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Choosing the best flowering fertilizer is one of the most important factors for achieving more productive plants, dense flowers, and a higher-quality harvest.
In this guide, you will find the best flowering fertilizers according to the type of cultivation, explanations about NPK fertilizer, comparison tables, common mistakes, and specific recommendations for achieving healthier plants and abundant blooms.
How to choose the best flowering fertilizer
Not all fertilizers work the same way, nor do all plants have the same nutritional needs.
To choose the best fertilizer for plants, you must take into account:
The type of cultivation
Depending on the type of cultivation, the best flowering fertilizer will vary.
Below, The Green Brand explains the ways marijuana can be grown and which is the best flowering fertilizer that will maximize your production of CBD flowers.
- Soil cultivation. The best fertilizer for plants in soil usually combines phosphorus, potassium, and organic matter to improve flowering and root development. Additionally, soil helps buffer fertilization errors and maintains beneficial microbiology. Organic and bio-mineral fertilizers usually offer excellent results both indoors and outdoors.
- Coco cultivation. Coco allows for great root oxygenation and very fast growth, although it requires more precise nutritional control. The best flowering fertilizer for coco must incorporate calcium, magnesium, and fast-absorbing micronutrients. Many growers use coco to maximize production during flowering.
- Hydroponic cultivation. Choosing the best flowering fertilizer for hydroponics is essential to maintain rapid and stable nutrient absorption. Hydroponic fertilizers must be completely soluble and compatible with pH and EC control. PK fertilizers are usually the most used in this type of cultivation.
- Indoor cultivation. Indoor cultivation requires fertilizers that can maximize bud production under artificial lighting. The best fertilizer for this type of cultivation usually includes phosphorus, potassium, amino acids, and flowering stimulants. And some growers also use PK boosters to increase resin and production.
- Outdoor cultivation. Outdoors, marijuana plants develop larger roots and need constant nutrition throughout flowering. The best fertilizer for outdoors must improve resistance, boost growth, and favor denser and more aromatic flowers. Organic fertilizers are especially popular because they improve soil microbiology and the final quality of the harvest.
The importance of choosing the best flowering fertilizer
As you know, flowering is the moment when the plant develops buds, which are the most valuable part for growers.
Specific flowering fertilizers contain ideal proportions of NPK and other micronutrients (calcium, magnesium, sulfur) that promote abundant and healthy flowering.
During the growth phase, plants demand higher amounts of nitrogen to develop strong leaves and stems. However, during flowering, needs change completely and phosphorus and potassium become the protagonists.
What we can achieve with flowering fertilizers
- Larger and denser buds. By providing adequate amounts of phosphorus and potassium, buds develop larger, more compact, and with more weight.
- Greater amount of resin and trichomes. Flowering is the stage in which the plant produces the most trichomes, which are those little sacs where cannabinoids and terpenes are concentrated. Fertilizers enriched with sugars or humic acids stimulate this production, which can significantly improve the aroma and also the potency of its compounds.
- Better flavor. Organic fertilizers or those enriched with natural sugars favor the accumulation of terpenes, compounds responsible for the aroma and flavor of the buds. A good nutritional balance avoids the accumulation of salts that could alter the organoleptic profile.
- Uniform ripening. Fertilizers designed for the final stage of flowering (ripening) help all buds reach their optimal point at the same time.
What are the best fertilizers for cannabis flowering?
Among the best cannabis flowering fertilizers available in our catalog are the following:
Flower Power Flowering
Flower Power Flowering is a powder fertilizer designed specifically for the flowering phase of plants. It contains 30% potassium, 15% nitrogen, and 6% phosphorus. Its easy-absorption formula allows plants to quickly take advantage of its benefits, promoting the abundant formation of larger and higher-quality flowers. This product is suitable for use in any growing medium, whether hydroponics, coco, or soil.
