What Is Bone Meal Fertilizer Used For? A Complete Guide

When you want good strong roots, big blooms and fantastic fruit, applying a good high phosphorus fertilizer is going to get the job done. Of all the option available on the market today, none can hold a candle to bone meal. It’s an all-natural, sustainable source of both phosphorus and calcium, a choice that’s stood the test of time.

Miracle Grow Bone Meal
Miracle Grow Bone Meal

What is bone meal used for?

Bone meal fertilizers are rich in phosphorus and calcium, making them ideal for heavy bloomers and abundant production of fruit. They are especially useful for nightshades, like tomatoes and peppers. Care must be taken in their application, as too much phosphorus can cause environmental problems, and the odor of bone can attract unwanted pests.

What is bone meal made of?

Bone meal really isn’t hiding anything in its name. It’s made of discarded animal bones, the leftovers of the meat industry. They’re heat treated to kill off any nasties that may be lingering, and ground into a fine-grained meal.

It sounds pretty grim, but it’s actually a very thrifty and sustainable choice. Those bones don’t have many other uses, so returning them to the land, one handful at a time, is a far more dignified choice than tossing the lot into landfill. It’s a good choice for the Earth and your garden.

What is the nutrient composition of bone meal?

Bone meal is fantastic stuff. It’s rich in phosphorus, and as far as calcium supplements for your garden it’s hard to beat.

The exact composition of any given bone meal product varies quite a bit depending on the brand. But in general, you can expect an NPK of around 3-15-0.

Around three percent of the mass is nitrogen, key to healthy leaves and stems. Fifteen percent is phosphorus, critical for photosynthesis, and is also needed in abundance for good blossoms and fruiting as well as root development.

NPK doesn’t tell us the whole story. It’s also rich in calcium, with a typical brand containing around 15% by weight. Given that calcium is critical for building strong cell walls and enzyme function, it’s also essential for good growth.

Which plants benefit from using bone meal?:

1. Tomatoes

Unripe Cherry Tomatoes
Unripe Cherry Tomatoes

Tomatoes are a prime candidate for judicious application of bone meal. They’re hungry customers, needing lots of phosphorus and calcium to produce flowers and their fat red fruit in time

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For bedded plants, a good tablespoon mixed into the soil just head of planting will prepare the ground for a bountiful harvest. When growing in containers less is needed, about a teaspoon or so depending on the size of the container and the strength of the product.

2. Peppers

Doe Hill Heirloom Peppers
Doe Hill Heirloom Pepper Plants

It’s no secret I love to grow peppers, and have found bone meal to be an excellent tool in my chest. These fiery wonders are heavy feeders with a powerful need for extra phosphorus over the growing season. They’re also susceptible to blossom end rot, a disease that can be remediated with a good dose of calcium.

Like tomatoes, mix a teaspoon into their bed before planting for best results, watering in well.

3. Bulbs

Bone meal granules 1
Bone meal granules applied to garlic bulbs

It’s basically traditional these days to dose a new planting of spring bulbs with bone meal. While the bulb has everything it needs within to produce a new plant, by the time it’s ready to flower it’ll want a bit of extra support.

Typically, a teaspoon or so per bulb added into the bottom of planting holes is ideal. Be sure to turn it through the soil well and water heavily. That will help it support those emerging roots, and be ready and waiting for flowering. I always make sure to add a few scoops of bone meal to my garlic bulbs before planting in the fall.  

The drawbacks of using bone meal

Bone meal is a high phosphorus fertilizer, and not all soils need that extra dose. Phosphorus and calcium are both immobile – it means they tend to stay put. If you fertilize regularly with a more balanced fertilizer, you may find you can skip applying bone meal all together and put that time and money to better use.

It really pays to have your garden soil tested before applying rich fertilizers. Most county extension services offer low cost soil testing, and can provide you with a detailed report of your soil’s contents that can help guide your gardening. You can find your closest extension office here.

You can also perform home tests that are as easy as dipping a stick in a jar. They’re readily available on Amazon, or at your local garden supply store.

For leafy green vegetables

Over wintered kale
Over wintered kale

While leafy greens like lettuces, spinach and kale also need phosphorus and calcium, the need nitrogen far more. Bone meal’s low 3% nitrogen by weight just isn’t enough to keep those delicious crops coming.

You really need a high nitrogen fertilizer for these crops to make the most of them, or at the very least something with a more appropriate ratio. A 16-4-8 fertilizer is a good choice. It’ll provide a solid supply of nitrogen while still providing the a more appropriate dose of phosphorus.

When trying to keep pests away

The delectable scent of buried bone attracting dogs is the stuff of cartoon legend, but it contains a germ of truth. The scent of animal waste scattered across your garden bed may well prove irresistible to wild animals, drawing them to your garden. Once in the location of this tantalizing scent, they’ll dig away in search of a meal.

