Organic Nutrients for Cannabis

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What organic nutrients to use for Cannabis ? What are the recipes?

Hi there and Welcome (back) to Free the Tree!

In today’s article we’re going to look at all the different types of organic nutrients available for cannabis.
We’ve been brought up to think that we need to add 3 nutrients. Nitrogen, Potassium and Phosphorus (NPK), added to the soil through chemical solutions to grow nice plants.
But really, organic nutrients will give much larger yields, preserve your ground and cost much, much less. It can even be free if you grow/make it yourself.

Here’s what we’re going to cover:

Organic nutrients for Cannabis - Table of content

Alfalfa Meal

Alfalfa meal has 2.5% nitrogen, 5% phosphorus and about 2% potash. This makes it a very good ingredient for a nutritive solution to be mixed to your watering.
Another way to make the nutrients available to the plant is to let the Alfalfa decompose in the soil. Using this method it will take some time before the nutrients are available.

How to make an Alfalfa based nutritive solution

  1. Place 1 serving of Alfalfa in 10 servings of water.
  2. Cover and let it sit for about 10 days. Stir every day or two.
  3. Extract the liquid
  4. Water your plants with it, all the nutrients will be quickly available to the cannabis’s roots 🙂

Blood and Bone Meal

Blood and bone meals are wonderful organic fertilizers. You must be aware that it could still transport Mad Cow Disease and other sicknesses.
Although full of nutrients we don’t really recommend the use of this.

Blood (dried or meal)

Blood, whether dried or in a “meal” is collected at slaughterhouses, dried and grounded into a powder or meal. It’s packed with fast-acting soluble nitrogen (12 to 15% by weight), about 1.2% phosphorus and under 1% potash.

Apply carefully because it’s easy to burn foliage. Same as Blood and Bone meal we don’t really recommend the use since it could carry diseases.

Blood meal

Blood meal is rich in phosphorus and nitrogen. The age and type of bone determine the nutrient content of this pulverized slaughterhouse product.
Older bones have higher phosphorus content as younger ones. Generally a mix of blood meal and organic nutrients is optimal.

Again, we don’t recommend the use of blood meal.

Cottonseed meal

Cottonseed meal is the leftover by-product of oil extraction. According to the manufacturer, virtually all chemical residues from commercial cotton production are dissolved in the oil.

This acidic fertilizer contains about 7% Nitrogen, 5.5% Phosphorus and 1.5% potash. It should be combined with other nutrients in order to increase nutrient levels.

Chicken Manure

Chicken manure is rich in available Nitrogen, Phosphorus, Potassium and trace elements.
Indoor growers most often prefer to purchase dry, composted chicken manure in a bag. Use it as a topdressing or mix it with the soil before planting.

Nutrient content of wet chicken manure

  • 1.5% Nitrogen
  • 1.5% Phosphorus
  • 0.5% Potassium

Nutrient content of dry chicken manure

  • 4% Nitrogen
  • 4% Phosphorus
  • 1.5% Potassium

Often, chicken manure collected from farms is packed with feathers. Feathers can contain as much as 17% Nitrogen, it’s an nice added bonus.

Both also have a full range of trace and secondary nutrients.

Coffee Grounds

Coffee Grounds are acidic and encourage acetic bacteria in the soil. Drip-coffee grounds are the richest and contain about 2% nitrogen and traces of other nutrients.
Add this to the compost pile or scatter and cultivate them. Use coffee grounds as topdressing, but in moderation since it’s very acidic.

Compost tea

Compost tea is used by mean organic gardeners as the only source of fertilize. Comfrey is packed with nutrient, many gardeners grow it just in order to make compost out of it.

Cow Manure

Cow Manure is sold as steer manure, but is often collected from dairy herds. It’s been used for centuries by farmers which has led to the belief that it is a good fertilizer as well as a soil amendment.
Steer manure is most valuable as mulch and a soil amendment. It holds water well and maintains fertility for a long time. The nutrients value is low, and it should not be relied upon for the main source of Nitrogen.

Nutrient levels of Cow Manure

These are the average levels, they may differ depending on where yo get you manure from.

  • 0.6% of Nitrogen
  • 0.3% Phosphorus
  • 0.3% Potassium
  • Full range of trace elements.

Apply cow manure at the rate of 25 to 30 pounds per square yard.

