The Best Cannabis Fertilizers of 2024 (Indoor + Outdoor)

This post explains everything about cannabis nutrients and fertilizers during marijuana cultivation. Get an in-depth, unbiased look at which nutrient products to buy.

Note: THC University is not being compensated by any of the companies we mention. Our selections are based entirely on merit.

What type of fertilizer does cannabis need to grow and thrive?

Fertilizer types

Synthetic fertilizers

Synthetic fertilizers are man-made and produced through chemical processes. They’re formulated to contain precise ratios of essential nutrients, typically in a water-soluble form that cannabis crops can easily absorb.

Pros:

Fast-acting: Synthetic fertilizers provide nutrients that are readily available to marijuana plants, leading to quick, healthy growth and visible results.
Precise nutrient control: These fertilizers allow for accurate measurement and control of nutrient ratios, making it easier to address specific deficiencies.
Consistent results: Because they are chemically manufactured, synthetic fertilizers offer uniformity and consistency in nutrient content.

Cons:

Nutrient buildup: Overuse can lead to the accumulation of salts in the grow medium, causing nutrient lockout and potential toxicity to plants.
Environmental impact: Runoff from synthetic fertilizers can contribute to water pollution, affecting aquatic ecosystems.
Soil health: Prolonged use may harm beneficial soil microorganisms, reducing soil fertility over time.

Organic Fertilizers

Organic fertilizers are derived from natural sources such as plant material, animal manure, compost, and other organic matter. They provide nutrients in a form that is gradually released into the soil as they decompose.

Pros:

Improves soil health: Organic fertilizers enhance soil structure, increase water retention, and promote the growth of beneficial microorganisms.
Sustainable: They are renewable and environmentally friendly, reducing the risk of pollution and promoting long-term soil fertility.
Lower risk of nutrient burn: The slow-release nature of organic fertilizers minimizes the risk of over-fertilization and nutrient burn.

Cons:

Slow release: Nutrients are released gradually, which may not provide an immediate boost to plants in need.
Variable nutrient content: The nutrient ratios in organic fertilizers can be less precise, making it harder to address specific deficiencies.
Frequent application: May require more frequent applications to maintain nutrient levels, especially in high-demand growing environments.

Hybrid Fertilizers

Hybrid fertilizers combine elements of both synthetic and organic fertilizers. They aim to provide the immediate availability of nutrients found in synthetic fertilizers with the long-term soil health benefits of organic fertilizers.

Pros:

Balanced nutrient release: Combines quick nutrient availability with the sustained release of organic components.
Enhanced soil health: Improves soil structure and microbial activity while providing consistent nutrient levels.
Versatile: Can be tailored to meet the specific needs of different stages of growth and growing conditions.

Cons:

Cost: Hybrid fertilizers can be more expensive than purely synthetic or organic options due to their complex formulations.
Management complexity: Requires careful management to avoid nutrient imbalances and ensure that plants receive the right mix of fast-acting and slow-release nutrients.

Our recommendation: Considering overall efficacy, hybrid fertilizers can be considered the most effective for a wide range of growing conditions. They provide immediate nutrient availability, enhance soil health, and offer a balanced approach that mitigates the drawbacks of using purely synthetic or organic fertilizers alone.

This combination makes hybrid fertilizers a versatile and reliable choice for cannabis cultivation—but use what you feel is best for your specific grow.

Learn how to water cannabis plants.

