The Complete Guide to Cannabis Cultivation Nutrients

Updated by Jeff Funk, Master Cultivator & Success Nutrients Lead Formulator
Last Updated: November 10, 2025 
Scientifically Reviewed By: The Organitek Research Team

Cultivating potent, nutrient-rich cannabis plants is an intricate science. This definitive guide, originally written by the Three A Light crew, has been fully updated and validated by Master Cultivator Jeff Funk. We've simplified the complex details to ensure you avoid critical mistakes, building on the foundational knowledge of the legacy team.

We provide the scientifically backed facts on NPK roles, pH control, and microbial health—all substantiated by external academic research. Because understanding how to avoid cannabis deficiencies is challenging. There's a lot to consider, and making critical mistakes is easy. We know it because we've been there before ourselves.

Read on to elevate your grow from guesswork to guaranteed success. Your plants will thank you (they'll thank us, too–you're welcome).

What's the difference between organic and synthetic cannabis fertilizers?

Organic cannabis fertilizer feeds soil microorganisms, while synthetic fertilizers feed the plant directly. 

The Downsides of Organic Nutrients

• The slow release of cannabis nutrients may cause nutrient deficiency. 

• Organic nutrients can attract pests. 

• Organic nutrients are more expensive to use than synthetic fertilizers.

• The fluctuating nutrient content inherent to organic nutrients can cause deficiencies.

• Organic nutrients are more difficult to apply.
  
  
• You must have a healthy rhizosphere, with ample microorganisms, to digest the organic nutrients and convert them to bio-available plant nutrients. This microbial activity is essential for transforming otherwise inaccessible nutrients, like atmospheric nitrogen or soil-bound phosphorus, into forms that plants can absorb (Youwakim, 2024).

The Upsides of Synthetic Nutrients

• Synthetic nutrients give you more dosage control. 
  
  
• Synthetic nutrients offer regular nutrient consistency. 

• Synthetic nutrients are convenient.

• Synthetic nutrients are more affordable to use compared to organic nutrients.
• Cannabis nutrient deficiency is easier to correct with synthetic nutrients. 
  
  
• Synthetic nutrients may be combined with some Organic nutrient inputs as well. A good example for this practice would be the use of our Mammoth Myco and Organitek Amplify 

Cannabis Nutrient Basics

What nutrients does a cannabis plant need?

The best cannabis fertilizers contain Nitrogen (N), phosphorus (P), and potassium (K). And all programs will also contain a full profile of micronutrients as well. These elements are universally recognized as essential for plant growth, each having a distinct physiological role (Kidder & Hanlon, 2018). Here's how you know when your plant needs each one:

• Cannabis nitrogen deficiency: leaves look pale, turn yellow, curl and drop off.  

• Cannabis phosphorus deficiency: older leaves experience dark spotting, and growth slows. 
• Cannabis potassium deficiency: tips of leaves turn dark and look burnt. 

What are cannabis macronutrients?

Cannabis macronutrients are valuable N-P-K materials in your cannabis nutrient blend and also include magnesium, sulfur and calcium. 

What is NPK Ratio?

NPK Ratio is the percentage by volume of nitrogen (N), phosphorus (P), and potassium (K) your cannabis nutrient blend contains. 

What are secondary nutrients?

Essential secondary nutrients include calcium (Ca), sulfur (S), and magnesium (Mg). These nutrients are often unavailable to cannabis without proper pH level maintenance because pH directly controls the solubility and chemical form of the nutrient ions in the root zone (Latin & Camberato, 2018). Therefore, secondary essential nutrients are critical to adequate cannabis plant development.

Here's how to know when your cannabis plants need secondary nutrients:

• Calcium: growth is stunted, leaves have dead spots with dark green around them 

• Magnesium: veins and outer edges take on a light green or yellow-ish hue

• Sulfur: leaves begin to yellow at the midsection before becoming completely yellow

What are cannabis micronutrients?

Cannabis plants need them in smaller quantities, but micronutrients play an essential role in their physiology. Micronutrient deficiency is somewhat rare, but without them, it's challenging to realize healthy yields and potent plants.

