23 Organic Fertilizer Types and How To Use Them
If your plants are struggling to grow, you might need to amend your soil with organic fertilizer. Learn about them and how to use them here.
If the plants in your vegetable garden keep dropping leaves, turning odd colors and generally failing to thrive, it might not be your gardening techniques that are at fault.
There could be an imbalance in your soil structure that’s killing your garden plants. In such instances, improving your soil fertility might simultaneously improve your chances at having a successful garden. However, it’s always a good idea to test the pH levels and the soil acidity in your garden before you start applying fertilizer. Too much of a good thing can easily be as bad as a hands-off approach.
For instance, phosphorus, which is a main component of most fertilizers, will only work at a certain pH range. Adding unnecessary nutrients or organic material can also cause environmental problems since these compounds get washed away in heavy rains and pollute nearby waterways.
Before we get into it, note that the Epic Gardening Shop stocks a few of the best organic soils, amendments, and fertilizers that we personally use. So if you want something pre-formulated, we’ve got you covered!
Synthetic vs. Organic Fertilizers
Like most organisms, plants need a variety of nutrients in order to grow properly. These soil microbes are normally present in healthy soil. When they are not, the plants suffer. Fertilizers were created to make up for any soil deficiencies so that things can be grown in less-than-ideal spaces. However, the main nutrients found in fertilizer are nitrogen (N), phosphorus (P), and potassium (K). They’re generally listed on labels in that order as well.
Of course, the difference between synthetic and organic fertilizers doesn’t seem significant, but you will see differences, particularly in the long run. Synthetic fertilizers are known to degrade the quality of soil over time, damaging human health in the process. You constantly need more synthetic fertilizers to improve your garden. Synthetic fertilizers also contain salts. These compounds not only make the soil more acidic, they keep beneficial earthworms away. Not the best option for organic gardening.
Regular watering of your plants can even move the nutrients in these compounds far enough from the plant roots that they negatively affect root growth. In addition, synthetic fertilizers are often made from non-renewable resources rather than organic matter. Organic fertilizer for plant well-being is more effective.
What is organic fertilizer? Organic fertilizers improve garden soil microbes where they are used. They not only assist with water retention, they also make the soil lighter so that more air is available to the plant roots. They don’t waste nutrients like chemical fertilizers. Nor are they likely to create a build-up of salts that could dampen plant growth. These types of fertilizers even tend to be less likely to burn tender plant roots than synthetic products.
The slow-working nature of organic fertilizers is beneficial if you’re looking to improve your garden soil over time. This aspect can nonetheless be a downside if you’re looking for instant results. A good organic compromise when your plants need a sudden energy boost is liquid fertilizers or foliar sprays. Gardeners should also be aware that organic fertilizers are biologically active, unlike inactive inorganic fertilizers, which may also come from natural sources.
This means that their components can change over time and may vary slightly with each batch. They’re not as consistent as chemical fertilizers, but high-quality organic fertilizers are more bioavailable to your plants. That’s why they’re perfect for organic gardening.
You do need to be careful when it comes to purchasing fertilizer. Those products stating they are ‘organic’ at first glance might not actually be. Make sure you read product labels carefully. A good way to judge claims for accuracy is to check the one you plan to buy against the Organic Materials Review Institute’s list. However, if you’re not a commercial grower, keep in mind that all the products listed here are also considered organic.
Types of Organic Fertilizers
Here are the basic types of natural fertilizers you’ll find on the market. When it comes to fertilizing organic garden spaces, there are options! Organic garden fertilizers have many forms.
Exactly what it says on the tin, dry fertilizers are often mixed into the soil. These organic fertilizers can be used on both in-ground gardens and container-grown plants. Types of fertilizers in the dry organic matter category are generally added as a way of encouraging long-term growth in seedlings, transplants, and crops. Usually, they mean to improve soil structure.
Obviously, these are liquid organic fertilizer applied as a soil fertilizer or leaf feed. They may additionally use a type of binding agent to help them be better absorbed by the plant or soil structure in question. These fertilizers might be poured onto the soil surrounding the plant so that they can be absorbed roots. Or they could be sprayed on the leaves instead. After all, foliar (leaf) sprays are particularly useful for vegetables during their season.
Liquid fertilizers are generally considered good organic fertilizers for plants that are actively growing and should usually be applied on a monthly basis. However, leafy crops might need to be sprayed on a biweekly basis. You can still practice organic gardening while regularly applying organic matter fertilizer on a consistent schedule, though.
While they aren’t fertilizers per se, these substances help plants absorb nutrients that they receive from elsewhere. Some of them, such as kelp, are also a great source of trace elements. However, paying for these elements to be included in your fertilizer can be a waste of money since healthy soil should already contain helpful organic matter such as microbes, enzymes, and humic acids.
