16 Best Organic Fertilizers & How To Use Them In the Garden

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Organic fertlizer

Whether you already are an organic gardener or you just get started with organic gardening, there are many important questions you may ask.

What kind of organic fertilizer should you use on your plants? In what concentration? Does organic really make a difference? Keep reading to find out!

Here is a quick navigation table you may find handy.

Types of Organic Fertilizers

1. Cow Manure

Cow Manure

Credit to chesbayprogram

Typical ratio of 3-2-1

Manure tends to have a low nutrients ratio compared with its mass. However, it works fairly well as an organic fertilizer and may be readily available and cheap to buy from local farms. It is generally recommended to use manure as an addition to your compost. Composted manure produces a third fewer greenhouse gasses than fresh manure, making it better for the environment. Composting the manure also eliminates the ammonia content, which can be harmful to plants and burn the roots. It is possible for weed seeds to survive a cow’s digestion process, which could then cause weeds to spring up among your plants if you add fresh manure to the soil. However, weed seeds won’t survive the composting process, which is another reason to compost manure to make your organic fertilizer.

2. Chicken/Poultry Manure

Chicken/Poultry Manure

Typical ratio of 4-2-1

Chicken manure is one of the most commonly available organic fertilizers on the market. It is usually sold in the form of dried pellets or powders. If you have access to fresh chicken manure, this would be put to better use in your composter. Chicken manure is a good source of nitrogen, which supports a plant’s foliage growth, but other nutrients in chicken manure are minimal, so you might want to supplement chicken manure with other fertilizers that are higher in the other nutrients. Chicken manure releases its nutrients slowly and gradually and needs a good stretch of warm weather to do so. Chicken manure is not recommended for acid-loving plants.

3. Compost


Typical ratio of 2-1-2

The nutrient ratio of compost can vary significantly depending on what materials have been composted, but typically, it contains a fair level of all three main nutrients. Compost is popular among gardeners, probably because it is free to make at home, requires little effort, reduces home waste, and is versatile to use. It can be mixed with soil to improve soil quality before planting, as a top dressing or mulch, as a soil refresher between growing seasons, or brewed to a compost tea, which can be used as nutrient-rich water for plants, or as a foliar spray. Composting is a fairly straightforward hobby to get into once you understand the key principles and takes up very little space and time. If you are keen to move from a synthetic fertilizer to an organic fertilizer but are put off by cost, then composting might be a good solution.

4. Grass Cuttings

Grass Cuttings

Credit to cropshot

Typical ratio of 1-0-1

If you’re keen on living a thrifty and sustainable lifestyle, grass cuttings are one of the best easy organic fertilizers out there. Simply use your own grass cuttings from when you mow your lawn or ask your neighbors if they’d mind letting you have theirs; most people would be happy to donate their grass cuttings as it saves them having to get rid of it themselves! With a low ratio of nitrogen and potassium, grass cuttings aren’t the most nutritious fertilizer, but they will help your soil quality and plant growth over time, and it also possesses other beneficial qualities. A two-inch layer of grass cuttings over the top of your soil will help to prevent weeds sprouting through, and it will also act as a mulch to help the soil retain moisture.

5. Cottonseed Meal

Typical ratio of 6-1-1

This organic fertilizer is high in nitrogen, with reasonable amounts of phosphorus and potassium, making it well-suited to plants where you want to see lots of new leafy growth. Apply it to the soil in the fall and add mulch over the top, as this will give the cottonseed meal enough time for nutrients to be released, ready for planting time in the spring. The main drawback of cottonseed meal is that it can be hard to source unless you live in an area that grows cotton crops.

6. Blood Meal

Typical ratio of 12-1-1

This fertilizer is definitely not one for vegetarians or vegans as it is made from the blood of slaughtered animals. It gets dried out and then ground into a powder, and although it may make some people uncomfortable, it could be seen as a good way to make sure all parts of the animal are used without any going to waste. Blood meal is very high in nitrogen with a fair amount of other nutrients, so it’s another good fertilizer to use to encourage leafy growth. It is faster acting than most organic fertilizers, so it works well on plants that are struggling and need immediate help. The drawback is that it is very acidic and can burn plants if it is overused.