Flower
Agrobacterias Bactobloom
Agrobacterias Bactobloom is a soluble powder flowering stimulator, composed of beneficial bacteria that improve the root environment and optimize nutrient absorption. These bacteria favor the production of sugars in plants, which leads to larger, denser, and more resinous buds. Additionally, they contribute to reducing environmental stress and protect against fungi and insects. Ideal for pot cultivation.
Bactobloom Flowering
Boom Nutrients Flowering Boom
Boom Nutrients Flowering Boom is a single-component fertilizer designed to cover the nutritional needs of marijuana plants during the flowering phase, both in intensive outdoor and indoor crops. It has a balanced NPK formula of 5-7-10% so that plants develop thick, large, and aromatic flowers without the need to add other additives or fattening products.
It is an easy-absorption flowering fertilizer, so plants can quickly take advantage of its benefits. Its use is recommended from the first week of flowering in indoor crops and from the continuous appearance of pistils in outdoor crops. Flowering Boom is available in 1L and 5L formats.
Floración Boom
GB Nutrients Bloom
GB Nutrients Bloom is a liquid bio-mineral fertilizer designed to feed marijuana plants during the flowering phase. It has a balanced formula and optimal NPK levels (1-3-5%) that stimulate the development of a greater number of flowering points. It also helps the plant generate abundant buds with a greater amount of resin. Additionally, it improves the compactness, flavor, and aroma of the flowers. It is recommended to apply Bloom twice a week from the start of flowering until root flushing, using a dose of 2-3 ml per liter of water.
Bloom GB Nutrients
Boom Nutrients Organic Bloom
Boom Nutrients Organic Bloom is a 100% vegetable liquid fertilizer, which stands out among similar products because its formulation includes two unique biomolecules: Fucoidan and Alginate, extracted from seaweed.
- Fucoidan. Acts as a plant metabolism stimulator and is capable of improving cell division for the formation of denser flowers. It also reinforces the plants’ ability to resist environmental stress and diseases.
- Alginate. Improves water retention in the substrate, which benefits root hydration. It also favors the absorption of essential nutrients for more vigorous floral development.
Organic Bloom
Biobizz Bio Bloom
Biobizz Bio Bloom is a 100% organic liquid fertilizer with the necessary nutrients for the best development of marijuana plants during the flowering phase. It has a balanced formula of nitrogen, phosphorus, and potassium (2-7-4) and is also enriched with enzymes and amino acids that stimulate exuberant flowering and tasty fruits. This fertilizer also contains trace elements and plant-derived hormones that favor the development of plants with strong stems and vigorous flowering.
Bio Bloom
Bio Bloom can also be used in soil and non-soil substrates, and can be applied from the start of flowering until harvest. A dose of 2 to 4 ml per liter of water is recommended. It should not be used in irrigation systems because it has components that can clog drippers and pipes. It is available in 1L, 5L, 10L, and 20L formats.
Boom Nutrients Delta Boom
Boom Nutrients Delta Boom is a powerful bio-stimulator designed for the cannabis flowering phase. Its formulation is enriched with seaweed extracts, carbohydrates, enzymatic activators, vitamins, and vegetable amino acids, enriched with macronutrients such as nitrogen, potassium, phosphorus, calcium, and magnesium, as well as essential micronutrients such as cobalt, zinc, molybdenum, manganese, sulfur, and boron.
Delta Boom
The application of Delta Boom during flowering increases THCA production, essential oils, and resin density. The result is denser, more compact, and resinous flowers. Additionally, it boosts the plants’ natural defenses and improves nutrient absorption. It can be used in soil, coco, and hydroponic systems. For best results, it is recommended to apply this product in the flowering phase, following the product’s specific instructions.
Atami Bloomstimulator
Atami BloomStimulator is a flowering stimulator designed to help marijuana plants enter the flowering phase faster and more abundantly. This product is perfect for increasing the density and size of the buds, so the plant can develop more compact and resin-loaded flowers.
Bloomstimulator
The main advantage of BloomStimulator is that it accelerates the start of flowering and prolongs it, and thanks to this, the flower production is richer and more abundant. Additionally, this stimulator not only improves the quantity but also the quality of the terpenes.