Colloid Phosphate

Colloid Phosphate, powdered or soft, is a natural clay phosphate deposit. It contains just over 20% phosphorus, calcium and many trace elements.
That said, it’s a slow releasing element, during the first few months it’ll only yield about 2% of its weight.

Diatomaceous Earth

Diatomaceous earth is the fossilized skeletal remains of fresh and saltwater diatoms. It contains a full range of trace elements and is also a very good insecticide.
Apply it to the soil when cultivating or as a topdressing.

Beware: Diatomaceous will cut small insects without discrimination, be very careful on how and where you apply it.
For having tried it ourselves, the benefits aren’t nearly good enough to make it worth it

Dolomite Lime

Dolomite lime adjusts and balances the pH and makes phosphates more available. Generally applied to sweeten or de-acidify the soil.It’s mainly made of calcium and magnesium.

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Feathers and feather meal

Feathers and feather meal contain from 12 to 15% nitrogen that is released slowly. Feathers an excellent addition to the compost pile or as a fertilize.
Feathers are steamed under pressure, dried and ground into a powdery feather meal. Feather meal contains slow-release Nitrogen of about 12.5%

Fish Meal

Fish Meal is made from dried fish ground into a meal. It is rich in Nitrogen (~8%) and contains around 7% phosphoric acid and many trace elements. It has an unpleasant odor, causing it to be avoided by indoor growers, it’s a great compost activator.
Apply it to the soil as a fast-acting topdressing. To help control odor, cultivate it into the soil or cover it with mulch after applying.

Always store it in an airtight container so it doesn’t attract unwanted animals (cats, dogs, flies).
Fish emulsion and Fish meal can contain up to 10% Nitrogen, although the liquid version generally contain less than the meal.

Fish meal, even when deodorized, has a strong unpleasant smell.

Goat Manure

Goat manure is much like horse manure but more potent. Compost this manure and treat it as you would horst manure.

Check out all our articles on organic growing

Granite dust or granite stone meal

Granite contains up to 5% potash and several trace elements. Releasing nutrients slowly over several years, granite dust is an inexpensive source of potash and does not affect soil pH.

Be aware that Granite is very, very slow acting.

Greensand (aka glaucomite)

Greensand is an iron-potassium silicate that gives the minerals that contain it a green tint. In the US, it is mined from the ancient New Jersey-seabed deposits of shells and organic materials.
Greensand is rich in iron, phosphorus and potash as well as numerous micro-nutrients. Glaucomite is a slow acting nutrient.

That said, as it’s a ancient deposits, Greensand is a very limited ressource.
If you’re trying to find ecologically responsible ways to nurture your soil, this is not the way to go.

Bat Guano

Guano consists of the droppings and remains of bats. It’s rich in soluble nitrogen, phosphorus and trace elements.
Bat guano can be thousands of years old, and is generally mined in sheltered caves (not very eco-friendly).
Older guano will contain higher levels of phosphorus whereas newer guano will contain Nitrogen.

Since there’s a limited supply fertilizer guano can be quite expensive.

Sea Bird Guano

Sea bird guano is high in nitrogen and other nutrients. South American Sea Bird guano is the world’s best due to the Humboldt Current. This current keeps the rain from falling making the decomposition of minirals minimal.

It’s nutrient levels will vary depending on where the guano comes from.

Gypsum (Hydrated Calcium Sulfate)

Gypsum is used to lower the soil pH, improve drainage and aeration. It’s also used to hold or slow the rapid decomposition of nitrogen.
This is rarely used indoors.

Hoof and Horn Meal

Hoof and Horn Meal is a excellent source of slow*-release Nitrogen. Fine-ground horn meal makes Nitrogen available quicker and has few problems with fly maggots. Soil bacteria must break it down before it is available to the roots. Apply it 2 to 3 weeks before planting.

It remains in the soil for six months or longer. Hoof and horn meal contains from 6% to 15% Nitrogen and about 2% Phosphoric acid.

Horse manure

Horse manure is readily available from horse stables and racetracks. Use horse manure that has straw or peat for bedding since wood shavings could be a source of plant diseases. Straw will also increase Nitrogen levels.

Compost horse manure for 2 months or longer before introducing it to your garden. This composting process will kill unwanted weed seeds and will make better use of the nutrients.

Nutrient levels in horse manure

  • 0.6% Nitrogen
  • 0.6% Phosphorus
  • 0.4% Potassium

These levels may differ depending on where you’re getting it.

