Top 10 Best Bud & Bloom Booster Fertilizers

The most effective flowering fertilizers for big buds (aka bloom boosters) Get the high yields & save money by knowing what they’re made of.


Organic Fertilizers

Organic fertilizers are made of natural ingredients. The highest concentration of nutrients come from mineral powders, manures & animal parts. Seaweed and molasses are also used in organic bud foods to promote beneficial bacteria and aide in plant growth processes. The presence of mycorrhizal fungi can help plants absorb organic nutrients like Phosphorus easier.



Overview: A lot of ‘secret’ bud enhancers are simply kelp derivative and soluble potash. Seaweed-derived products have been widely used due to the presence of a number of plant growth-stimulating compounds. Save money on expensive liquid formulas by using kelp meal like Maxicrop, which is harvested Norwegian kelp (Ascophyllum nodosum).


How it benefits flowering: NPK 0-0-17. A natural source of potassium and powerful biostimulants, Maxicrop contains more than 70 minerals, micronutrients, amino acids and vitamins to help with bigger more prolific blooms. Studies have shown that Maxicrop application increased plant root growth by 53-63%. It is also used for cloning & transplanting solutions due to the presence of vitamin B12.


Application: Dissolve 3 tbsp of Maxicrop powder per gallon of water, suitable for all cultivation set-ups. Don’t spray buds it will stick.



Happy Frog Bulb Food


Overview: FoxFarm’s Happy Frog dry fertilizer is a mix of granular organic bud food ingredients such as bone meal, bat guano, and kelp meal. It’s alive with beneficial soil microbes and mycorrhizal fungi inoculant that expand root development enabling plants to feed more aggressively.


How it benefits flowering: NPK 3-8-8. Happy Frog Bulb Food adds humic acid (a natural byproduct of organic matter decomposition) as an organic chelating agent to help release the long-term nutrients contained in this fertilizer for plant absorption.


Application: Follow dosage instructions on label for plant size. It can be mixed into potting mix before final transplant, probed into the root system, or layered onto the topsoil.



BioThrive Bloom


Overview: Vegan plant food. BioThrive is loaded with a myriad of organic substances including alfalfa meal, cane sugar, copper sulphate, glacial rock powder, iron sulphate, kieserite, manganese sulphate, molasses, plant extracts, potassium sulphate, rock phosphate, sodium borate, sodium molybdenate, soybean meal and zinc phosphate.


How it benefits flowering: NPK 2-4-4. Bio Thrive contains the essential nutrients with a hearty dose of carbohydrates (sugars) known to stimulate beneficial microbial activity.


Application: Dilute 4 tsp of BioThrive per gallon of water. This liquid fertilizer is convenient for all types of growing – from hydroponics to in-the-ground soil application.





Overview: CaMg+ is made from an all-natural blend of fermented calcium carbonate and magnesium carbonate, combined with organic acids and sugar chelates.


How it benefits flowering: Calcium and Magnesium help strengthen plants and promote photosynthesis. Combined they make an effective bud hardener. The organic acids and chelates in CaMg+ allow these nutrients to become more readily available for plants to use.


Application: Add 1-2 teaspoons of CaMg+ per gallon of water. For all grow set-ups.



Growilla Bud


Overview: Growilla Bud fertilizer is made from multiple sources of guano, earthworm castings, and fish meal providing a wide range of food for plants and beneficial soil microbes.


How it benefits flowering: NPK 2-5-4. Growilla is designed specifically for plants during their flowering stage. This dry fertilizer is suitable as a stand-alone flowering supplement.


Application: Made for use in soil gardens, soilless mixes and coco coir. Mix it into soil medium during transplants, apply as a probe around the roots or use as a topdress.



Synthetic Fertilizers

Synthetic fertilizers are made of various elemental componds, mostly derived from the chemical chelation of minerals. The chelation process helps transform these minerals into nutrients that are easily absorbed by plants.

Synthetic nutrients work best in hydroponics, aeroponics, or in an easy-flush, low-retention potting mix like 50% perlite, 50% vermiculite.