7. Soybean Meal

Typical ratio of 7-2-0

Simply made of ground or crushed soybean, this organic fertilizer is high in nitrogen with fair amounts of calcium and phosphorus, though it has no potassium content. The release of nutrients will depend on soil conditions, but in general, the nutrients will work their way into the soil at a moderate speed.

8. Feather Meal

Typical ratio of 12-0-0

This is another fertilizer that animal lovers might want to avoid. It is made from feathers that are a byproduct of the poultry industry. The feathers are heated to a high level, ground to a powder, and dried out. This fertilizer contains high levels of nitrogen but no other nutrients. It may work well in combination with other fertilizers or could be mixed into the soil before planting to improve soil quality.

9. Bone Meal

Bone Meal

Credit to phuthinhco

Typical ratio of 4-20-0

This is a fertilizer made from the ground-up bones of dead cows. It might make some people squeamish, but many see it as a useful way to minimize the waste associated with the beef industry. The fertilizer is very high in phosphorus, which is important for flower production, along with a good amount of nitrogen. This fertilizer would be best utilized on bulbs, flowering plants or trees, and fruit-bearing plants.

10. Fish Meal

Fish Meal

Credit to phuthinhco

Typical ratio of 5-2-2

With a good level of nitrogen and fair levels of phosphorus, potassium, and calcium, this is a good all-around fertilizer for a range of plants, shrubs, and trees. All parts of a fish are used to produce fish meal, including bones, skin, and scales, utilizing parts of fish which would otherwise be wasted. Fish have long been used to fertilize plants; centuries ago, Native Americans would dig a hole and place a dead fish in it before planting a seed on top. As the fish decomposed, it would release nutrients that would aid in the growth of the crop.

11. Shell Meal

Typical ratio of 5-2-5

Made of ground or crushed seafood byproducts, this sustainable fertilizer is high in both nitrogen and potassium with a fair level of phosphorus, as well as calcium and a good amount of trace minerals, making it a good all-around fertilizer for most plants or trees. Shell meal also helps to discourage pesky nematodes from inhabiting your plants, thanks to a naturally occurring element in shellfish called chitin.

12. Corn Gluten Meal

Corn Gluten Meal

Credit to phuthinhco

Typical ratio of 0.5-0.5-1

Corn gluten meal has low nitrogen, phosphorus, and potassium content but works well to stabilize soil over time if it is used regularly. It should be applied to soil in the fall so that it has enough time over winter to positively impact the soil by the time spring rolls around. There is also some discussion that corn gluten meal works as organic weed prevention. It is claimed that it prevents seeds from germinating, resulting in no weed growth in plant beds or lawns. Therefore, it might be worthwhile to spread this fertilizer on lawns as well as on soil.

13. Seaweed


Credit to cucchiaio

Typical ratio of 1-1-5

With a good amount of potassium and trace amounts of nitrogen and phosphorus, as well as magnesium, iron, copper, boron, and zinc, seaweed makes an excellent plant fertilizer that you could forage for free if you live near the coast. It can be bought in the processed form of dried, ground, or liquid, which can then be added directly to the soil. However, if you are able to get your hands on fresh seaweed, then you can dig it right into your soil. As seaweed is rich in trace elements that plants only need a little of, it is often added to both organic and synthetic fertilizers. It has gained popularity among gardeners because it contains lots of nutrients that many other organic fertilizers lack.

14. Bat Guano

Bat Guano

Credit to berniedup

Typical ratio of 10-10-2

Bat guano is the manure or dung of bats. Being high in both nitrogen and phosphorus, with a low amount of potassium, it works well as a fertilizer for both leafy and flowering plants. It is also rich in a selection of micronutrients, though the composition of nutrients can vary depending on the diet of the bat. Bats that primarily eat insects will have dung with a higher nitrogen ratio, while bats that eat fruits will produce guano with a higher phosphorus ratio. Bat guano is relatively fast-acting compared to most organic fertilizers, and it has other benefits besides being a good fertilizer. It is said that both fruits and vegetables which have been grown in soil where bat guano has been utilized, will be resistant to disease, and more flavorful. The nutrients of bat guano are water-soluble, so while it can be added directly to the soil, it can also be brewed into a tea and used as a foliar spray or to give your plants a nutritious watering.

