Cannabis Cultivation

Top 10 Organic Growing Amendments for Cannabis

Growing Amendments for Cannabis

It is no secret that we at Green Avenger Seeds love growing cannabis and using organic growing amendments for our breeding. We develop and grow all our marijuana seeds listed on our website using completely organic methods. Growing cannabis using sustainable methods is something we feel very strongly about. We believe that you should as well for the sake of our planet and everyone’s health that lives here.

Growing Cannabis organically is one of the easiest ways to grow. It is very easy to keep your plants healthy and very hard to kill them using organic growing methods. You will never burn your plants like when using salt based nutrients like those used for hydroponics

The goal of growing with organics as opposed to growing other ways is to provide your plants with the nutrients that they need, and not to over feed. You only want to provide enough nutrients that the plant can feed itself using the soil and organic nutrients provided for them.

Important Organic Mineral Elements

When adding organics to your soil, you are using these to feed the bacteria that is breaking down the organic amendments into usable nutrients for your cannabis plants. The plants are then able to absorb these nutrients to help your plants grow healthy.

What is the best way to do this?

Well that answer is easy to conclude here. Feed the soil and the soil bacteria, that will in turn feed your cannabis plants. This sounds very easy, because it is easy to do organically. 

In this article we will detail our top 10 organic growing amendments for growing marijuana organically.  This list will go in order from number 10 down to our most recommended amendment for growing cannabis and why we feel they are our top ten.

Langbeinite - #10 Best Organic Growing Amendment

Langbeinite Organic Amendment For Cannabis

If you can get your hand on some langbeinite then you are in luck. This is an organic mineral and is farmed in Carlsbad, New Mexico from ancient oceans that it was left behind. It is made up of potassium, magnesium and sulfur. These are all very important nutrients for growing healthy cannabis plants. 

This amendment is particularly useful in flowering cannabis plants. This amendment is considered potash, this means that it has a good organic supply of potassium, a very important plant nutrient for growing big cannabis buds.   

Usage: Use about one tablespoon of Langbeinite per gallon of organic soil and mix it in well. You can also use it as a top dressing on top of the soil during the flowering period.

Fish Meal - #9th Best Organic Growing Amendment

Fish Bone Meal Organic Amendment For Cannabis

Next fish meal is a buy produced by the fishing industry. It is the ground up fish that are left over from processing fish for food. Fish meal is awesome for cannabis cultivation for a couple of reasons. First it helps to stimulate microbial populations in your soil, and containers. Fish meal is an excellent organic growing amendment for its high nitrogen, not only that it will release the nitrogen slowly and can last for a few harvest because it will break down so slowly. 

This nitrogen will feed you soil bacteria for months or even years depending on how much you use. This organic growing amendment is also very cost effective as it doesn’t cost as much as some other amendments. 

Usage: 3-4 Tablespoons per gallon of organic soil. You can mix this in well with the soil. This is also an excellent top dressing for your cannabis containers during the vegetative period of growth. Growers can stop adding it as a top dressing once they switch to a 12/12 lighting schedule.

Gypsum - #8th Best Organic Growing Amendment

Gypsum Organic Amendment For Cannabis

Our next organic growing amendment for cannabis is gypsum. Gypsum is mine in many places in the world, and is another great amendment for growing cannabis plants organically. Gypsum is great for increasing sulfur and calcium in your growing soils in a container or in your soil. 

As a soil conditioner its primary form is calcium sulfate (calcium, sulfur), while gypsum shouldn’t be the only form of organic calcium ( we will provide more options below) . It is a great amendment to help you plant grow and help to balance PH in your potted soils for your plants. 

Usage: Gypsum can be used in a few different ways, first you can mix it in water and water it into your cannabis containers or outdoors. You can mix in 3-4 tablespoons per gallon of water and pour over your plants.

Growers can also mix it on with their organic soils before planting. You can use one cup of gypsum per gallon of soil. It can also be added as a top dressing for your pots. Put a small layer of it over top of the container soil. This will get watered in as the plant grows.

Alfalfa Meal - #7th Best Organic Growing Amendment

Alfalfa Meal Organic Amendment For Cannabis

Cannabis growers have been using alfalfa meal for cannabis for decades and for good reason. Alfalfa meal comes from fermented alfalfa plant seeds. It is very light, easy to use and smells like dried fresh grass. Unlike the other organic amendments above, the big plus is that it contains “triacontanol” , which is a growth stimulant present in alfalfa meal when it starts to break down in your soil. This stimulant can increase cannabis flowering yields, and overall growth of the plant.  Once the alfalfa is broken down in the soil it also provides a healthy source of nitrogen to the plants and soil bacteria that will feed on it. 

Usage: Growers can use Alfalfa meal in the soil, you can mix in 5-6 tablespoons of alfalfa meal into each gallon of organic soil. We don’t recommend using it as a top dressing as it will not break down fast enough to have any benefit, in containers. However you can use it as a top dressing outdoors, and will break down over many seasons of cannabis growing. 

We highly recommend it as a tea. You can learn how to make a Alfalfa tea for your cannabis plants either indoors or outdoors here.

Insect Frass- #6th Best Organic Growing Amendment

Insect Frass Organic Amendment For Cannabis

Our next great organic amendment for healthy cannabis growth is Insect frass. This is an all-natural, feces of many different types of insects. The insects eat plants and in turn poop out healthy feces that can be used on your cannabis plants. It is high in nutrient content, and is great for flowering cannabis. It also contains an interesting natural biopesticide called Chitin. 