Jack’s Classic Blossom Booster


Overview:  J R Peters Jack’s Classic Blossom Booster provides the essential NPK nutrients for flowering plants, plus micronutrients in an inexpensive water-soluble powder.


How it benefits flowering: NPK 10-30-20. This classic 1:3:2 nutrient ratio has proven to be the standard for blossom enhancers. A lot of hydro growers are ditching the expensive bottled nutrients and switching over to Jack’s to save money.


Application: One tablespoon of powder per gallon of water. Can be used in any grow set-up including hydroponics & aeroponics.



Flower Fuel


Overview: Flower Fuel is a heavy-duty, high PK blossom booster that contains over 40 ingredients: nutrients, vitamins, hormones, amino acids, essential organic components, and every single micro and trace element.


How it benefits flowering: NPK 0-39-25. This type of high PK bloom booster is used throughout flowering to promote loads of resinous bud sites that develop into big buds right down-to the-stem.


Application: 1/4 teaspoon per gallon of water. Their 250g container treats 200 gallons of water. Suitable for any soil, coco, hydroponic or aeroponic system.



Grow More Hawaiian Bud


Overview: A hard-hitting nutrient ‘boom!’ for plants, Grow More Hawaiian Bud is packed with very high amounts of phosphorus, high amounts of potassium, a little nitrogen and chelated micronutrients.


How it benefits flowering: NPK 5-50-17. Potent PK fertilizers like Hawaiian Bud will help plants stack up heavily with multiple bud sites. This can contribute to heavy yielding big bud harvests when applied correctly.


Application: Suggested use varies at 1/4-1 teaspoon per gallon of water. Be careful of burning plants by overfeeding.



FoxFarm’s Liquid Bloom Trio


Overview: The liquid bloom trio by Foxfarm are not completely organic. While Big Bloom is organic, Tiger Bloom and Grow Big are not. A look at the label ingredients reveals the added synthetic nitrates and phosphates.


How it benefits flowering: These fertilizers are softer in comparison to other chemical fertilizers (no crazy-high levels of P) containing readily-available nutrients combined with organic ingredients and active microbes. These three bottles are sold together in their fully-balanced bud flowering formula.


Application: 2-4 teaspoons per gallon of water. FoxFarm liquid fertilizers can be used in soils, pots, hydroponics & aeroponics.



Osmocote Smart-Release Plant Food


Overview: Most inorganic fertilizers are readily-available, meaning that they do not last long after application and need to be reapplied regularly for best results. Osmocote Smart-Release Plant Food is a slow-release granule fertilizer that feeds plants for up to 4 months.


How it benefits flowering: NPK 14-14-14 controlled release. A balanced high-nutrient long-term synthetic fertilizer. Osmocote was most popular during the 90’s and is a tried-and-true for old-school guerrilla growers.


Application: For 4″ plants 1 teaspoon worked into topsoil or mixed into potting medium.



What Nutrients Does Cannabis Need to Grow?

Nutrients are used like food by plants. Cannabis requires large amounts of mineral nutrients to compose it’s leaves and dense flowers.

  • Well-fed cannabis plants are green and healthy. These nutrients help plants obtain vigorous growth, increased flower production and higher yields of bigger buds. Well-fed plants have a stronger immunity to disease.
  • Underfed cannabis plants subject to slow, stunted growth, yellowing, frail structure and a weak immune system, leading to disappointing, low-quality yields.


There are six major nutrients that cannabis plants require to grow – three of which are obtained from the air and water:

  • Carbon Dioxide (CO2) – Plants simply absorb CO2 from the air, combining it with water and light, to make carbohydrates – a process more commonly known as photosynthesis.
  • Hydrogen (H) – Hydrogen is a part of water (H2O). As plants absorb water, they split the water molecules into hydrogen and oxygen using the energy from the sun.
  • Oxygen (O) – Along with what has been described above, plants consume oxygen through their pores – even at night. This is what’s called respiration. Respiration combines oxygen and the food created during photosynthesis to produce usable energy for plants.

The other three nutrients are Nitrogen (N), Potassium (P) and Phosphorus (K). These nutrients are mostly obtained though a plant’s roots, but can also be absorbed through tissue (i.e. foliar feeding).

