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Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

The best fertilizers, nutrients, or soil for your cannabis plants will provide important nutrients and an optimal growing environment to maximize yield from your cannabis plants.

There are a ton of different brands of nutrients, soils, and supplements available to cannabis growers. The list below contains a few good options that have really good feedback based on science and growers who’ve used them.

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Why are nutrients important to cannabis plants?

Nutrients and fertilizer are important to your marijuana plants if you want to increase flower quantity and quality at harvest. Nutrients are essential whether you’re growing in plain soil or with hydroponics.

Maintaining your soil’s PH level between 5.5 and 6.5 is another critical factor. This will allow your plants to absorb critical nutrients like nitrogen, phosphorus, potassium (referred to as NPK), calcium, magnesium, boron, copper, iron, manganese and zinc. Before I get to the best nutrients let’s briefly review the types of marijuana nutrients and fertilizers on the market.

Types of Cannabis Nutrients or Fertilizers:

The type of cannabis nutrients currently on the market are

  • Organic nutrients containing a wide range of compounds like bone meal, bat guano, worm castings, etc.
  • Solid & Liquid NPK nutrients which contain Nitrogen, Phosphorus, Potassium (NPK), and sometimes more.
  • Pre-blended, concentrated growing mediums such as “soilless” potting blends.
  • Soil Microbes (Rhizobacteria).

What’s the proper NPK level for Cannabis Nutrients?

Vegetative phase focused NPK products are high in nitrogen needed for vegetative stage growth, while Flowering focused NPK products have a high phosphorus content for flower development.

NPK nutrients come in various blends meant to benefit one stage of plant growth over the other. Believe it or not, there is no exact level of NPK that’s perfect for cannabis growing.

Instead, it’s generally understood that cannabis plants need more Nitrogen, less Potassium and Phosphorous during the vegetative phase, and less Nitrogen/more Potassium and Phosphorous during the flowering phase. 

Growers tend to follow those guidelines but use their own individual ratios of N-P-K. A good example would be 7-4-6 for the vegetative phase and 2-9-9 for flowering.

Not all of the fertilizers mentioned below are NPK fertilizers. You can use organic cannabis nutrients and soil microbes in addition to the NPK fertilizers or use them alone.

Which Cannabis Nutrients Do I Recommend?

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

I personally recommend going with a basic three part NPK nutrient kit. The nutrient kits from General Hydroponics and Fox Farm are good to consider if you only want the basics and nothing fancy. Follow the guidelines above as well as the directions on the bottle, and you’ll be fine.

If you want to consider using additional secondary nutrients like the My Weed Minerals described below, feel free. But secondary nutrients are optional.

 

 

 Cannabis Fertilizer – Nature’s Living Soil: Super Soil Concentrate

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | WeedBest Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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Super Soil Concentrate – the easiest marijuana fertilizer to use:

Nature’s Living Soil is a fully organic Non-NPK soil concentrate formulated specially for marijuana growers. Concentrate means you should mix this nutrient rich concentrate with regular soil. It’s also known as “soilless,” a term used to describe a soil-free growing medium.

If you feel growing cannabis is enough work already, Nature’s Living Soil may be the best option for you. It doesn’t require much work aside from initial mixing then watering until you harvest your huge marijuana plants.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

This five pound bag mixes into 25 gallons worth of super soil treated planters.

Super Soil Concentrate’s Quality Marijuana Nutrients:

Super soil marijuana fertilizer contains a long list of organic ingredients based on the recipe developed by well known marijuana cultivator SubCool. The ingredients are as follows:

Organic Earthworm Castings, High Quality Bat Guano, Blood Meal, Bone Meal, Fish Bone Meal, Alfalfa Meal, Kelp Meal, Dolomite Lime, Azomite, Epsom Salt, Coconut Water Powder, and Aloe Vera.

Super soil organic marijuana fertilizer also contains a long list of beneficial microorganisms. The manufacturer recommends Super Soil cannabis fertilizer within two weeks of opening the bag. If you won’t use the whole bag at once, you can store it in a cool dry place indefinitely. Re-moisten the soil before reuse and you’re ready to go.

Some users report Super Soil smells similar to manure. The smell is normal and dissipates once mixed with regular soil.

Super Soil Concentrate marijuana fertilizer – Directions for use:

Nature’s Living Soil recommends not planting seedlings directly into the soil. They recommend planting your seedlings into a small buffer zone of regular soil, and allowing them to grow into the mixed super soil. Water normally once done.

