Bone Meal Explained: A Gardener’s Guide

By Erin Marissa Russell

Bone meal is one of your organic fertilizer options. It’s great in certain situations, but it doesn’t suit the needs of all plants or all gardens. Keep reading to learn what bone meal is good for (as well as its drawbacks), learn how to use it, and find out whether it’s right for you.

Bone meal’s main use is adding phosphorus to the soil. If your soil isn’t low in phosphorus, there’s no reason for you to use bone meal. Phosphorus helps make photosynthesis possible and boosts growth as well as helping plants make flowers and fruit. The NPK rating for bone meal is usually around 3-15-0. In addition to phosphorus, bone meal adds some calcium and nitrogen to the soil.

What Is Bone Meal?

As the name suggests, bone meal is made of bones. Usually, these are beef bones that are a byproduct of slaughterhouses. The bones are sterilized with hot steam and are then ground into meal for use in the garden.

Benefits of Using Bone Meal

Enhanced root production in young plants

Extra help against diseases and infestation

Increased yield of fruit and seeds

Increased microbial population in the soil, which can promote healthier soil structure

Healthier tomatoes, zucchini, peppers, and other veggies due to calcium content

Larger, more attractive blooms

Overall healthier and stronger growth

Usually an organic product

Drawbacks of Using Bone Meal

As a slow-release fertilizer, bone meal won’t give your plants a big nutrient boost right away.

Bone meal has a smell that can attract scavengers if the meal isn’t incorporated into the soil well. You should keep the bag stored in a tightly locking container or another safe place to prevent scavengers from tampering with it.

Bone meal is only effective in soil that has a pH level below 7.0. When the pH level goes above 7.0, plants won’t be able to access the nutrients in the bone meal.

Bone meal provides lots of phosphorus but is not a balanced fertilizer. If your plants are short on nitrogen or potassium, you’ll need to use bone meal in conjunction with another fertilizer.

If not mixed in well, bone meal can run into water supplies and cause a bloom of algae.

The scent of bone meal is attractive to dogs, but it can be dangerous for dogs to consume bone meal. It’s possible for bone meal to cause a blockage in their digestive system. Make sure that your bone meal is well mixed into your soil to prevent pets from consuming it.

Too much phosphorus in the soil can actually be bad for plants, and if you add bone meal when your soil isn’t low on phosphorus, the resulting overfertilization can harm your plants. Plants that are getting too much phosphorus can start to turn yellow, have stunted growth, or display other symptoms of overfertilization.

How to Use Bone Meal

Your first step should be testing your soil to make sure phosphorus is needed before you start using bone meal. You have the choice of going through a local Extension office or using a soil testing kit yourself. This searchable map from the National Pesticide Information Center will help you find your local Extension office if you need assistance.

You should also test the pH level of your soil to make sure it is 7 or below. PH levels above 7 will prevent your plants from being able to use the nutrients bone meal provides. Our article on how to test the pH level of your soil will help you if you aren’t sure how to do this. If your pH level comes back as 7 or above, there are steps you can take to amend your soil and change the pH level. Address the pH level of the soil before attempting to use bone meal if your pH level is 7 or higher.

You should always choose a day with a dry forecast to work with bone meal in your garden. When the soil is too moist, it makes it difficult to mix in any amendments, bone meal included.

There are several ways to apply bone meal, but no matter which you use, your ratio should be one tablespoon of bone meal per two square feet of soil (or three cups of bone meal per 100 square feet of soil). However, check the packaging of your bone meal, as the manufacturer may have provided their own instructions. If your instructions contradict the ratio we’ve provided, follow the manufacturer’s instructions instead.

You can use bone meal while you’re planting by adding the bone meal to the backfill soil you’ll use. Alternatively, you can add bone meal after digging the hole for your plant, dropping the bone meal into the hole and digging it into the soil a bit before adding your plant and backfilling with soil. The proper ratio is just a few tablespoons per plant.

But if your plants are already in the ground, you can amend with bone meal by adding it on top of the soil and then using a rake to gently mix the bone meal into the top level of soil.

Always water after you’ve added bone meal to the soil, to help it stay in place and begin to break it down. It takes bone meal about four months to break down and completely release its nutrients into the soil.

Now that you know exactly when and how to use bone meal in your garden, you can make an informed decision about whether or not it’s right for you.