15 Organic Soil Amendments For Organic Gardening You Must Use To Boost Your Vegetables

Every good gardener on this planet knows (or should know) how important are additives for the soil. Since organic gardening is luckily in full swing, more and more people are turning to this way of growing vegetables. As one of those, I have decided to give you a list of most commonly used organic amendments with explanations what for are they good.

Thus, these 15 organic soil amendments for organic gardening are at your disposal. Feel free to use it either as a guide or as a checklist in case that you missed something.

15 Organic Soil Amendments For Organic Gardening


What Is Organic Gardening In The First Place?

Organic Gardening

In a few words, organic gardening means the absolute absence of any chemistry and similar solutions. For the process to be called such, it is vital that everything included can be called “natural.” Of course, many people will think that “organic” includes only organic matter from our surrounding, but it is not like that. Limestone, for example, is an inorganic matter, but since it is not artificially made, its appliance is still considered organic.

On the other hand, there are a lot of solutions on the market which are offering “organic additives.” It is enough for the coloring to be non-organic, and that all of your efforts will be thwarted. Therefore, rely on those things you can call natural and entirely organic. Here they are.

1. Alfalfa Meal

Alfalfa Meal

As the name suggests, this addition is made from the alfalfa plant. It grows on nearly every continent in the world, and most commonly is used as food for domestic animals. Its main advantage is that it is rich in nitrogen. This is the main reason why it is used.

Its NPK value is usually 5:1:2, and therefore is primarily intended for plants which require a higher amount of nitrogen, while still not being strong fertilizer. It also contains triacontanol, which is known to promote plant growth, especially of roses. It can be used in the form of meal, pellets or even tea can be made. Also, hay can be applied, since it works both as mulch and as a fertilizer.

For which plants it can be used?

Nitrogen-hungry ones such as beets, broccoli, cabbage, spinach, potato.

2. Azomite


Although it sounds like a chemical ingredient, Azomite is, in fact, a rock. It is mined in Utah, USA, and its primary purpose is to increase the level of minerals in the soil. Moreover, it is useful as an anticaking and anti-lumping agent.

Since the area where is Utah today was once sea bottom, this mineral is highly rich in a wide array of minerals as well as components from volcanic ash which is also known to be highly rich in useful substances. This addition is best used for gardens which have fed heavy feeders such as beans or cabbage. Also, it is vital to use it once in every three months, best diluted in water, to resupply minerals in the soil. 

For which plants it can be used?

Nearly every plant benefits from this additive; it boosts overall plant growth and health.

3. Blood Meal

Blood Meal

Although this additive sounds like something a witch would use, it is quite beneficial for plants. Blood meal, as the name suggests is made of dried blood as a by-product of the meat industry. When blood is dried, and ground, all which remains after are proteins and nitrogen in most significant percentage. This is convenient and useful for gardeners.

Since it is high in nitrogen (13:1:0), blood meal is used for nitrogen-demanding plants, and since its secondary feature is to repel rabbits, it is one of the best fertilizers used for cabbage. Also, it is of slow-release type, so prolonged period of fertilization is assured.

For which plants it can be used?

Primarily cabbage and others which require high nitrogen level

4. Bone Meal

Bone Meal

Another witchcraft ingredient, bone meal is also a by-product of the meat industry and is made from dried and ground animal bones (of course). It contains a high amount of calcium (20-25%) as well as 20% of phosphate. These numbers can vary, however, depending on the manufacturer.

How fast and how long bone meal will release its nutrients depends on how finely it is ground. The more fine the dust is, the quicker it releases, but its releasing time is shorter. It is primarily used as a source of phosphorus, and as such benefits the most to legumes and cabbage families after the head develops.

For which plants it can be used?

Cabbage family, after forming the head and legumes

5. Chicken Manure

Chicken Manure

For those who have chicken in their backyard, there was at least one opportunity when you took manure left from them and used it as fertilizer. This is an excellent cycle since something considered as residue is used with great purpose.

The main advantage of this manure is that it is rich in nitrogen (3:2:2), the highest of all animal manures. It is also suitable for retaining moist in the soil, so working in a few inches and followed by six to nine months of occasional turning will make the ground fertile, loamy and rich.

For which plants it can be used?

On nearly every plant, it is well balanced, and all plants benefit from it

6. Coconut Coir

Coconut Coir

Let me get in my tropical shirt since this additive comes from remote beaches and coconut palms. Since you know how coconut looks like, you have noticed that there are fibers on the outer side of the shell. Those threads are collected, and a great alternative to peat moss is thus made.

This coir is so good that it can be considered as a complete replacement for soil, but since the cost of such approach can be astronomical, it is usually worked into the ground, to retain water. Its retaining abilities are surprising since it can hold water ten times its weight, so it is great for plants which need water during hot summer months. On the other side, however, coconut coir doesn’t contain nutrients, so it won’t help to promote the growth, but won’t make a misbalance either.

For which plants it can be used?

Water-demanding plants, such as tomatoes and peppers will benefit the most from this ingredient

7. Compost


Now we’re getting to “completely natural” item on my list. Compost is an alpha and omega of every garden. Quite literally, in fact. It is made from biowaste and residue which is usually thrown away. The best way to make compost is to get one of those compost tumblers and start cooking (this is just an expression, you don’t need to cook anything on the stove).