You do not need to add any other nutrients to your cannabis plants once you’ve potted with Nature’s Living Soil. The soil will bring your PH to a safe range, and provide all necessary nutrients for your marijuana plants.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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Nature’s Living Soil Super Soil marijuana fertilizer is one of the best – and laziest fertilizers available for your use. Look no further than the stellar reviews the soil has received from cannabis growers. Growers report being very happy, adding that their plants grow vigorously. One grower added that after they transplanted their seedlings, the increased daily growth was blatantly obvious.

Can you use regular soil to grow cannabis?

Yes, you can use regular soil or soil mixed with a concentrate like Super Soil to grow your cannabis. No matter which you choose, make sure you maintain the proper pH levels so nutrients can be absorbed. Also make sure any NPK levels from the combined super soil (if it has any) plus any other added nutrients does not exceed the necessary levels.


Click Here to view Super Soil Organic Concentrate on Amazon..com


 My Weed Minerals Organic Trace Micro Nutrients for Marijuana by Eco Organics

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | WeedBest Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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My Weed Minerals – 62 nutrients for your marijuana:

Eco Organics has formulated organic cannabis nutrients meant to help your buds grow abnormally large. My Weed Minerals Organic Trace Micro Nutrients for marijuana contains critical divalent ionic minerals essential for metabolic synthase transformation in the plant’s trichomes, making for higher potency marijuana.

This Non-NPK, ocean water derived liquid concentrate marijuana fertilizer contains 62 nutrients. They activate your plant’s genetics during late stage growth in order to produce larger buds and tops. These minerals are derived from ocean water, but don’t worry, there’s no salt in this marijuana fertilizer. Approximately 95% is filtered out with the other 5% remaining present as essential chloride nutrients for your plant.

In addition, My Weed Minerals nutrients are meant to work in addition to any other NPK fertilizer you may wish to use.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

My Weed Minerals will last you a long time:

This 64oz concentrate will last a long time when you consider the mixing ratio of 10ml per gallon of water. With that mixing ratio you’ll get an impressive 189 gallons of nutrient infused water for your marijuana plants.

This may be one of the best value marijuana nutrients on the market. Not only can you use these cannabis nutrients for root feeding, but you can also use them in a foliage spray.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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Directions for use are conveniently located on the side of the bottle. Directions for all environments are included. My Weed Minerals is a little bit more labor intensive than super soil concentrate because you need to add it to water then manually spray or water your plant. Although unlike other liquid marijuana nutrients, My Weed Minerals doesn’t come as separate bottles that need to be mixed.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

This is the only marijuana fertilizer we’ve come across that’s derived from the ocean and provides ionic minerals. If you’re willing to experiment a bit, we think it’s worth a shot. There are a few reviews for the product so far and they’re all positive.

 

 Bloom City Complete NPK 16 Week Cannabis Grow Kit

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | WeedBest Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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The folks at Bloom City know you’re stressin’ about growing your seedlings into tall luscious cannabis plants. Why bother with the measuring, mixing, and feeding-frequency guesswork if you don’t have to? Bloom City developed a complete NPK veg and bloom cycle nutrient kit sufficient for bringing 4 to 8 marijuana plants through a full 16 week grow cycle.

Quality Cannabis Nutrients for Any Environment:

This Bloom City marijuana nutrient kit will work in soil or soil-less mediums, indoors or outdoors. It contains high quality, organic marijuana nutrients like alfalfa meal, poultry meal, feather meal, kelp meal, crustacean meal, fish meal and ascophyllum nodosum.

This kit is not intended for purely hydroponic setups. So if you have a hydroponic setup, you may want to consider these hydroponic safe nutrients.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

The Bloom City grow kit was formulated by botanists and and plant chemists in Seattle, Washington, so by following the simple steps you know your plants have good science behind them.

Bloom City Nutrient Kit Contents:

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

The Bloom City cannabis nutrient kit comes with easy to follow directions, and seperated nutrients for different cycles of plant growth. The kit contains one 5lb bag of 5-3-2 nutrients for the grow phase, a bottle of soil conditioner, one 5lb bag of 4-5-4 nutrients for bloom phase, instructions and a measuring cup.

This kit makes home growing easy, safe and stress free. It doesn’t come with soil, and yes, it will work for autoflowers as well!

Bloom City Cannabis Nutrients – What people are saying:

I’ve researched what people who purchased this marijuana nutrient kit are saying post-purchase. Buyers seem to be pleased with their results overall. They appreciate the simple instructions and ease of use.

The fertilizer reportedly mixes into the soil quite easily. One user reported that no additional care was needed for their plants beyond this cannabis nutrient kit, and they were very pleased with the plant yield.