Major Nutrients (N-P-K)

What are the three numbers labeled on fertilizers?

NPK (short for Nitrogen, Phosphorus and Potassium) are the major nutrients that plants absorb though it’s roots, or vascular tissue. NPK are the three numbers you see labeled on the front of commerical fertilizers.



The numbers represent the percentage of a nutrient a fertilizer is made of. So for example, a 50-kg bag of 12-24-12 fertilizer would be composed of 12% N, 24% P, and 12% K. To figure out how much K that is you can multiply the weight by the percentage: 50 kg x 0.12 = 6 kg of K.

Nitrogen (N)

  • Nitrogen (a gas) is a major component of amino acids (the building blocks of proteins) and chlorophyll (the energy substance made by plants through photosynthesis). Nitrogen is the most utilized nutrient of a plant’s life-cycle, especially during it’s early stages of growth.
  • Organic sources of N are plant litter, compost, manures, blood meal, feather meal, ect.
  • Synthetic derivatives of N include formulations of urea and ammonium nitrates.

Using Nitrogen for flowering cannabis:

High nitrogen fertilizers have a pronouced effect on cannabis plants, often triggering vertical growth. This is why only moderate levels of nitrogen are applied to blooming cannabis plants in order to keep their buds hard, dense and compact.

Phosphorus (P)

  • Phosphorus (a mineral element) is a component of the complex nucleic acid structure of plants, which regulates protein synthesis. It is important in cell division and development of new tissue, also associated with complex energy transformations in the plant. Phosphorus lets plants use the energy harnessed by photosynthesis to drive it’s metabolism.
  • Organic sources of P include soft rock phosphate, bat guano, steamed bone meal, fish bone meal, and crushed granite.
  • Synthetic derivatives of P are made by treating rock phosphate with either sulfuric acid or phosphorus acid.

Using Phosphorus for flowering cannabis:

High phosphorus availability to plants can lead to additional flower (bud) sites and a healthy root system. The most critical time for cannabis plants to utilize phosphorus is during the beginning of their blooming process (first white hairs), as this is when a big energy change happens in the plant.

Potassium (K)

  • Potassium (a mineral element) triggers the activation of different growth-related enzymes important in many chemical processes taking place during flower production. It also regulates the opening and closing of stomata (pores) during photosynthesis, in part controlling CO2 uptake. Potassium is attributed to playing a major part in the absorption and movement of water, nutrients, and carbohydrates in plant tissue.
  • Organic sources of K include soluble potash (ashes), manures, compost, molasses and kelp meal.
  • Commercially-used K like muriate of potash and sulphate of potash are salts that make up part of ocean saline deposits

Using Potassium for flowering cannabis:

Potassium is a catalyst for carbohydrate metabolism, so when you want your marijuana plants to pack on the carbs, high levels of K are important. Potassium rivals nitrogen as the nutrient absorbed in greatest amounts by plants. It’s best to increase K levels during the midst a plant’s flowering cycle, healthy amounts of potassium will lead to hard, thick and heavy bud yields.

Minor and Micro-Nutrients

Minor and micro-nutrients are essential for healthy plant growth, just used in smaller amounts by plants hence the name.

There are three nutrients classified as minor nutrients. These are:

  • Calcium (Ca) – has a regulating effect in the cells and contributes to the stability of the plant, important in the development of cell walls.
  • Magnesium (Mg) – is a building block of chlorophyll, essential to the process of photosynthesis. Without magnesium, plants cannot process sunlight.
  • Sulfur (S) – is used in the formation of amino acids, proteins, and oils. Sulfur helps develop and activate different vitamins and enzymes.

Seven elements are needed in tiny amounts, these are dubbed micronutrients.

  • These include boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn), nickel (Ni) and chloride (Cl).
  • Being deficient in any of these micronutrients can impair growth.

Nutrient Lockouts

When applying high amounts of fertilizer it’s important to take into account the possibility of a nutrient lockout. This can occur from pH imbalance or excess nutrient buildup. Buildup often happens in mediums that can not be flushed clean of P, as this nutrient has a tendency to cling to other particles in soil.

