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During the flowering stage, cannabis plants need specific nutrients like phosphorus and potassium to develop large, dense, and resinous buds. Using a specialized fertiliser ensures a heavy harvest with buds full of aroma, flavor, and outstanding potency. Below, we’ve compiled a complete list of the best cannabis fertilisers for flowering in 2025 available in our store, so you can get the maximum yield from your grow.
What is a flowering fertiliser
A fertiliser is a substance used to provide essential nutrients to plants and improve their growth and development. It usually contains nitrogen (N), phosphorus (P), and potassium (K), along with other key micronutrients like calcium, magnesium, iron, and zinc, which are also crucial for plant metabolism and health.
It’s highly recommended to use a fertiliser specifically designed for the cannabis flowering stage. This phase has very particular nutrient requirements that general-purpose fertilisers or those meant for vegetative growth cannot meet. Flowering is when the plant develops its buds, which are the most valuable part for growers.
During flowering, cannabis plants have different nutritional needs. They lower their demand for nitrogen (N), essential in vegetative growth, and increase their need for phosphorus (P) and potassium (K).
- Phosphorus helps produce larger, denser, and more resinous flowers.
- Potassium improves bud formation and ripening, boosting their size and resilience.
Flowering fertilisers provide the ideal NPK ratios and other micronutrients (calcium, magnesium, sulfur) that promote healthy, abundant flowering.
What can you achieve with flowering fertilisers
- Bigger, denser buds. With the right amounts of phosphorus and potassium, buds grow larger, heavier, and more compact.
- More resin and trichomes. Flowering is when the plant produces the most trichomes, the glands where cannabinoids and terpenes are concentrated. Fertilisers enriched with sugars or humic acids stimulate trichome production, significantly enhancing aroma and potency.
- Better flavor. Organic fertilisers or those enriched with natural sugars encourage terpene production, which defines the buds’ aroma and taste. A balanced nutrient profile also prevents salt buildup that could negatively affect the flavor profile.
- Even ripening. Fertilisers designed for the final flowering stage (ripening) help all buds reach peak maturity at the same time.
What are the best cannabis fertilisers for flowering
Among the best cannabis fertilisers for flowering available in our catalog, you’ll find the following options:
Flowering by Flower Power
Flowering by Flower Power is a powdered fertiliser made specifically for the cannabis flowering phase. It contains 30% potassium, 15% nitrogen, and 6% phosphorus. Its fast-absorbing formula allows plants to quickly benefit, encouraging the development of larger, higher-quality flowers. This product works in any growing medium, including hydroponics, coco, or soil.
Bactobloom by Agrobacterias
Bactobloom by Agrobacterias is a soluble powdered flowering booster made from beneficial bacteria that enhance the root environment and improve nutrient absorption. These bacteria increase sugar production in plants, leading to larger, denser, and stickier buds. They also help reduce environmental stress and protect against fungi and pests. Perfect for pot-based grows.
Floración Boom by Boom Nutrients
Floración Boom by Boom Nutrients is a single-component fertiliser created to meet cannabis plants’ nutritional needs during flowering, both in intensive outdoor and indoor grows. With a balanced NPK 5-7-10% formula, it helps plants produce thick, large, aromatic flowers without needing extra additives or bud enhancers.
This fertiliser is easily absorbed, allowing plants to take full advantage quickly. It’s recommended from the first week of flowering indoors and from the continuous appearance of pistils outdoors. Floración Boom comes in 1L and 5L formats.
Bloom by GB Nutrients
Bloom by GB Nutrients is a liquid bio-mineral fertiliser designed to feed cannabis plants during the flowering stage. With a balanced formula and optimal NPK levels (1-3-5%), it stimulates the development of more flowering sites. It also promotes the growth of abundant buds with higher resin production while improving density, flavor, and aroma. Apply Bloom twice a week from the beginning of flowering until the final flush, using 2–3 ml per liter of water.
Organic Bloom by Boom Nutrients
Organic Bloom by Boom Nutrients is a 100% plant-based liquid fertiliser that stands out thanks to two unique biomolecules in its formula: Fucoidan and Alginic acid, both extracted from seaweed.
- Fucoidan. Stimulates plant metabolism and enhances cell division, resulting in denser flowers. It also improves the plant’s ability to resist environmental stress and disease.