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

If you don’t want to worry about whether you’re overfeeding  or underfeeding, and like having all the steps laid out for you, then this kit is definitely for you.

 

 Mammoth P Soil Microbes – Scientifically Proven Increased Yields 16%

Best Nutrients and Fertilizers for Growing Cannabis | Marijuana | WeedBest Nutrients and Fertilizers for Growing Cannabis | Marijuana | Weed

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Mammoth P is professionally developed soil microbes. These microbes, also known as rhizobacteria, act as a beneficial addition to your plant’s ecosystem. Certain genus of bacteria have been found to increase yield and accelerate time to flowering in certain crops.

If you’re not growing your cannabis outdoors or even in a specific outdoor geographic region, you’ll be missing out on these beneficial microbes that exist naturally in those environments. Mammoth P is the answer to that.

Mammoth P was tested specifically on cannabis, and proven to increase yields by 16% over industry-standard fertilizers.¹ This means Mammoth P is one of the best cannabis nutrients on the market.

It has several other benefits to your cannabis plant as well. The first is that the microbes produce nutrients in the soil that benefit bud production. Second is the increased phosporus levels that help keep your plants’ internodes short.

Plants treated with Mammoth P in the study cited at the end of this review grew 8.9% taller on average.

In addition, other studies have found that endophytes (bacteria or fungus living on plants) have demonstrated protective activity against pathogens dangerous to cannabis plants (and other plants), and even powdery mildew.²

Watch my video on the benefit of soil microbes like Mammoth P:
Cannabis Soil Microbes | Mammoth P | Recharge | Rhizobacteria | Increase Cannabis Yields 16%!

 

Less Expensive Alternative:

Mammoth P is pretty expensive. Fortunately there are other tried and true alternatives that cost a fraction of the price. One very popular soil microbe brand for cannabis growers is –

Real Growers Recharge

Although it’s a different blend of microbes than Mammoth P, growers are getting incredible results and word of mouth has spread quickly among the home growing community. You can find out more details about Real Growers Recharge by clicking here.

If you go with any type of soil microbes, you should consider supercharging them with Unsulphured Blackstrap Molasses (read my article here). The microbes eat the sugary molasses and create CO2 as a byproduct, which supercharges your plant growth.

 

How long will a 500ml Mammoth P bottle last?

Mammoth P suggests 1-4ml per gallon of water. Assuming you use between 2 and 4ml per gallon, a 500ml bottle will make you 125-250 gallons of water.

Tips for use:

  • Mammoth P reduces the need for a separate enzyme additive. That said, growers have used this safely with other supplements and in cloners.
  • It’s safe to use in soil, super soil, and soilless applications.
  • Try to finish Mammoth P within 6 months of opening. Unopened these will stay fresh for at least 2 years.
  • The microbes are designed to bounce back from a frozen state, so no need to worry if you’re shipping these through a cold climate.
  • What if Amazon runs out of stock? LED Grow Lights Depot also carries Mammoth P if Amazon runs out.

Click Here To Check Out Mammoth P Soil Microbes On Amazon


Word of caution about overusing marijuana nutrients:

Marijuana nutrients or fertilizers can be dangerous to your plants if you don’t follow instructions. Cannabis plants are delicate plants. Despite being a type of “weed” they can easily be mishandled, resulting in a total loss. This can result from over or under-watering, over or underfeeding, among other factors.

How to tell if you overused cannabis nutrients:

There’s a symptom called nutrient burn where your cannabis leaves turn yellow or look “burnt” a considerable amount of time prior to harvest. This is due to overfeeding with marijuana nutrients.

Separately, nitrogen toxicity causes leaves to turn dark green and shiny. If your leaves look like that – lighten up on the nitrogen!

However, yellowing near your plant’s base right before harvest is normal, so it’s important to distinguish if it’s natural or not. You should know based on how much nutrients you’ve been feeding.

If you’re unsure, using a little bit less nutrients is better than risking your plant. If you’ve accidentally overfed one of your marijuana plants, you can flush them with pH neutral water, but don’t flush them the week before flowering.

If you feel uncomfortable measuring out nutrients on your own, it’s best to purchase a predefined kit like the Bloom City nutrient kit mentioned above.

Do nutrients affect the taste of marijuana?

Nutrients will only affect the taste of your cannabis if they’re used improperly. Why does weed taste like nutrients in the first place?

Marijuana nutrients get absorbed through roots or through the leaves if you’re using a foliar spray. A bad taste from any particular nutrient is at risk of remaining in the plant if you keep feeding nutrients too soon before harvest.