Cannabis plants need the following nutrients

Cannabis plants require a variety of macronutrients and micronutrients to grow healthily. Specifically, cannabis thrives on an NPK ratio, or Nitrogen (N), Phosphorus (P), and Potassium (K). Here’s a detailed look at these essential nutrients and the quantities needed:

Macronutrients:

Nitrogen (N): Essential for vegetative growth, nitrogen is a key component of chlorophyll, the molecule that plants use to convert sunlight into energy through photosynthesis. It also plays a crucial role in the development of amino acids, the building blocks of proteins.
Quantity: During the vegetative stage, cannabis plants need higher levels of nitrogen, typically 2-5% of the total nutrient mix.
Phosphorus (P): Important for root development and flowering, phosphorus is vital for energy transfer within the plant and is a major component of ATP (adenosine triphosphate), the energy currency of cells.
Quantity: During the flowering stage, cannabis plants require more phosphorus, usually 1-3% of the total nutrient mix.
Potassium (K): Critical for overall plant health, potassium helps regulate various physiological processes, including water uptake, enzyme activation, and photosynthesis. It also enhances the plant’s ability to resist stress and disease.
Quantity: Potassium is needed throughout the grow cycle, generally 2-5% of the total nutrient mix.

Micronutrients:

These are needed in smaller quantities but are still essential for healthy plant growth:

Calcium (Ca): Important for cell wall structure and stability.
Magnesium (Mg): Central component of the chlorophyll molecule, necessary for photosynthesis.
Sulfur (S): Integral to amino acids and proteins.
Iron (Fe): Vital for chlorophyll production and function.
Manganese (Mn): Involved in enzyme activation and photosynthesis.
Boron (B): Crucial for cell wall formation and nutrient transport.
Zinc (Zn): Important for enzyme function and growth regulation.
Copper (Cu): Needed for reproductive growth and enzyme activity.
Molybdenum (Mo): Essential for nitrogen fixation and enzyme function.

How to pick a cannabis fertilizer

There are lots of ready-made fertilizers to choose from, but you’ll have to be a bit cautious and pick the right fertilizer (in the right quantities) depending on a few factors, including:

Indoor vs. outdoor grow environment

Indoor: Controlled environments allow for precise nutrient management. Synthetic or hybrid fertilizers are often preferred for their consistency and ease of control. For indoor setups, liquid fertilizers are usually easier to manage and integrate well with automated systems.
Outdoor: Organic fertilizers can improve soil health over time and support sustainable gardening practices. They also work well with the natural ecosystem. The benefits for growing cannabis outdoors include slow-release nutrients found in organic options, which steadily feed the plants.

Soil vs. hydroponics

Soil: Organic fertilizers enhance soil structure and microbial life. They are suitable for growers who aim to maintain or improve soil health. Soil-grown cannabis typically enjoys the benefits of natural nutrient cycling and improved flavor profiles.
Hydroponics: Synthetic fertilizers are designed for hydroponic systems, providing immediate nutrient availability in a soil-less medium. They allow for precise control over nutrient levels, which is crucial for maximizing yields in hydroponic setups.

Growth stage

Seedling:

Requires minimal to zero nutrients—the plant is very delicate at this stage. Choose a soil that does not include fertilizers or chemicals to ensure your seedling thrives.

Vegetative:

High nitrogen is essential for leaf and stem development.
Look for fertilizers with a higher N-P-K ratio emphasizing nitrogen.

Flowering:

Higher phosphorus and potassium are needed for bud formation and flowering.
Select fertilizers with lower nitrogen and higher phosphorus and potassium.

Budget and availability

Cost:

Synthetic fertilizers are generally more cost-effective and widely available.
Organic and hybrid fertilizers may be more expensive but can offer long-term benefits to soil health and plant quality.

Ease of Use:

Consider how easy the fertilizer is to use and apply. Liquid fertilizers are straightforward to mix and apply, while granular options may require more effort. Ease of use can significantly impact the efficiency of your cultivation process.

Brand reputation

Reputation:

Research brands and read reviews from other cannabis growers. Established brands with positive feedback are more likely to provide reliable products. Brands like FoxFarm, General Hydroponics, and Advanced Nutrients are well-regarded in the cannabis community.

Specific recommendations:

Look for fertilizers specifically formulated for cannabis, as they are designed to meet the plant’s unique nutritional needs. We’ll walk through some good options next.

