What Fertilizer Is High In Phosphorus? You Should Use These. | GreenUpSide (2024)

If a soil test reveals that your soil is lacking phosphorus,then you are probably looking for a way to supplement this important nutrientin your garden. Luckily, there are manyoptions for high-phosphorus fertilizers.

So, what fertilizer is high in phosphorus? Fertilizersthat are high in phosphorus include mushroom compost, hair, rock phosphate,bone meal, burned cucumber skins, bat guano, fish meal, cottonseed meal, wormcastings, blood meal, manure, and compost.

Of course, you can use a mixture of any of these sources of phosphorus, depending on what you have available. You can also use fertilizers formulated as bloom or blossom boosters, which will have high phosphorus content.

Let’s get into more detail about just how much phosphorus each of these fertilizers contains, and how long it takes them to release into the soil.

(You can also watch my YouTube video on this topic if you prefer!)

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What Fertilizer Is High In Phosphorus?

Here is a table with some of the best fertilizers with high phosphorus content. You can find more detail about each type of fertilizer after the table.

Note the numbers given in the table are percentages by weight, and that N = Nitrogen, P = Phosphorus, and K = Potassium. (You can learn more about NPK nutrients on fertilizer labels in my article here).

For more information, check out this article on NPK values of fertilizers from the Oregon State University Extension.

Hair

Hair may not be the first thing you think of when you are lookingfor fertilizer for your garden. However,hair is 26% phosphorus by weight, meaning that it has the most phosphorus,pound-for-pound, out of any of the other fertilizers listed here.

Hair is a very slow release fertilizer, and is effective for4 to 12 months. However, it isrelatively easy to find, since it is a waste product of every barbershop.

The only problem is that hair from barbershops will oftencontain chemicals, such as hair spray or gel, which you may not want to mixinto your garden soil.

Instead of applying hair directly into your soil, your bestbet is to put it into a compost pile, along with some of the other phosphorussources here. That way, it can breakdown over the course of several months to a year.

Hair also contains 12% nitrogen by weight, although it doesnot contain any potassium.

Enriched Rock Phosphate

Rock phosphate, also known as phosphorite, is a sedimentaryrock with a high phosphorus content by weight.At 17 to 30% phosphorus by weight, enriched rock phosphate is one of thebest sources of phosphate for growing crops.

Rock phosphate is often found in limestone and othersedimentary rocks. Rock phosphate has avery slow release time, and is effective for 5 or more years.

There are better sources of phosphate if you want a quick releaseof phosphorus into your soil. However, rockphosphate is a great source of phosphate if you want to apply it once and notneed to do it again for year.

For more information, check out this article on rock phosphate from Wikipedia.

Keep in mind that rock phosphate contains no nitrogen orpotassium.

Bone Meal

Bone meal is made from crushed or ground bones and wasteproducts from slaughterhouses. At 15% to27% phosphorus by weight, it is just behind enriched rock phosphate in terms ofphosphorus content.

Bone meal has a medium release time, and is effective foronly about 6 weeks. One caution aboutbone meal is that it may burn plants if used in high amounts.

Instead of applying bone meal directly to plants, add it toyour compost pile, along with some of the other fertilizers in this list. After a few months to a year, you will have abalanced compost mix with plenty of nutrients for your plants.

Remember that plants can only get phosphorus from bone mealif the soil pH is below 7.0 (acidic). Theonly way to tell for sure is to do a soil test (more on this later).

In addition to phosphorus, bone meal contains plenty ofcalcium, along with 2% to 6% nitrogen by weight. However, it contains no potassium.

For more information, check out this article on bone meal from Wikipedia.

Burned Cucumber Skins

This is one of the most surprising high-phosphorusfertilizers on this list. Burnedcucumber skins contain 11% phosphorus by weight, making them a fairly goodsource of phosphorus on a pound-for-pound basis.

Burned cucumber skins also have a fast release time, meaningthat they are effective for only a few weeks.

In addition to phosphorus, burned cucumber skins contain 27%potassium, making them a champion for providing this nutrient as well. Burned cucumber skins contain no nitrogen,however.

You can ask a local restaurant if they have cucumber skinsavailable, since they will peel and slice many of them in the course of a dayfor salads.

Bat Guano

Guano is the excrement of seabirds and bats. Bat guano is a fairly good source ofphosphorus, containing 4% to 11% phosphorus by weight.

It is difficult to find bat guano on your own, so you willprobably need to buy it from a store or online.

Bat guano has a medium release time, and is effective forperhaps a month or two.

One caution is that bat guano has a low pH (very acidic), soit should be used with caution to avoid burning your plants with a suddenchange in pH.

Only use bat guano directly in soils with high pH, or elsemix it into your compost pile to dilute the acidity.

Here is a fun fact for you: bat guano that accumulates overmany years can eventually provide a source of rock phosphate once the excrementhardens into layers of rock!

Bat guano also contains 12.3% nitrogen and 2.5% potassium byweight, making it a great all-around fertilizer that provides plenty of eachnutrient.