You can avoid growing marijuana with nutrient taste by cutting nutrient use completely as you approach harvest time.

You can also “flush” the plant with plain, clean water to help clear any remaining nutrients from the system. That doesn’t mean over-water. It simply means using a normal amount of pH nuetral, nutrient-free water.

Some cannabis growers have even reported larger buds and better taste when they stopped using nutrients as harvest time approached compared to using nutrients right until harvest.

You may notice the cannabis plant leaves turn yellow and die prior to harvest.

cannabis leaves before harvest

That phenomenon may accelerate when you pull the nutrients. That’s due to nutrient deficiency, but that’s exactly what you want as long as you’re close to harvesting the bud.

Want more growing tips? Check out my Guide to Maximizing Your Indoor Cannabis Yields. Also check out my guide on Grow Light Hang Height, and Learning about Proper Grow Light Strength (PPFD levels).

FAQ:

Do hydroponic nutrients work in soil or solid grow media?

Yes, hydroponic nutrients will work in soil or solid grow media.

Do nutrients affect the taste of weed?

Nutrients only affect the taste of weed if they were left in the plant too soon before harvesting. You should stop using nutrients a few weeks before harvest. Only use clean water prior to harvest.

Why are my marijuana leaves turning yellow before harvest?

This is due to nutrient deficiency, which is a normal occurrence before harvest due to the fact you stop feeding nutrients a few weeks early. If this happens during the vegetative phase, your plant may be experiencing a different ailment.

How much weed nutrients to use?

Always follow the directions on the bottle. If you notice an adverse reaction try decreasing the amount of nutrients.

Do marijuana nutrients affect THC?

Every nutrient is different. Some manufacturers may have run experiments to determine if THC is affected or not.

Do soil microbes affect plant size?

Mammoth P soil microbes were scientifically proven to increase the size of cannabis plants. They may or may not affect the size of other plants. Other brands and strains of microbes may or may not have the same effect.

What NPK nutrients for growing cannabis?

Believe it or not, there is no exact level of NPK that’s perfect for cannabis growing.

Instead, it’s generally understood that cannabis plants need more Nitrogen, less Potassium and Phosphorous during the vegetative phase, and less Nitrogen/more Potassium and Phosphorous during the flowering phase. 

Growers tend to follow those guidelines but use their own individual ratios of N-P-K. A good example would be 7-4-6 for the vegetative phase and 2-9-9 for flowering.

Can you use regular soil to grow cannabis?

Yes, you can use regular soil, or a soil mixed with soilless concentrate.

No matter which you choose, make sure you maintain the proper pH levels so nutrients can be absorbed. Also make sure any NPK levels from the combined super soil (if it has any) plus any other added nutrients does not exceed the necessary levels.

References:

  1. Conant, R., Walsh, R., Walsh, M., Bell, C. and Wallenstein, M. (2017). Effects of a Microbial Biostimulant, Mammoth PTM, on Cannabis sativa Bud Yield. Journal of Horticulture, 04(01).
  2. Lyu, Dongmei et al. “Plant Growth-Promoting Rhizobacteria For Cannabis Production: Yield, Cannabinoid Profile And Disease Resistance”. Frontiers In Microbiology, vol 10, 2019. Frontiers Media SA, doi:10.3389/fmicb.2019.01761. Accessed 12 Oct 2019.
  3. Caplan, Deron & Dixon, Mike & Zheng, Youbin. (2017). Optimal Rate of Organic Fertilizer during the Flowering Stage for Cannabis Grown in Two Coir-based Substrates. HortScience: a publication of the American Society for Horticultural Science. 52. 10.21273/HORTSCI12401-17.
  4. Bernstein, Nirit & Gorelick, Jonathan & Zerahia, Roei & Koch, Sraya. (2019). Impact of N, P, K, and Humic Acid Supplementation on the Chemical Profile of Medical Cannabis (Cannabis sativa L). 10. 10.3389/fpls.2019.00736.

  5. Tang, Kailei & Fracasso, Alessandra & Struik, Paul C. & Yin, Xinyou & Amaducci Stefano. (2018). Water- and Nitrogen-Use Efficiencies of Hemp (Cannabis sativa L.) Based on Whole-Canopy Measurements and Modeling. 9. 10.3389/fpls.2018.00951.

Other References:

Nature’s Living Soil, Bloom City Organics

Nick
 

My name is Nick, and I'm a home grower who spends time writing about indoor growing tools and setups. My goal is for 420ExpertGuide to be a one stop shop for indoor growers to find the information they need.