The best store-bought fertilizer for cannabis plants [2024]

Based on factors like cost, effectiveness, reviews and results—the best cannabis fertilizers come from General Hydroponics.

General Hydroponics offers a number of cannabis nutrients that offer total nutrition as a mineral-based plant food. The company has been around for 45 years and delivers consistently solid, budget friendly cannabis fertilizers.

Top General Hydroponics fertilizer products:

Prorelease: GH’s Controlled Release Fertilizers (CRF) are granulated and designed to be applied directly to a plant’s root zone. CRFs slowly and predictably release fertilizer over time, continuously feeding for months with only a single application. This allows for unprecedented ease of use and control for professional growers – reducing labor costs while providing peace of mind.
Maxi Series: MaxiGro™ and MaxiBloom™ make up Maxi Series™, a duo of standalone, one-part powdered formulas with primary, secondary and micronutrients. Because these dry nutrients are designed to dissolve quickly in water, they’re highly concentrated formulas that are easy to use, easy to store and easy to love. And since Maxi Series provides elements essential for proper plant nutrition, it helps grow vigorous plants, strong roots and large flowers for great results.
Biothrive: BioThrive® consists of BioThrive® Grow 4-3-3 and BioThrive® Bloom 2-4-4 and is brought to you by General Organics®. BioThrive® Grow 4-3-3 provides plants with essential nutrients for roots, stems, and foliage while BioThrive® Bloom 2-4-4 offers flowering and fruiting plants essential nutrients for superior blooms and bountiful harvests. BioThrive Grow and BioThrive Bloom are ideal for all types of plants, and can be used with a wide variety of garden soils and potting mixes. General Organics provides gardeners with a superior line of plant foods and supplements.
Floranova: FloraNova is a liquid base fertilizer with a patented formula. It’s a concentrated and robust recipe your plants will love, in an easy-to-use liquid format you’ll love too. Use nearly any way you grow: in hydroponics, with soilless mixtures and potted plants, or for garden-grown plants in continuous liquid feed programs. No matter the environment, FloraNova is designed to help you grow vigorous plants.

Other great store-bought cannabis fertilizers

BIOCANNA

BIOCANNA is CANNA’s line of nutrients that’s based on naturally derived products. BIOCANNA fertilizers are organic in composition and were developed specially for cultivation in soil and potting mixes.

CANNA protects the production process from sourcing raw materials to presenting the final product, so you are guaranteed the best result. High quality proves itself.

Jack’s 321

Jack’s Nutrients is a collection of formulas that gives you choices that work for many different controlled environments without the hype or confusion of extravagant names and crazy labels. Real fertilizer to get you real results.

The Jack’s 321 kit is designed to allow you to tweak your Nutrients to achieve your balance of Part A and Part B. Some growers follow Jack’s 321 program with this combination of formulas and achieve the elusive flexibility and stability in many different growing environments.

Added bonus: Jack’s lasts for a long time.

Nectar of the Gods

The Nectar of the Gods nutrient lines offer very solid results, but can require a number of different products throughout the grow process.

Something like Gaia Mania is solid as a careful blend of organic materials, enzymatically processed to extract only proteins and humates. This digestion process is the beginning step in the absorption of vitamins, acids, and minerals by the plant. Gaia Mania has the ability to feed plants immediately and is also designed to promote microbial populations in your medium, offering greater protection to plants’ root systems.

The best cannabis fertilizer for beginner growers

Based on simplicity for the grower, cost, and efficacy, the easiest way to fertilize cannabis plants is with a living soil like BuildASoil.

Living soil is not sterilized during the manufacturing process and as a result it will contain a plethora of life, including beneficial mites, fungus and microbes.

BuildASoil’s Light Recipe Soil is balanced, gentle, and perfect for beginner growers looking to avoid careful labor involved in balancing nutrients during the grow. This compost-based soil is excellent for starting seeds or full term growth. All you need to do is keep the soil moist and you’ll end up with a solid yield.

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