Here's how to know when your plants need cannabis micronutrients: 

• Boron: spotting on new leaves and abnormal or thick growth at tips

• Chlorine:  leaves yellowing, wilting, and stubby roots

• Copper: leaves are shiny or have dark blue or purple undertones

• Iron: new shoots and leaves appear yellow

• Manganese: yellow leaves quickly turning brown

• Molybdenum: leaves turn orange, red, or pink around the edges

• Zinc: fresh leaves don't open up; buds are loose and fragile

Cannabis Grow Types and Nutrients

What cannabis nutrients do hydroponic grows use?

Regardless of the cultivation method, cannabis plants need several essential nutrients to thrive. In hydroponic cultivation, those include: 

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Magnesium
• Sulfur
• Trace Micronutrients and Elements
• Amino Acids and Vitamins

What cannabis nutrients are used for soil grows?

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Magnesium
• And all micronutrients

What cannabis nutrients are used for indoor grows?

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Magnesium
• And all micronutrients

What cannabis nutrients are used for outdoor grows?

While it varies based on your soil, here are the best nutrients for outdoor grows: 

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Iron
• Zinc
• Magnesium
• Copper
• Manganese
• Cobalt 

Cannabis Nutrients for Grow and Feed Stages

What are the best nutrients for cannabis seedlings?

Here are the best nutrients for cannabis seedlings: 

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Magnesium 
• Sulfur 

What are the best nutrients for vegging cannabis plants?

The cannabis vegetative stage lasts between four and twelve weeks. Cannabis plants require significant light and nutrients during this period. 

The best nutrients for the veg stage are the same essential nutrients for any cannabis plant. Still, their NPK ratio will vary as follows: 

• High nitrogen 
• Moderate potassium
• Low phosphorus

*You should consult a nutrient feeding schedule for specifics. 

What are the best nutrients for flowering cannabis plants?

When selecting a fertilizer for flowering, here are the nutrients to look for: 

• Nitrogen
• Phosphorus
• Potassium
• Magnesium 
• Sulfur

*You should consult a nutrients feeding schedule for specifics. 

Cannabis Nutrient Deficiency FAQs

Here are the common issues you may experience if you don't use a proper feeding schedule and an associated kit: 

What is pH imbalance?

pH imbalance indicates the soil's acid-base composition is out of the ideal range.

What is nutrient burn?

Cannabis nutrient burn describes the stress plants are exposed to when they've been given more nutrients than needed in a given growth phase.

What is nutrient lockout?

When plants have the incorrect pH balance, water chemistry, light level, temperature, or nutrients, they won't properly absorb nutrients.

What is nutrient overfeeding?

Overfeeding marijuana nutrients occurs when the roots absorb excess nutrients, preventing water from being transferred through the rest of the plant.

What is nutrient deficiency?

Cannabis nutrient deficiency occurs when plants don't have the essential nutrients required for optimal growth. 

Preparing and Using Cannabis Nutrients

Now you know the nutrients your cannabis plant needs to avoid cannabis nutrient deficiencies, here's how to use them:

So how do you prepare cannabis nutrients? 

• Select the appropriate nutrients based on your cannabis feed chart

• Prepare lukewarm (ideally distilled) water for mixing and add nutrients.

• Measure electrical conductivity (see below) and adjust

• Measure and adjust pH levels

• Ensure your water is still lukewarm, and apply to the roots

When do you stop giving cannabis nutrients?

We recommend you stop feeding between days 63 and 70 of your plant's growth cycle.  

How do you measure nutrients in the soil?

• PPM, or parts per million, can be measured using a TDS (total dissolved solids) meter. 

•  EC or electrical conductivity can be measured using an EC reader. 
  
  
• These tools work by measuring the ability of the solution to carry an electric charge, which is directly proportional to the total amount of dissolved nutrient ions (salts) present (Lopez & Lopez, 2018).
  
  
• Remember these are simply different ways of measuring and interpreting the data. 

Why flush your cannabis plants?

