer. While most fertilizers are made for specific varieties, Trifecta is a soil supercharger that can be used on any plant in the garden!

I understand that some people don’t like using animal products in their garden, and I respect that. If you or someone you know grows veganically, MIgardener also has a great vegan fertilizer called VegaGrow that is all mineral-based with no animal byproducts. Check it out; you might love it.

Supplies Needed

To make bone meal, you will need:

• Bones - I typically use turkey or chicken bones, but you can use other bones leftover from your meals.

• Heavy Duty Foil Pan - I like to use a heavy duty foil baking pan or a cookie sheet lined with aluminum foil for cooking the bones.

• Oven - A kitchen oven works great for drying out the bones, but a pressure cooker can also be used.

• Blender - A heavy-duty blender should work to pulverize the dried bones into meal. Pro-Tip: I definitely recommend getting a spare blender for this, instead of using your nicest kitchen blender. We got ourselves a Blendtec, which is nice and hardy, for making bone meal.

• Sawdust - Adding sawdust as an anti-clumping agent is optional. 

How to Make Bone Meal

Before making bone meal, I highly recommend using leftover bones to make bone broth first! Bone broth is high in protein and collagen and great for fighting off a cold or boosting your immune system! 

We love to use it for making soup or sipping on a cold winter’s day. Pro-Tip: Don’t add salt to the broth until after you’ve removed the bones. You don’t want to add salt to your garden soil in your bone meal!

Then, follow these instructions on how to make bone meal:

1. Bake - Preheat an oven to 350°F. Put the chicken or turkey bones in an aluminum pan or on a foil-lined baking sheet and place in the oven for 30 to 45 minutes. Pro-Tip: Larger bones like beef or venison will likely take a lot more cooking time. You may even want to use a pressure cooker instead of an oven to speed things up.

2. Test - Take the bones out of the oven and do a “break” test to check the moisture content. If the bones are dry enough, they will be brittle and break quickly and cleanly instead of bending before breaking. The dryer you get the bones, the better! (Put the bones back in the oven if needed until they reach the desired dryness.)

3. Clean - You don’t want to make the bone meal with the remaining bits of fat, skin, meat, or tissue still on the bones. Making bone broth first will often clean a lot of that off the bones, but anything that remains should now be picked off. This will make a cleaner, better product that is less likely to attract animals to your garden when you use it.

4. Pulverize - Place the dried bones in a heavy-duty blender and grind them into a powder. Pro-Tip: A heavy-duty blender should be able to handle chicken and turkey bones, but you will need to find another way to grind bones that are 1” in diameter or bigger. 

5. Add Sawdust - This step is optional. Add about ¼ cup of sawdust for every 1 ½ cups of bone meal if the bone meal is clumpy. The sawdust will act as an anti-clumping agent and absorb excess oil and grease.

How to Use Bone Meal As Fertilizer

Bone meal can be stored in an airtight container until you are ready to use it. It doesn’t have an expiration time and does not lose its nutrient value over time, but can be stored indefinitely if it is kept cool and dry. 

When you are ready to use it, top dress established plants with 1/2 Tbsp per plant or about a half of cup per square foot and gently rake it in. 

As always, it’s a good practice to test your soil first to determine what your soil actually needs before amending. I like to keep the Rapitest Soil Test Kit on hand because it is inexpensive and has 40 tests,10 each for testing pH, nitrogen, phosphorus, and potassium.