If you have any issues with root eating pests, Insect frass is excellent to have in your soil. Chitin can naturally kill root-feeding nematodes and their eggs. It is great if you have had fungus gnat issues in the past. It is an awesome way to kill root pests in your cannabis containers, and a valuable food for your plants and soil bacteria. 

Usage: You can add one cup per gallon of organic cannabis soil, then mix it in well. You can also use it throughout the plant’s growth, as a top dressing. It will help to keep those pesky fungus gnat as bay, and keep them from getting into your soils. It also works great when added to organic teas.

Kelp Meal - #5th Best Organic Growing Amendment

Kelp Meal Organic Amendment For Cannabis

This is a great organic amendment for cannabis plants with over 70 plant vitamins and minerals to grow huge cannabis buds. Kelp meal is made up of seaweed that grows in the ocean and is harvested and refined to a liquid for plant or ground up as a powder, or meal form. Although kelp is not very high in major nutrients for your cannabis plants it benefits are many. 

It adds many micronutrients, growth hormones and vitamins. All this helps improve potting soil and it’s most important it helps the plant when dealing with stress. This stress can be in the form of pests, lack of water, and diseases like mold. We think that any organic cannabis grower should be using kelp meal.

Another really cool form of kelp comes in soluble seaweed. This is in a ground form and when it is added to water it will dissolve into the water. 

Usage: Kelp meal can be used in many different ways, all of them beneficial for your plants. First you can use the ground up meal as an amendment that can be mixed with your organic soil. Kelp meal can also be used to make organic teas for cannabis. Growing can use liquid kelp as a foliar feed, it can be mixed with water and then sprayed on the plants, the leaves will absorb the kelp and create a very healthy plant. 

It can also be used when mixed with water and poured onto the soil for the roots of the plant to take in. You can mix 3 tablespoons of Liquid Kelp into one gallon of water, then use this as a soil drench.

Rock Dust - #4th Best Organic Growing Amendment

Rock Dust Organic Amendment For Cannabis

Rock Dust is exactly as it sounds, ground up rocks into a fine powder. However don’t be fooled, it is a very powerful amendment for soil and growing great cannabis. Rock Dust when added to soil has been proven to improve soil PH, water retention in cannabis containers, diversify microbial soil activity, can increase plant health overall and has tons of micronutrients for growing cannabis.

In it your plant will find large amounts of silicon (very important to plant health), aluminum and some iron.   

Usage: Rock Dust works best when it is mixed in with your organic soil before planting. You can add a quarter cup of rock dust, for every gallon of soil. It can be used for indoor cannabis containers, or outdoors mixed in with your soil.

Rock Phosphate - #3rd Best Organic Growing Amendment

Rock Phosphate

Another rock type organic fertilizer, this is a great amendment to use for flowering cannabis plants. This amendment is mine from clay deposits that contain high amounts of phosphorus. As we know phosphorus is a great nutrient to help cannabis plants flower and grow large dense buds. This amendment also can help create much better favors and terpenes on your growing cannabis buds. If you use this organic amendment in your soil you will notice a big boost in flower smell and sweet taste of your buds.

Usage: Can be used in organic cannabis teas, mixed into soil before planting at 1 cup per gallon of soil, it works great as a top dressing for your growing containers, just take a couple of handfuls about one week before you switch 12 hours of darkness to flower your cannabis plants. Growers can also add it around their plants outdoors as the hours of daylight start to turn.

Oyster Shell Flour - #2th Best Organic Growing Amendment

Oyster Shell Flour

We can’t say enough good things about oyster shell flour for your growing plants. Calcium is one of the most important nutrients for your plants. Oyster shell flour will give you plants all they need throughout their growing seasons. It is made up of ground oyster shells, and in the form of a flour type substance. It is great for the bacteria living in your soil, and will really help them grow and thrive in your soil. This is awesome because we know that the more bacteria and fungus you have living in the soil the more they will break down nutrients for your cannabis plants. 

Usage: Oyster Shell Flour cannabis be added to water and watered into the soil of your growing plants. You can use about 1 tablespoon of oyster shell flour per gallon of water. It can also be used when mixed into your soil before planting. Use about a half a cup per gallon of soil.

Worm Castings - #1th Best Organic Growing Amendment

So where does all this bacteria and micro life come from? Well from our number one best organic growing amendment for cannabis. Worm Castings whether you farm them yourself or buy them at the gardening store are a perfect organic fertilizer for cannabis plants. Worm Castings are the poo from worms, they eat and break down food and their casting are very high in nutrients, healthy bacteria and fungus. 

Once the castings are added to the soil they create an amazing environment for your growing plants. This is our best amendment for organic cannabis growing. 

Usage: Worm Castings will not burn your plants no matter how much you use them. You could grow directly in worm castings and your plants would thrive. However it is best to use them mixed in at about one quarter worm castings for every part of organic soil. They also work well as a top dressing for your plants, or mixed in soil outdoors.

Can You Mix all these into the Soil at one time?

Yes, this is very much recommended. Adding many different organic cannabis growing amendments will help the plant get all the nutrients that it needs to thrive. All these amendments will break down over time, and at different rates. This will provide nutrition for the growing plants, and they can use them as they need over the cultivation period.


Growing Cannabis organically is not only healthy for the planet, but much healthier for the grower. Keep the planet safe and healthy and keep growing organic cannabis!

Related Posts

Leave a Reply

Your email address will not be published. Required fields are marked *