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Kelp is the Cedilla of trace minerals. It should be deep-green, fresh and smell like the ocean. Seaweed contains 60 to 70 trace minerals that are already chelated. This means that the nutrients are water soluble and mobile in the soil.

Make sure to check the label to ensure all elements are not cooked out.

Oyster Shells

Oyster Shells are ground and normally used a calcium source for poultry. They contain up to 55% calcium and traces of many other nutrients that release slowly. Not practical to use indoors because they breakdown too slowly.

Paper Ash

Paper ash contains about 5% phosphorus and over 2% potash. It’s an excellent water-soluble fertilize but do not apply in large doses because the pH is quite high.

Be careful, if you take paper with in, it can be  full of toxic inks.

Pigeon Manure

Pigeon Manure has a very high concentration of nitrogen but is difficult to measure. It can be used in the same fashion as chicken manure.

Rabbit Manure

Rabbit Manure is also excellent fertilize but can also be difficult to find in sufficient quantities. Use rabbit manure as you would chicken or pigeon manure. According to John McPartland, rabbit manure is on of the best fertilizers.

Potash Rock

Potash rock supplies up to 8% potassium and may contain many other trace elements. It releases too slowly to be practical indoors.

Seaweed Meal, aka Kelp meal

Seaweed meal and/or kelp meal is harvested from the ocean or picked up along the beaches. Once harvested it’s cleaned of salty water, dried and grounded into a powdery meal.
This meal is packed with potassium (potash), many trace elements, vitamins, amino acids and plant hormones. The nutrient content varies according to the type of kelp and its growing conditions.

Seaweed meal is easily assimilated by the plants and contributes to soil life, structure and nitrogen fixation. It may also help the plants resist many diseases and withstand light frosts. Kelp meal will also ease transplant shock.

Liquid Seaweed

Liquid Seaweed contains nitrogen, phosphorus and potash in a chelated form. It also contains many plant hormones.

Apply a diluted solution to the soil for a quick cure of nutrient deficiencies. Liquid seaweed is also great for soaking seeds and dipping cuttings and bare roots before planting.

Sheep Manure

Sheep Manure is high in nutrients and makes a wonderful tea. It’s important to compost the manure before usage.

Sheep Manure Nutrient content

  • 0.8% Nitrogen
  • 0.5% Phosphorus
  • 0.4% Potassium
  • Full range of trace elements.

Shrimp & Crab Wastes

These wastes contain relatively high levels of Phosphorus

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Potassium Sulfate

Potassium Sulfate is normally produced chemically by treating rock powders with sulfuric acid. That said, some companies do produce a concentrated natural form.

The sulfate of potash is generally extracted from Salt Lakes.

Swine Manure

Swine manure, generally mixed with Alfalfa, is a centuries old fertilizer used to treat soil. It has a high nutrient content but is slower acting than cow and horse manure.

Average Nutrient levels of Swine Manure

  • 0.6% Nitrogen
  • 0.6% Phosphorus
  • 0.4% Potassium
  • Full range of trace elements

Wood Ashes

Hardwood supplies up to 10% potash and softwood about 5%.
Potash leaches rapidly, you should collect the ash soon after burning and store it in a dry place.

Once ready, apply in a mix with other fertilizers at the rate of 1/4 cup per 3 gallon pots (25 cl per 11L).
The potash washes out of the wood ash quickly and can cause compacted, sticky soil.

Avoid using alkaline wood ashes in soil with a pH above 6.5 as it may raise it too much.

Worm Castings

Worm casting is a fertilizer produced from earthworms. They digest humus and other decomposing organic matter. After digesting it, they excrete (poop) the residue. This “residue” contains varying amounts of nitrogen and other elements.

These castings are an excellent source of non-burning soluble nitrogen as well as an excellent soil amendment. It will promotes fertility and soil structure.

Mix with the potting soil to form a rich, fertile blend. Pure worm castings look like coarse graphite powder and are heavy and dense.
Do not add more than 20% worm castings to any mix. They are so heavy that root growth can be impaired.

Final Note:

Nutrient levels in organic fertilizers may vary greatly depending on the source, age, erosion, climate… Make sure you ask the exact nutrient content before purchasing anything.

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Alright folks that’s it for this one! We’ll be updating this page as our research goes forward
Until next time, Be safe and grow easy!

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