It is a highly concentrated product that must be diluted in water. It is recommended to add between 0.5 and 1 ml of product per liter of water and apply during irrigation, starting from when the first signs of flowering appear. It is available in various sizes, from 100 ml to 5 liters.
Grotek Monster Bloom
Grotek Monster Bloom is a very powerful flowering stimulator used to increase the size and density of buds on plants. Its formula contains a high concentration of phosphorus and potassium (NPK 0-50-30), key elements for protein and sugar synthesis. This accelerates the plant’s internal processes and strengthens both cell walls and nuclei, which helps develop larger and more compact flowers.
Regarding the dosage and method of use, it is recommended to add 0.3 grams of Monster Bloom per liter of irrigation water. This product should be applied once a week during the bud fattening phase, when they are already well-formed, more or less from the fourth or fifth week of flowering, depending on the variety grown. It is important not to exceed the recommended dose, as its high concentration could cause over-fertilization problems.
Monster Bloom
In the formulation of Monster Bloom, we can find a high content of phosphorus (50%) and potassium (30%), the essential nutrients for abundant and quality flowering. To maximize results, it is suggested to combine its use with other products from the same line, such as Heavy Bud Pro, which provides an extra dose of sugars and further improves the density and compactness of the buds.
Boom Nutrients Big Boom PK 52-34
The function of this Boom Nutrients fertilizer is to fatten the buds of the marijuana plant, so it must be used in the flowering phase. It has become a must-have in the list of the best marijuana flowering fertilizers of 2025 for being one of the products that provides the highest level of phosphorus and potassium.
To take full advantage of its power, it must be used together with a quality flowering fertilizer, a supply of sugars or carbohydrates, a flowering stimulator, and enzymes to renew the roots.
Big Boom PK 52-34 has the peculiarity of having 3 modes of use, depending on the experience of the grower using it. Additionally, it must be taken into account that the doses must be dissolved in 10 liters of water, unlike most cannabis fertilizers, where it is indicated per liter.
Big Boom PK 52-34
Atami Bloombastic
This is an all-terrain product and one of the best flowering fertilizers: it provides extra phosphorus and potassium, as well as carbohydrates and sugars; favoring abundant flowering and fat buds full of resin. Its good reputation follows it around the globe thanks to the incredible results it offers, so it could not be left out of the best flowering fertilizers of 2025.
To use this product correctly, you should pay attention to the recommendations of the Atami Bloombastic table. By adding Atami Bloombastic starting from the 4th week of flowering, the buds will become large and heavy. The nitrogen will give the leaves an intense green, and the sugars and carbohydrates will help in the creation of resin and will increase its flavor.
Bloombastic
Apply between the last 4 and 6 weeks of flowering, combining it with basic nutrients. It is enough to water 2-3 times per week, diluting between 0.5 and 1 ml of fertilizer per liter of water.
BAC Organic Bloom
BAC Organic Bloom is a 100% organic and natural fertilizer, with a balanced formula (NPK: 5-2-5) and other compounds such as alfalfa feed, sugar molasses, or stone flour, so that plants can develop buds of exceptional quality. The product is accompanied by a table provided by the manufacturer, where the method of use, dosage, and frequency are detailed. It can be combined with other fertilizers for flowering, although care must be taken that nutrients do not accumulate excessively in the soil. To avoid this, it is recommended to intersperse water without nutrients once a week to give the soil time to absorb all the product.
Organic Bloom
Undoubtedly, Organic Bloom is an ecological and effective option for growers looking for high-quality flowering in their marijuana plants, and you can also choose between several size formats: 1L, 5L, and 10L.
Atami Bloombastic Terra Box
The Atami Bloombastic Box Kit is a set of fertilizers used for growing plants in soil substrate. This kit includes a selection of products that cover all phases, from growth to flowering, with the aim of providing plants with all the necessary nutrients at each stage.