15. Seabird Guano

Typical ratio of 10-10-2

Seabird guano has similar NPK ratios to bat guano, but it is higher in trace nutrients and minerals. It is believed to be one of the best fertilizers in the world, but, unfortunately, it is not very easy to source due to the nature of its origin. Seabird guano is collected mostly from islands off the coast of Peru where the climate is ideal for producing nutritious bird excrement. Strict rules are in place to ensure that no bird settlements are disturbed in the collection process. The result of this is that seabird guano is something of a treasure, and can, therefore, demand a high price.

16. Worm Casting

Worm Casting

Credit to pfly

Typical ratio of 1-0-0

Worm Casting is one of the most popular organic fertilizers that is known to greatly aerate, enrich the soil, improve its structure, and hence add useful nutrients to plants. Typically containing a nearly balanced ratio of N P K, worm casting works great to improve the soil, growing container plants, houseplants, or is used for compost bins, etc.

Using Fertilizer

Fertilizers were created to balance out the nutrient levels in soil, making for healthier plants and allowing plants to thrive even in areas where soil quality is poor. To grow successfully, plants need a variety of nutrients, so if your plants are struggling in spite of you carefully tending to them, then it could be that you have a nutrient imbalance in your soil.

The use of fertilizer will remedy a nutrient imbalance if your soil quality is poor, giving your plants the nutrient boost they need to survive. Even in areas that are fortunate to have naturally rich and fertile soil, the plants you are growing will absorb all of the nutrients from the soil over time, and you will need to replace those used up nutrients with fresh nutrients. Fertilizer is an ideal way to do this, ensuring your plants have access to the nutrients they need to survive.

Some plants, particularly flowering plants, have very high needs when it comes to nutrients, and in order to continue to produce an abundance of blooms all summer long, you will continually need to supply them with fresh nutrients. Even where soil quality is good, some flowering plants, such as hibiscus trees, will need to be topped up with fertilizer weekly throughout summer if you want them to produce plentiful blooms. Another advantage of using fertilizer is that your plants will grow bigger and stronger than without it. Fertilizer is seen by some as a miracle food for plants, allowing them to grow more quickly and, in some cases. even double in size.

Fertilizers are based around the three essential nutrients that plants need: nitrogen, phosphorus, and potassium. The ratios of nutrients are always listed in the order of N-P-K, the letters denoting the chemical symbols of the nutrients (N for nitrogen, P for phosphorus, and K for potassium). For example, if fertilizer is described as having a ratio of 5-3-2, it means it has 5% nitrogen, 3% phosphorus, and 2% potassium.

What is Organic Fertilizer?

a shovel full of cow manure organic fertilizer

The term “organic fertilizer” refers to any fertilizer that is made from naturally occurring nutrients that have not been highly processed. It does not mean “organic” in the sense that many of us have become familiar with, in particular in regard to organic food, and instead simply means that it is not man-made.

Organic fertilizer could be a byproduct of another industry, such as cow manure. However, the term “organic” does not mean that the cows have been fed an organic diet, or in the case of compost as an organic fertilizer, it does not mean that the compost has only been produced from organic vegetable scraps or garden waste free from chemical pesticides or insecticides.

Synthetic fertilizer is the opposite of organic fertilizer and is also known as chemical fertilizer or artificial fertilizer. It is made from non-renewable sources, such as fossil fuels, and goes through a highly processed journey to reach the state that we can buy it in.

Organic Fertilizer Advantages

Both organic and synthetic fertilizers will do the job of improving your plants’ health and helping them to grow successfully, so it can be hard to determine which type of fertilizer you want to use. Many gardeners have their own preferred way of fertilizing plants, but it can be helpful to fully understand the advantages and disadvantages of organic versus synthetic fertilizer. Though your plants won’t know the difference between the two, there are some key elements that distinguish these types of fertilizer. Understanding this will help you to choose the right fertilizer for you.