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If you have raccoons, coyotes and other critters in your area that love to scavenge up a meal, it’s better to skip slaughterhouse fertilizers like bone meals. Stick to less appealing sources of phosphorus, like synthetic phosphates, manures or even bat guano. For calcium, a calmag solution will get the job done with far less risk.

When phosphorus levels are sufficient

“When excessive application occurs, phosphorus may accumulate in the soil and exit the plant-soil system. At this point, phosphorus can become a water quality concern, causing excessive growth of algae and aquatic vegetation. The first step for keeping phosphorus in the field and out of surface waters is to soil test and maintain phosphorus at a soil nutrient level that supports plant growth but does not accumulate excessively beyond optimal levels.”

Marilyn Thelen, Michigan State University Extension Officer

Too much phosphorus in the soil can cause substantial problems. It locks up zinc, iron, and other essential metals, so too much can result in deficiency diseases. It also interferes with a plant’s ability to form partnerships with fungi in the soil, forcing them to spend more energy than otherwise needed to spread their roots.

It’s a substantial environmental hazard, too. Excess phosphorus also has a nasty habit of leaching from soils in prolonged rain or under  heavy irrigation. Once there, they upset the ecosystem, causing blooms of plant life that suck oxygen from the water once they die and start to decompose. This is known as eutrophication, and has a devastating impact on our wild places.

How and When to apply bone meal

Bone meal bag with broccoli 1
Bone meal bag with broccoli

Bone meal is best applied before they really get those roots going, so aim to get it in the ground early in the season before planting or sprouting.

It also needs to be well mixed through the soil too. Use a rake or hoe to turn it through the top inch or so of soil, ensuring an even distribution. Once you’re confident it’s mixed in well, water heavily to get the nutrient release process started.

Where to buy bone meal

Bone meal is readily available at most garden supply stores, but I find it easiest to just order online. Here’s some of my picks.

For tomatoes, peppers and potatoes

FoxFarm Happy Frog Steamed Bone Meal Fertilizer is my pick for hungry veggies like tomatoes, spuds and my beloved peppers. Not only does it contain that all important phosphorus and calcium, but it’s also enriched with friendly soil fungi known as mycorrhiza. These little helpers work with the plants’ roots, enabling them to get every scrap of nutrition they need to produce spectacular crops.

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For bulbs

Bulbs don’t need much, so for them I suggest an organic, granular formulation that will release slowly through the soil. Down to Earth Organic Bone Meal Fertilizer is a certified organic, free of any synthetic nasties or additives. It’s about as close as you get to a traditional style bone meal, perfect to get those bright blossoms nodding in the wind come spring.

For containers

It pays to be gentler with container gardening, as any input is going to stay trapped hard against the roots. For this reason, I suggest Jobe’s Bone Meal Fertilizer Spikes for container grown plants in need of a boost.

Unlike most bone meals, you don’t need to rake them in, which is perfect for potted plants and container gardens. They’re also specifically formulated with containers in mind, and list the dose per inch of pot rather than area or volume.

FAQ:

Can bone meal burn plants?

Like any nitrogen bearing fertilizer, bone meal can absolutely burn your plants if used improperly. It needs to be mixed into soils and watered well during application. This allows the material to blend seamlessly with the rest of the components beneath the ground, avoiding big chunks that can cause problems for sensitive plant tissue.

Can you use bone meal during flowering?

If you are aiming for flowers, then adding bone meal only once the flowers have arrived is probably redundant. They’ve bloomed, their work is done, and so you’ll need to wait until next spring before you dose again.

But if your flowers are just the start, and you’re hoping for fruit, a gentle top up of bone meal isn’t out of the question. This is especially true if we’re talking about tomatoes or peppers. The extra calcium may mean the difference between a vibrant, delectable summer crop or a mess of half rotten failures.

What does bone meal do to potted plants?

Bone meal does much the same thing to potted plants as it does to those in the ground – provides a slow release source of phosphorus and calcium.

You do have to be more cautious using bone meal for potted plants, however. It’s easy to overload a container with too much phosphorus, and most potted plants need even less than those in beds. Potting blends tend to be very nutritious, and plants need very little phosphorus.

That said, tomatoes, peppers and big bloomers will all benefit from a modest bit of bone meal at the start of the season. Spikes like the ones I recommend above are fantastic for this, as they release very slowly and won’t compromise your soil chemistry.

Final thoughts

I’m always hunting for reliable, natural solutions to my garden’s nutritional needs. Bone meal hits all the right buttons – it’s sustainably sourced, organic, and a tested and true option for my hungry peppers and tomatoes.

Brock

Brock is the head gardener and writer behind Bigger Garden. Every year you can expect to see something new in his raised beds, from purple broccoli to cotton candy peppers.

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