- Alginic acid. Improves water retention in the substrate, boosting root hydration and helping plants absorb essential nutrients for stronger flower development.
Bio Bloom by Biobizz
Bio Bloom by Biobizz is a 100% organic liquid fertiliser that provides cannabis plants with all the nutrients they need during flowering. With a balanced NPK ratio of 2-7-4, it’s enriched with enzymes and amino acids that stimulate abundant flowering and flavorful buds. It also contains trace elements and natural plant hormones that promote strong stems and vigorous flower development.
Bio Bloom can be used in soil and soilless substrates and applied from the start of flowering until harvest. Recommended dose is 2–4 ml per liter of water. Not suitable for irrigation systems as it can clog drippers and pipes. Available in 1L, 5L, 10L, and 20L sizes.
Delta Boom by Boom Nutrients
Delta Boom by Boom Nutrients is a powerful biostimulant formulated for the cannabis flowering stage. It’s enriched with seaweed extracts, carbohydrates, enzyme activators, vitamins, plant-based amino acids, macronutrients like nitrogen, potassium, phosphorus, calcium, and magnesium, plus essential micronutrients such as cobalt, zinc, molybdenum, manganese, sulfur, and boron.
Applying Delta Boom during flowering boosts THCA production, essential oils, and resin density, resulting in denser, stickier buds. It also strengthens natural plant defenses and improves nutrient uptake. Suitable for soil, coco, and hydroponic systems. For best results, use during the flowering phase following the product’s specific instructions.
BloomStimulator by Atami
BloomStimulator by Atami is a flowering booster that helps cannabis plants enter the flowering stage faster and more abundantly. Perfect for increasing bud density and size, it allows plants to produce more compact, resin-packed flowers.
The main advantage of BloomStimulator is that it accelerates the start of flowering and prolongs it, which leads to richer, heavier harvests. It not only increases yield but also improves terpene quality.
Highly concentrated, it must be diluted in water before use. Add 0.5–1 ml per liter of water and apply during irrigation starting from the first signs of flowering. Available in sizes from 100 ml to 5 liters.
Monster Bloom by Grotek
Monster Bloom by Grotek is a highly concentrated flowering enhancer designed to increase bud size and density. Its formula contains a high concentration of phosphorus and potassium (NPK 0-50-30), essential elements for protein and sugar synthesis. This accelerates the plant’s internal processes and strengthens cell walls and structures, resulting in bigger, more compact flowers.
For dosage and application, it’s recommended to add 0.3 grams of Monster Bloom per liter of irrigation water. Apply once a week during the bud-fattening phase, when flowers are already well-formed, usually from the 4th or 5th week of flowering depending on the strain. Do not exceed the recommended dosage, as its high concentration can cause over-fertilisation problems.
The formula of Monster Bloom contains high levels of phosphorus (50%) and potassium (30%), two essential nutrients for abundant, high-quality flowering. For best results, it’s recommended to combine with other products from the same line, such as Heavy Bud Pro, which provides an extra boost of sugars and further enhances bud density and compactness.
Big Boom PK 52-34 by Boom Nutrients
This Boom Nutrients fertiliser is designed to fatten cannabis buds, making it essential during the flowering stage. It has earned its spot on the 2025 list of the best cannabis fertilisers thanks to its extremely high phosphorus and potassium content.
To maximise results, it should be used together with a quality flowering fertiliser, an additional source of sugars or carbohydrates, a flowering stimulator, and enzymes to revitalise the roots.
Big Boom PK 52-34 is unique in that it offers three application methods depending on the grower’s experience. Note that the recommended doses must be diluted in 10 liters of water, unlike most cannabis fertilisers, which are dosed per liter.
Bloombastic by Atami
This all-round product is one of the best flowering fertilisers: it provides extra phosphorus and potassium as well as carbohydrates and sugars, leading to explosive flowering and resin-covered buds. Its reputation is global thanks to its outstanding results, which is why it remains on the 2025 list of the best cannabis fertilisers.
To use it properly, growers must follow the Atami Bloombastic feeding chart. Adding Bloombastic by Atami from the 4th week of flowering produces large, heavy buds. Nitrogen keeps the leaves intensely green, while sugars and carbohydrates promote resin production and improve flavor.
Apply during the last 4 to 6 weeks of flowering, combining it with base nutrients. Simply water 2–3 times per week, diluting 0.5–1 ml per liter of water.