Contains Less Salt

Organic fertilizers obtain significantly lower levels of salt than their synthetic counterparts. Salt will increase the acidity of your soil and result in beneficial earthworms choosing to live elsewhere.

Improves Soil Quality

Organic fertilizers improve the quality of soil over time by changing the structure of it. You will find that gardens using organic fertilizer not only have stronger and healthier plants but also stronger and healthier soil. Organic fertilizer also improves the quality of the soil by increasing its ability to retain water. Meanwhile, synthetic fertilizer does nothing to benefit the soil and, in fact, can degrade soil over time.

Is Environmentally Friendly

Organic fertilizers are environmentally friendly because they involve minimal or no processing and are made from renewable sources. They are biodegradable and sustainable, often being made from byproducts of natural things that would ordinarily go to waste. By comparison, synthetic fertilizers are highly processed and are typically made from non-renewable sources, including fossil fuel.

Improves Soil Aeration

Organic fertilizers are lightweight and will make your soil have a lighter texture. This increases aeration and allows more air to reach the roots of the plants.

Ensures No Nutrient Waste

Organic fertilizers break down slowly, with all of the nutrient content being absorbed by the plant. Synthetic fertilizers can get washed out from watering or rainfall, and the nutrients you wanted to supply to your plants can end up in unintended places.

Are Gentler on Plants

The nutrient content of organic fertilizers is typically lower than synthetic fertilizers. This means there is very little chance of causing fertilizer burn damage to your plants, which is common with synthetic fertilizers. The likelihood of over fertilizing your plants with organic fertilizer is very low.

Does Not Cause Chemical Buildup

Organic fertilizers are free from chemicals, and therefore, your soil will not experience any chemical buildup, which can happen with synthetic fertilizers. Chemical buildup in soil can be harmful and even deadly to sensitive plants.

You Can Make it at Home

Many store-bought organic fertilizers are more expensive than synthetic fertilizers, and this is the primary reason that many gardeners turn to synthetic fertilizers: to save on cost. However, it is entirely feasible to make your own organic fertilizer at home completely free. Compost can be easily made at home by simply utilizing kitchen and garden waste. Other organic fertilizers include grass cuttings or animal manure, which you could get for free or for a small cost from neighbors or local farms.

Has No Negative Effect on Ecosystems

One key negative side effect of synthetic fertilizer is that it drains away from the area you used it and ends up in waterways where it is harmful to wildlife. It also has a detrimental effect on beneficial bugs and other small creatures in your garden. By comparison, organic fertilizer presents no risk at all to ecosystems.

Organic Fertilizer Disadvantages

Cannot Achieve Precise Nutrient Ratios

When using organic fertilizer, especially if you have made your own, you can never be certain of the precise nutrient ratio. Organic fertilizers are not produced using an exact science in the same way synthetic fertilizers are manufactured, and therefore, it is something of a guessing game when it comes to specific nutrient content. Nutrient levels can vary depending on the source of organic fertilizers; however, due to their comparatively lower nutrient levels, you will be unlikely to cause any damage to your plants, even if the nutrient ratios are way off.

They Can be Expensive

Organic fertilizers are typically more costly to buy than synthetic fertilizers. If your budget is holding you back from using organic fertilizers, the only way to combat this is to make your own or try to source a local form of organic fertilizer, like grass cuttings or cow manure.

They’re Slow-Release

Organic fertilizers release their nutrients into the soil gradually. This will be a drawback if you have plants that are in decline and struggling to survive. Organic fertilizers will not give your plants an immediate boost in the way that synthetic fertilizers can.

They Require Warmth

In order to breakdown organic fertilizer and release nutrients, microorganisms are required. These organisms need warmth and moisture to work effectively, so organic fertilizer can really only be used properly in warmer months.


I hope this in-depth article about organic fertilizer has given you some light about types of organic fertilizers, their advantages/downsides, and how to use them. Leave a reply below if you have any question. Thank you!

16 Best Organic Fertilizers & How To Use Them In the Garden

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