For more information, check out this article on guano from Wikipedia.

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Fish Meal

Fish meal is a powder made from ground up fish parts,including bones. Fish meal is a goodsource of phosphorus, containing 4% to 6% phosphorus by weight.

Fish meal has a medium release time, and is effective for 4to 6 months.

Dry fish meal also contains 10% nitrogen by weight, althoughit does not contain any potassium.

For more information, check out this article on fish meal from Wikipedia.

Cottonseed Meal

Cottonseed meal is what remains after cottonseed oil isextracted from cotton seeds. Cottonseedmeal has a 2.5% to 3% phosphorus, making it better than most manures in termsof phosphorus content by weight.

Cottonseed meal has a slow to medium release time, and is effectivefor 4 to 6 weeks. Remember thatcottonseed oil is somewhat acidic, so it may be a good idea to mix it intocompost instead of using it directly on plants.

Cottonseed oil also contains 4% to 6% nitrogen by weight and1.6% potassium by weight, making it a good all-around source of the big threenutrients.

For more information, check out this article on cottonseed meal from Wikipedia.

Worm Castings

Worm castings are the product of vermicomposting, whereworms are used to help decompose vegetables and food waste. Worm castings contain plenty of organicmaterial, in addition to their nutrient content.

Worm castings contain 2.5% phosphorus by weight. In addition, worm castings contain 1.5% nitrogen and 1.3% potassium by weight.

For more information, check out this article on vermicompost from Wikipedia.

Blood Meal

Blood meal is a powder made from the dried blood of animals(often cattle or hogs), and like bone meal, is often a by-product ofslaughterhouses.

Blood meal contains 1.5% phosphorus, making it better thanmost manures and composts in terms of percentage phosphorus by weight.

Blood meal has a medium release time, and is effective for 6to 8 weeks.

Blood meal also contains 12.5% nitrogen and 0.6% potassiumby weight.

For more information, check out this article on blood meal from Wikipedia.

Manure

There are many different types of manure, including cow,horse, pig, and chicken.

Cow and horse manure often contains only 0.2% to 0.7%phosphorus by weight.

Pig manure contains 0.5% to 1% phosphorus by weight.

Chicken manure contains 1% to 4% phosphorus by weight.

All of these manures have a medium release speed, and can beeffective for two years.

Manures also contain small amounts of nitrogen and potassiumas well, making them good all-around fertilizers. Just make sure to decompose manure completelybefore using it on your garden, to avoid burning your plants!

For more information, check out my article on manure.

Compost

Compost is made from kitchen scraps and yard waste, such asbanana peels, orange rinds, grass clippings, and raked leaves.

Compost contains 0.5% to 1% phosphorus. It is a slow release fertilizer, and alsocontains nitrogen and potassium.

The best part about compost is that you can make your own in your backyard. For more information, check out my article on how to make compost.

Fertilizer For Flowering Plants

These specialized fertilizers contain more phosphorus than nitrogenor potassium. They are often labelled asblossom boosters or bloom boosters.

For example, Triple Super Phosphate from Easy Peasy Plantscontains 44% phosphorus by weight. It issupposed to help with root growth, in addition to aiding fruit and flowerformation.

You can check out Triple Super Phosphate on Amazon.

If you want a more balanced high-phosphorus fertilizer, youcan use something like Gaviota 10-30-10 fertilizer.

You can check out Gaviota 10-30-10 fertilizer on the Home Depot website.

Can You Have Too Much Phosphorus In Soil?

Yes, it is possible to have too much phosphorus in your soil. Excessive phosphorus in soil can cause stuntedplant growth by preventing plants from absorbing nitrogen.

However, there are other problems with excessive phosphorusin soil.

First of all, the excess phosphorus can move into ponds, lakes, streams, or rivers via runoff water, threatening water quality by causing algae blooms.

Excess phosphorus can also inhibit growth of beneficialbacteria in soil.

For more information, check out this article from UMass Amherst on too much phosphorus in soil.

The moral of the story is this: always get a soil testbefore adding any supplements to your soil.Make sure you really do have a phosphorus deficiency!

A soil test will also tell you if your soil is too acidic(low pH) or too basic (high pH), which can help you to decide which supplementto use.

For more information, check out my article on how to do a soil test.

Conclusion

Now you have a much better idea of which fertilizers (both natural and man-made) have high phosphorus content by weight. You also know how to choose which one to use based on the time it takes for the fertilizers to release nutrients.

Just remember that high phosphorus levels in water can cause algae growth on the water, or on the surface of soil, or in a greenhouse.

Also, keep in mind that cold soil can cause phosphorus deficiency in plants – even if there is plenty of phosphorus in the soil. For example, the leaves of tomato plants will turn purple due to phosphorus deficiency caused by cold soil.

If you want some ideas for how to add nutrients to your garden soil naturally, check out my article here.

You might also want to check out my article on fertilizers that are high in potassium.

I hope you found this article helpful – if so, please share it with someone else who can use the information.

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