Bloombastic Terra Box
The composition of these products is enriched with high levels of bio-minerals, specifically phosphorus and potassium, which are essential for abundant and quality flowering. Unlike other stimulants, it does not contain non-assimilable substances such as sodium or chlorine, which guarantees more effective and safe nutrition for the plants.
- Terra Leaves. Fertilizer for the growth phase, favors healthy vegetative development.
- Terra Max. Fertilizer for the flowering phase, ideal for promoting dense and aromatic buds.
- Bloombastic. Cocktail of bio-minerals (NPK 0-14-15) and bio-stimulants that increase weight, aroma, and sugar content in the flowers.
- ATA-Zyme. Product that balances the substrate, breaks down organic waste, and keeps the root system healthy.
- ATA-Rootfast. Root stimulator.
Canna Fertilizer Kit
The Canna fertilizer kit contains everything necessary to carry out a crop of a couple of plants outdoors or one square meter indoors, from start to finish with the best quality products. In total, it consists of 6 fertilizers that are responsible for developing a strong and healthy structure in the plant that will end up offering dense and very resinous flowers.
Components of the Canna Fertilizer Kit
For the growth stage:
- Terra Vega (1L): organic base product that guarantees vigorous plant growth in a short time.
- Rhizotonic (250 ml): root stimulator, to increase the amount of nutrients assimilated by the plant and, therefore, its quality.
- Cannazym (250 ml): its components activate the microorganisms in the medium that break down organic matter remains, transforming them into sugars that the plant can assimilate.
For the flowering phase:
- Cannaboost Accelerator (250 ml): accelerates chlorophyll formation and distributes energy throughout the plant, stimulating flowering.
- Terra Flores (1L): base fertilizer for soil that provides all the nutrients that plants need during flowering.
- PK 13/14 (1L): fertilizer to fatten the flowers by providing the phosphorus (13%) and potassium (14%) they require.
Elite 91 CalMag
This product has revolutionized crops, so it could not be missing from the best marijuana fertilizers of 2024. Elite 91 CalMag provides nitrogen, calcium, magnesium, and iron; allowing for the correction of deficiencies of these elements, increasing production, and achieving the greatest possible growth of the plant.
Elite 91 CalMag
It is compatible with hydroponic, soil, and coco crops. Additionally, it can be used together with any other quality fertilizer. It should be applied 2 to 3 times per week until root flushing arrives. Depending on the method of use, the dosage may vary.
To use it on cuttings, moisten the jiffies or rock wool in a solution of 0.5-2 ml per 4L. It is a perfect ally to stimulate roots and minimize stress.
Cannabiogen Delta 9
The flower stimulator par excellence. It provides a large amount of nutrients and other elements to achieve heavy buds and intense aromas that do not go unnoticed. All this, while helping the plant’s photosynthetic apparatus and activating its metabolism.
Delta 9 by Cannabiogen is applied only 3 times during flowering. It is important to read the manufacturer’s instructions, as it is not used the same way in a pot with soil as in hydroponics. In general, the dose is 5-6 ml per liter of water.
These are the best flowering fertilizers of 2025 due to their incredible results proven by expert growers. However, you can find a very wide range of products for cultivation on the web.
Delta 9 Cannabiogen
Top Candy
Top Candy by Top Crop is an additive used in the flowering phase and provides sugars to your plants to increase the weight, density, and aroma of your buds. A 100% organic carbohydrate supply to make life easy for your plants.
This product contains only 100% organic ingredients of the highest quality that have been certified as suitable for use in organic farming according to European regulations. It can be used in soil and coco crops, complementing flowering fertilizers, such as Top Bloom or SuperGuano.
Top Candy
Top Bud
Top Bud by Top Crop is a fertilizer to improve the final phase of flowering of our marijuana plants, obtaining greater results in the harvest, whether we grow indoors or outdoors.
Its NPK formula is specifically designed to fatten the buds, free of nitrates and with a high content of phosphorus, potassium, and essential amino acids. These compounds stimulate production and favor a notable increase in the size of the flowers, from the highest parts to the lower areas of the plant.