The last step before harvest, flushing, allows plants to absorb any nutrients left in the soil by removing nutrient buildup at the roots.

The Best Cannabis Nutrient Brands

Ask any expert—Success Nutrients is the best brand for achieving cannabis growth success.

Our comprehensive feeding guide eliminates the need for bookmarking a cannabis deficiency chart. And our years of cultivation experience mean we've created essential growth blends that avoid nitrogen deficiency and other common nutritional pitfalls. Our kits include everything you need and nothing you don't. 

Common Questions from Success Nutrients Customers:

Here are some common questions our customers ask:

What nutrients do commercial growers use? 

To replicate the commercial growth experience, stock up on our complete kit to get the nutrients you need, including macro and micronutrients.

Should I use nutrients every time I water my cannabis plants?

No. We recommend regularly flushing with unenhanced water to maximize success; consult our feed chart for dates.

How long should I wait to feed nutrients after I transplant cannabis?

Wait about a month after planting, or until your plants have grown 3-4 sets of true leaves before giving them their first nutrient feed.

What are the best nutrients for flowering in soil?

Our Flowers blend has all the nutrients you need to flower successfully in soil, including nitrogen, phosphorus, potassium, magnesium, and sulfur.

How long to wait after flushing can you harvest?

Flush your plants approximately two weeks before you plan to harvest them.

What does silica do for plants?

Silica improves heat and drought stress, increases insect and fungi resistance, and creates robust and rigid cell walls by depositing amorphous silica SiO2 within the cell wall structure, acting as a physical and chemical barrier (Exley, 2016).

How often should I give my plants nutrients in coco coir?

At the beginning of growth, plants need feeding every one to two days, with feeding intervals increasing to as much as multiple times per day when flowering.

When should I stop using nitrogen during flowering? 

We recommend giving your plants nitrogen via our Flowers blend at regularly scheduled intervals until day 55 of your grow cycle.

Should I use mycorrhizae with my nutrients? 

Yes! We recommend using our Mammoth Myco when transplanting or regularly with hydroponic feedings to ensure a healthy rhizosphere. We also recommend regular incorporation of Amplify to add the healthy bacteria to your soil. This is because mycorrhizal fungi form a mutualistic association with plant roots, significantly increasing the surface area for water and nutrient absorption (Bini, 2022).This is an excellent preventative practice to help boost your grow. 

Are you ready to start your cannabis cultivation journey with Success Nutrients? Click here to shop our lineup of high-quality nutrients for every cultivation scenario. 

References

[1] Youwakim, J. (2024). How Does Soil Biology Impact Nutrient Availability? Decode 6 (A Program of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America). https://decode6.org/articles/how-does-soil-biology-impact-nutrient-availability/

[2] Kidder, G., & L. E. Hanlon. (2018). Plant Essential Nutrients and Their Role. SS-AGR-463/AG462. University of Florida IFAS Extension. https://edis.ifas.ufl.edu/publication/AG462

[3] Latin, P., & Camberato, D. (2018). HO-240-W, Soil pH. Purdue Extension. https://www.extension.purdue.edu/extmedia/ho/ho-240-w.pdf

[4] Lopez, R., & Lopez, S. (2018). Details of Electrical Conductivity Measurements in Greenhouse Production. HO-286-W. Purdue Extension. https://www.extension.purdue.edu/extmedia/HO/HO-286-w.pdf

[5] Exley, C. (2016). Silicon and the Plant Extracellular Matrix. Frontiers in Plant Science, 7, 463. https://www.frontiersin.org/articles/10.3389/fpls.2016.00463/full

[6] Bini, V., et al. (2022). Roles of Arbuscular Mycorrhizal Fungi on Soil Fertility. Frontiers in Fungal Biology, 3, 723892. https://www.frontiersin.org/journals/fungal-biology/articles/10.3389/ffunb.2022.723892/full

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Stay curious, stay clean, stay cultivating —
Jeff Funk
Science may guide the grow, but soul fuels the harvest.
Success Nutrients | Organitek | the science. the experience. the passion. the culture.