How to Use Organic Fertilizer
You pretty much use organic fertilizers in organic gardening in the same way you would use regular chemical fertilizers. If you are buying premade organic fertilizers, the process is fairly simple. Read the instructions on the box and err on the side of caution when you’re deciding how much to apply. (Hint: it’s always a good idea to avoid using strong-smelling products like fish emulsion fertilizer indoors.)
However, if you want to mix up your own for a specific garden need that you have, you can certainly do that as well by combining different sources of organic matter into one solution. Just be careful not to overdo it in order to not burn plant roots or even kill sensitive plants. When used properly, they are excellent for a garden and attract beneficial insects and critters, unlike chemical fertilizers.
List of Organic Fertilizers
Now we’ve made it to the organic fertilizer list. There may be some that act as a high nitrogen organic fertilizer, while others are more of a high phosphorus fertilizer. All are considered organic due to their source. Organic gardening fertilizer has tons of shapes and sizes. Read through this to determine which bio-fertilizer is best for your garden.
NPK Ratio: 2-0-1
Alfalfa is an organic fertilizer commonly used as part of livestock feed. However, alfalfa meal is a natural fertilizer simply ground up so that it breaks down faster. This particular organic fertilizer has low amounts of nitrogen, phosphorus, and potassium. As a result, alfalfa meal works to improve plant health at a moderate rate of speed compared to other organic fertilizers. In organic gardening, the best use for these is as soil conditioners in the early spring prior to planting. It’s a great organic fertilizer for vegetables, acting as a slow-release bumper crop if you grow it and then chop and drop it between vegetable plantings. Among organic plant fertilizers, this source is often used in agricultural fields just as nature intended.
Recommendation: Down To Earth Alfalfa Meal, 4lb
NPK Ratio: 6-2-1
The organic nutrients in this fertilizer have plenty of nitrogen, but it also contains fair amounts of potassium and phosphorus. The downsides to cottonseed meal are that it works slowly and that it is available primarily in cotton-growing areas. In organic gardening, this fertilizer is particularly useful for conditioning gardens in the fall before cover crops are planted or before mulch is applied. This gives the cotton seed meal time to break down fully so that the nitrogen present is readily available in the spring.
Recommendation: Down To Earth Cottonseed Meal, 5lb
Corn Gluten Meal
NPK Ratio: 9-0-0
Corn gluten meal contains trace amounts of nitrogen, phosphorous, and potassium. It is also a good soil stabilizer, but it works slowly, feeding beneficial microbes in the soil. Therefore, you should add it in the fall so that it has time to break down over the winter. However, if you do add it during an active organic gardening season, know that it won’t burn plant roots.
Recommendation: Walt’s Corn Gluten Meal, 20lb
NPK Ratio: 0-3-0
Rock phosphate is made from rocks that have been ground up. It contains large amounts of phosphate as well as other essential nutrients. The main benefit of using this fertilizer is that the elements it contains don’t dissolve in water. Instead, they hang around in the soil until they’re used by the plants that are growing there. This is perfect for someone with an organic gardening practice that strives to be ecologically sensitive.
Recommendation: Down To Earth Rock Phosphate, 5lb
NPK Ratio: 0.5-0.5-0.5
Animal waste, in general, has a high mass-to-nutrients ratio. It nonetheless contains respectable amounts of nitrogen, phosphorus, and potassium. Cow manure (aka cattle manure) also works on gardens at a moderate rate of speed. These elements all help to make it an excellent compost additive. However, some weed seeds may survive being digested by the cows in question, and this can cause obvious problems. You should also avoid manure leftover from industrial operations because it contains lots of salt. Fresh manure that hasn’t composted enough has too much plant nutrition and can burn roots. Even regular manure can end up burning plants if too much is used or if it’s used too often. In organic gardening, use manure sparingly.
Recommendation: Black Kow Composted Cow Manure, 4lb
Chicken or Poultry Manure
NPK Ratio: 5-3-2
Having a lot of poultry crap or chicken manure on hand doesn’t mean that you’ll get comparatively high nutrient levels. Even so, poultry or chicken manure contains slightly higher amounts of the three main plant nutrients than cow dung does. It’s often considered the highest nitrogen organic fertilizer. It also works in a somewhat faster fashion. The best time to use poultry or chicken manure is just after harvesting your crops or just before you begin another gardening cycle. As is the case with cow manure, you’ll want to be careful with chicken manure, turkey manure, or fowl manure because it can burn your plants if too much is applied. This starter fertilizer is one of those soil amendments that supports soil organisms that increase nitrogen uptake in the roots of your garden plants.