Since rotting plants, grass cuts and other waste is put into a tumbler, it is left to rot with occasional turning. The main idea is to let beneficial bacteria decompose residue into elements which can be then absorbed by plants. Compost is used to decrease the percentage of clay in the ground, and to help water drain faster, with better moist retention. As for nutrients, it can contain everything, from minerals, proteins, salts to three basic ones (NPK – Nitrogen, Phosphorus, and Potassium) literally.

For which plants it can be used?

Every plant benefits from compost; can be applied everywhere

8. Greensand


As the name suggests, it is sand, and it is green. Its primary purpose is to reduce lumpiness in the soil and to help you amend heavy, clay-rich grounds. It gained popularity just recently since it is considered as the best kind of sand to work into the soil.

The green color of this sand comes from its origin. Mostly found in areas where sea used to be, greensand is rich in minerals and ingredients which ordinary sand doesn’t have. The standard type of sand is effective in reducing clay in the ground, but this one also improves drainage of the soil with the addition of minerals at the same time.

For which plants it can be used?

Those who require good drainage, such as onions will benefit from greensand the most

9. Gypsum


Although the name might seem a bit strange, if I say “plaster,” you will know what I’m talking about. To be honest, I didn’t realize that gypsum can be used in the garden since when mixed with water it can get lumpy, clay-like and will hard in time. I also didn’t know that it is rich in calcium and sulfur, which reduces pH value of the soil.

Highly alkaline soils are thus a primary target for the appliance of the gypsum. It will also increase the level of calcium in the ground, which benefits the plants.

For which plants it can be used?

Those who need acidic or pH-neutral soils, such as cucumbers, squashes, and carrots

10. Kelp Meal

Kelp Meal

Another meal for plants, this one brings the whim of the sea wherever it goes. Although any salt is removed from this additive, it still bears useful elements found in seawater only. Kelp meal, as the name suggests is made of seaweed which is collected, dried and then ground to dust.

Since it is rich in nutrients and remains plant-based, it is very convenient for those gardeners who wish to have a completely vegan approach to their production. Also, it is rich in potassium, which will help the plants to be more resistant to pests and diseases. Its NPK index can vary, depending on the manufacturer.

For which plants it can be used?

Those who need mild fertilizers, such as tomatoes

11. Dolomite Lime

Dolomite Lime

The opposite of greensand and sulfur, dolomite lime increases pH factor in the soil, thus reducing acidity, while increasing alkalinity. This is often called “sweetening of the soil.” It also packs great reserves of calcium and magnesium.

Therefore, if your testing kit tells you that level of magnesium is dropping, and acidity is rising, it is probably the right time to spread some of this wonder-making dust.

For which plants it can be used?

All plants require magnesium, so if you have acidic soil and want to amend this, dolomite lime is probably the best way to do so

12. Rockdust


Have you ever wonder what an ordinary rock is made of? Let me answer you in one word: minerals. This is the primary purpose of this additive, to bring back spent minerals which plants have used and left the empty ground behind.

Of course, you won’t wander around through the garden and throw rocks at your plants, since manufacturer grinds the stones into fine dust so that it can be either spread by hand or diluted in water and distributed in that way. Since it doesn’t have NPK nutrients, it is suitable for almost every garden.

For which plants it can be used?

Every garden benefits from this amendment, but be careful; it will influence the pH value

13. Rock Phosphate

Rock Phosphate

Again, nomen est omen, the Ancient Romans would say, since this additive is almost pure phosphorus in rock shape. It has very long working time, and it can provide your ground with reserves of phosphorus for a decade!

Although this is usually an advantage, it requires careful planning. Not all plants need too much phosphorus, and if you are uncertain about years to come, feel free to cover only one part of the garden with this ingredient, and plant flowers for example. They will develop great roots and seeds from this element.

For which plants it can be used?

Primarily flowers, but onions will need it to develop bulbs properly

14. Bat Guano

Bat Guano

In case that you didn’t know, “guano” is a fancy name for feces of birds and bats. This list would be too dull without several extravagant items, wouldn’t it? Now, as for nutrients, bat guano is usually produced in 10:10:2 variety, and it works fast. Its working time is short, so it is ideal for a quick shot of nutrients.

It is also water-soluble, so making a compost tea is probably the best way to apply it. 

For which plants it can be used?

Considered as standard fertilizer, can be used for garlic

15. Worm Castings

Worm Casting

Every once in a while, I hear advice “throw in some worm castings.” Everyone is using them, but are they that good? Probably not, they are even better!

If you don’t want to bother with compost tumbler, find a few Californian worms, give them some manure, and let them do their magic. By eating through the soil and compost, they will aerate it, with only traces of nutrients remaining (2:1:1). Since these are deficient numbers, worm castings can be used everywhere; burns from too much fertilizer is almost impossible.

For which plants it can be used?



So, here they are. 15 organic soil amendments for organic gardening are at your disposal. Feel free to use them in your garden, no matter if you follow the natural gardening path or not.

Also, if you have any advice, opinion or question, feel free to drop it in the comment section below.

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