When too much P is present in soil it binds up calcium, copper, iron, magnesium and zinc making these nutrients unusable. Excess P also has harmful effects on beneficial soil organisms such as mycorrhizal fungi. (Read more)

Compost and Worm Castings as Fertilizer?


There are benefits to using organic matter in soil like increasing water and nutrient holding capacity of the soil, improving soil structure and promoting beneficial microbes.

Compost is often analyzed as a 1-1-1 dilutant fertilizer. However, all compost varies in composition. The nutrient profile of compost depends on what was used to make it.

Worm casting compost made with egg shells (calcium) and banana peels (potassium) are a great organic bud food that you can make at home.

What are Effective Flowering Fertilizers?

Bloom boosters, bud foods and flower fertilizers are terms for nutrient additives meant to be used when a plant is producing flowers (buds). These nutrients are available to plants in the form of organic material (organic fertilizers) or are derived though chemistry procedures (synthetic fertilizers).

What do bloom fertilizers have in common?

  • High proportions of Phosphorus (P) and Potassium (K), to maximize bud formation & growth-related enzymes in the plant.
  • Low proportions of Nitrogen (N), to prevent bud stretching.
  • Calcium (Ca) and Magnesium (Mg) are utilized to aid in dense flower clustering, along with other minor nutrients, micronutrients, and trace minerals.

Organic vs. Synthetic nutrients

  • Organic cannabis fertilizers contain both readily available and long-term nutrient sources. A thriving microbial ecosystem will help plants access these nutrients faster.
  • Synthetic cannabis fertilizers are readily-available nutrients (with the exception of controlled-release fertilizer). These contain chemically chelated nutrients for immediate absorption by plants.

Best Fertilizer for Cannabis Buds Shortlist

MaxicropOrganic0-0-17VIEW PRICE ►
Happy Frog BulbOrganic3-8-8VIEW PRICE ►
Biothrive BloomOrganic2-4-4VIEW PRICE ►
CaMg+OrganicCa5-Mg1VIEW PRICE ►
Growilla BudOrganic2-5-4VIEW PRICE ►
Jack's Blossom BoosterSynthetic10-30-20VIEW PRICE ►
Flower FuelSynthetic0-39-25VIEW PRICE ►
Hawaiian BudSynthetic5-50-17VIEW PRICE ►
Liquid Bloom TrioMixedMixedVIEW PRICE ►
OsmocoteSynthetic14-14-14VIEW PRICE ►

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  1. // Reply

    The organic foxfarms kind works good with the maxicrop.

    1. // Reply

      I agree Dino, Personally a big fan of the Happy Frog fertilizers from Fox Farm, and good ol’ Maxicrop… Maxicrop, or Norwegian sea kelp is a great trace minerals fertilizer/supplement with a little bit of potassium as well. I have seen times personally where a cannabis plant is not growing with the optimum health and vigor, then simply maxicrop (sea kelp) was supplemented to the weed plant and in a matter of hours that plant’s color had changed to a deeper green and had visually gained vigor, eventually flowering and finishing up into some heavy yielding, big-budded chronic. Sometimes the small things may be overlooked in certain soils, adding sea kelp into your soil or onto your plant(foliar feeding) is a reliable way to ensure that hungry cannabis plants get the nutrients they need to grow big and yield hard.

    1. // Reply

      Hi Dino, Many FoxFarm fertilizers ARE organic, such as the Happy Frog dry fertilizers, but others such as ‘Tiger Bloom’ and ‘Grow Big’ are non-organic – read above ^^

    1. // Reply

      wanner find a LED grow light, see this one, anyone used MEIZHI LED grow light?

  2. // Reply

    So for a cheap buy.. is happy frog complete or you need to complete with something else?

    1. // Reply

      Hi Maxime, for a cheap buy, yes it’s a good dry fertilizer complete with all the best nutrients for cannabis during it’s flowering stage. However the size of the plant is also important. Larger plants need more nutrients so they can handle a few cups worth of it each.

  3. // Reply

    Excellent information on fertilizers during Banana flowering stage. Highly informative.

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