Recommendation: Espoma 5-3-2 Chicken Manure, 25lb
NPK Ratio: 2-1-1
Earthworm castings contain decent amounts of all three vital nutrients. As a result, this type of fertilizer is considered a great addition to flower and vegetable gardens, increasing aeration and nutrient availability in soil biology overall. Worm castings are the star of many organic production sites. We have a great piece on worm castings. Check it out!
Recommendation: Urban Worm Company Worm Castings
NPK Ratio: 1-1-5
Greensand comes from ancient sea beds. This high-calcium fertilizer also contains iron, potassium, and other trace elements. However, the nutrient levels in glauconite (greensand) products can vary depending on their source.
Recommendation: Down To Earth Greensand Soil Conditioner, 5lb
NPK Ratio: 2-1.5-1.5
Compost’s nutrient profile varies based on what is put into, but it is often close to that of manure. It is a popular garden fertilizer and perhaps the best organic fertilizer out there. This is never in doubt because it can be made for free, and it works at a moderate pace. There are also a variety of ways that compost can be used in your garden. It can be used as a mulch or mixed with your garden soil. It can also be brewed into compost tea to use as a foliar feed. Gardeners who don’t have space for a large compost system can even get similar benefits from using worm compost bins under their sinks.
However, compost can be alkaline in nature. This characteristic negatively affects how well plants living in the soil can absorb nutrients. Compost also has a high weight-to-available-nutrient ratio. Improperly tended compost piles can additionally emit bad smells, which can quickly get city dwellers in trouble with their neighbors. This is especially true when sewage sludge is composted for a short time and used in gardens. Humanure should be composted for at least a few years before it’s used in a garden.
If you still plan on using it, compost should be added before or after planting. It’s also a good soil refresher in between growing seasons for gardens that are constantly in use. You’ll want to use half an inch to a full inch every time a new crop is planted. If you’re having consistent issues with your plants after applying compost, do a soil test to see if you can identify if the compost is the problem.
Recommendation: Michigan Peat Garden Magic Compost, 40lb
NPK Ratio: 7-2-0
Soybean meal is a high-nitrogen fertilizer that also contains low amounts of phosphorus and calcium. Local growing conditions tend to affect how fast this product is absorbed into the soil, but this process normally occurs at moderate rates of speed. However, soybean meal is fairly useful as a long-term soil conditioner.
Recommendation: Down To Earth Organic Soybean Meal, 5lb.
NPK Ratio: 12-1.5-0.5
This fertilizer is created from the powdered blood of butchered livestock. While it is high in nitrogen, blood meal is low in other elements. It is also highly acidic and likely to burn plants if too much is used at one time. You should definitely proceed with caution. It’s best to apply blood meal to the soil a little while before planting anything in it. Even so, blood meal’s fast-acting nature makes it a good tonic for ailing plants. You will need to pour this fertilizer over the plants roots according to the package directions and then possibly cover everything up with mulch.
Recommendation: Espoma Dried Blood Meal, 3.5lb
NPK Ratio: 4-20-0
It’s no surprise that bone meal is made from ground-up cow bones. This high phosphorus fertilizer also contains plenty of nitrogen. It works at moderate speeds to encourage flower production and root growth. As a result, it is great plant food for flowering plants, bulbs, and fruit trees. However, it is mostly used as a soil amendment for spots with high nitrogen levels where plants keep getting burned. Still, it’s sometimes a better plant food than those made from synthetic chemicals when applied correctly.
Recommendation: Espoma Organics Bone Meal Fertilizer, 4lb
NPK Ratio: 12-0-0
Feather meal is very high in nitrogen. However, it doesn’t contain any calcium or phosphorus, and it only works at moderate speeds. If you plan on using this fertilizer in your yard, use it prior to planting in order to give the soil a nutrient boost. If you’re wondering whether or not it’s an appropriate time to apply this fertilizer, do a soil test first.
Recommendation: Down To Earth Feather Meal, 5lb
NPK Ratio: 10-10-2
Seabird guano is gathered from islands that have low rainfall and arid climates, both factors which help it retain high levels of nutrients. Seabird guano contains large levels of trace elements along with decent amounts of nitrogen, phosphorus, and calcium. In fact, it is considered to be among the world’s best organic fertilizers, especially beneficial for remedying a nutrient deficiency in a garden.
Recommendation: Down To Earth Organic Seabird Guano, 5lb
NPK Ratio: 7-3-1
Bat guano is a fast-acting fertilizer that contains a wide variety of nutrients such as nitrogen, phosphorus, calcium, and various other minerals. Bat guano is not as high in these components as seabird guano, but it is more readily available to beneficial organisms in garden beds that promote healthy growth. Since some of the nutrients in bat guano are water-soluble, this fertilizer is probably most effective when used in liquid form as a foliar spray or a compost tea, differing from chicken litter. You can also apply it between crop plantings and as a soil refresher in the late spring.
Recommendation: Down To Earth Bat Guano, 2lb
NPK Ratio: 4-12-0
Due to its high nitrogen levels, fish meal is a fairly fast-acting nature fertilizer. It also has decent amounts of phosphorus and calcium. It is good for corn crops, and it uses leftover fish parts. Being ecologically sensitive in organic gardening is just as nature intended!
Recommendation: Down To Earth Fish Bone Meal, 1lb
NPK Ratio: 2-4-0 to 5-1-1
This product is made from partially decomposed fish. As a result, it often has a fishy odor (although the AgroThrive brand smells a bit like soy sauce and is not unpleasant). Fish emulsion fertilizer is high in nitrogen, but it contains little to no calcium or potassium. It is also very acidic and should be used lightly to avoid burning plants. It nonetheless acts immediately once it is applied, making it a good treatment for increasing organic matter in leafy species suffering from low nitrogen levels. However, some plants may not tolerate it very well.
Shellfish Fertilizer / Shell Meal
NPK Ratio: 3-3-0
This fertilizer is made from crushed-up seafood byproducts. It contains plenty of calcium and some phosphorous, as well as a large quantity of trace minerals. Shell meal also contains an element called chitin, which helps ward off pesky nematodes.
Recommendation: GS Plant Foods Crab Shell Fertilizer, 8lbs
Liquid Kelp Fertilizer
NPK Ratio: 1-0.2-2
This is a liquid seaweed fertilizer created by cold processing. Kelp contains small amounts of the main three fertilizer components, but it’s quite high in trace elements. It is also a good source of growth hormones that can help plants reach their full potential by supporting root development. This liquid fertilizer is typically mixed with water and used as a foliar spray or poured into the soil around plants.
Recommendation: Maxicrop Liquid Seaweed, 32oz
NPK Ratio: 1.5-0.75-5
Seaweed is a fast-acting fertilizer that’s often available for free along most coastlines. It contains all of the major three nutrients in small amounts but also contains plenty of zinc and iron. Seaweed is considered highly beneficial to grain crops as well as those that need high levels of potassium.
Recommendation: Down To Earth Kelp Meal, 5lb
NPK Ratio: 1-0-1.2
It’s hard to beat grass clippings as a low-cost fertilizer since they’re usually free. This substance can be used to prevent weeds and conserve moisture in the soil. However, the nitrogen content in each batch varies. A layer of 1 to 2 inches should be sufficient for a full growing season. Just don’t use cuttings from lawns that have been grown using herbicides. Clippings can act as a slow-release substance for plant roots as they decompose. If you want a nitrogen fertilizer, organic and contained within your garden system, this is it.
Recommendation: Free from your yard or your neighbor’s!
NPK Ratio: 0-0-.2
Azomite, among other ground-up rocks, are technically inorganic fertilizers as they come from mineral sources. You can find this ground-up rock dust in a granular form that is slow-release or in faster-acting forms. Azomite is the inorganic fertilizer byproduct of mining in certain ancient volcanic areas of Utah. It provides trace minerals to the soil, rather than acting on the macronutrient content of soil. Most of the time, it is worked into the soil as a conditioner or added to compost.
Recommendation: Down To Earth Azomite, 5lb
NPK Ratio: 46-0-0
Interestingly, this is the byproduct of human urine that comes after the human body breaks down proteins into amino acids. Using urine as fertilizer isn’t uncommon, and plants often benefit from a diluted solution of urea in water. There are plenty of times it’s not the best idea to use it in gardens, though. Try checking out our article on this very topic before springing for urea.
Recommendation: Free as urine!
Frequently Asked Questions
Q: What are 5 examples of organic fertilizer?
A: Cow and chicken composted manure, liquid kelp, alfalfa, and bone meal are all examples.
Q: Which is the best organic fertiliser?
A: It depends on the plant in question and what that plant needs.
Q: What are the four main organic fertilizers?
A: There are only 3. Animal manures, plant wastes, and green manures are the 3 types.
Q: What are organic fertilizers?
A: They’re bioavailable byproducts that come from one the 3 sources above.
Q: What are the 3 types of organic manure?
A: Chicken, cow, and bat guano are 3 types. But there’s also horse manure, seabird guano, humanure, rabbit manure, and others.
Q: Can organic fertilizer burn plants?
A: Sometimes they can. It’s best to use caution when applying them, follow the label, and mix that up with your own judgment concerning what plants need.
Q: Why is organic fertilizer better?
A: It’s better because it won’t wash away in heavy rain or irrigation, it promotes better soil health in the long run compared to synthetics, and it’s more readily available to your plants.