Organic Bloom by BAC
Organic Bloom by BAC is a 100% natural organic fertiliser with a balanced NPK formula (5-2-5) plus additional ingredients such as alfalfa meal, sugar molasses, and stone meal. These components help plants produce premium-quality buds. The product comes with a detailed feeding chart from the manufacturer, specifying dosage and frequency. It can be combined with other flowering fertilisers, but growers should take care to avoid nutrient buildup. To prevent this, it’s recommended to water with plain water once a week to allow the soil to absorb all nutrients.
Organic Bloom is an eco-friendly and efficient option for growers seeking top-quality cannabis flowering. Available in 1L, 5L, and 10L formats.
Bloombastic Terra Box Atami
The Bloombastic Box Kit by Atami is a complete fertiliser set for soil-based cannabis cultivation. It includes products for all stages, from growth to flowering, ensuring plants receive the right nutrients at every phase.
The composition of these products is enriched with high levels of bio-minerals, particularly phosphorus and potassium, which are essential for abundant, high-quality flowering. Unlike other stimulators, it does not contain unassimilable substances like sodium or chlorine, ensuring safer and more effective nutrition.
- Terra Leaves. Fertiliser for the vegetative stage, promoting strong and healthy growth.
- Terra Max. Flowering fertiliser designed to produce dense, aromatic buds.
- Bloombastic. A cocktail of bio-minerals (NPK 0-14-15) and biostimulants that increase flower weight, aroma, and sugar content.
- ATA-Zyme. Improves substrate balance, breaks down organic matter, and keeps the root system healthy.
- ATA-Rootfast. Root stimulator.
Canna fertiliser kit
Components of the Canna Fertilizer Kit
For the vegetative growth stage:
- Terra Vega (1L): an organic-based product that ensures vigorous plant growth in a short period of time.
- Rhizotonic (250 ml): root stimulator that increases nutrient uptake, improving overall plant quality.
- Cannazym (250 ml): activates soil microorganisms that break down organic matter, converting it into sugars the plant can absorb.
For the flowering stage:
- Cannaboost Accelerator (250 ml): boosts chlorophyll formation and distributes energy throughout the plant, stimulating flowering.
- Terra Flores (1L): base fertilizer for soil that supplies all essential nutrients needed during flowering.
- PK 13/14 (1L): bud-enhancing fertilizer, providing the phosphorus (13%) and potassium (14%) required for optimal flower growth.
CalMag by Elite 91
This product has revolutionized cannabis cultivation and is a must-have among the best cannabis fertilizers of 2024. CalMag Elite 91 provides nitrogen, calcium, magnesium, and iron, helping to correct deficiencies, boost yields, and achieve maximum plant growth.
Compatible with hydroponic, soil, and coco cultivation, it can also be used alongside any other quality fertilizer. Apply 2–3 times per week until root flushing. Dosage may vary depending on usage instructions.
For cuttings, soak jiffies or rock wool in a solution of 0.5–2 ml per 4L of water. A perfect ally to stimulate roots and minimize stress.
Delta 9 by Cannabiogen
The ultimate flowering stimulator. Provides a rich supply of nutrients and other elements to achieve heavy buds with intense aromas while supporting the plant’s photosynthesis and metabolism.
Delta 9 by Cannabiogen is applied only three times during flowering. Follow the manufacturer’s instructions carefully, as application differs between soil pots and hydroponic systems. General dosage: 5–6 ml per liter of water.
These are among the best cannabis flowering fertilizers for 2025, backed by proven results from expert growers. You can also find a wide range of cultivation products on our website.
Top Candy
Top Candy by Top Crop is an additive used during the flowering stage, providing sugars to your plants to increase bud weight, density, and aroma. A 100% organic carbohydrate boost that makes life easier for your plants.
This product contains only premium 100% organic ingredients certified for use in organic cultivation according to European standards. It can be used in soil and coco grows, complementing flowering fertilizers like Top Bloom or SuperGuano.
Top Bud
Top Bud by Top Crop is a fertilizer designed to enhance the final flowering stage of cannabis plants, resulting in higher yields whether growing indoors or outdoors.
Its NPK formula is specifically designed to fatten buds, nitrate-free, and rich in phosphorus, potassium, and essential amino acids. These compounds stimulate production and significantly increase flower size from the top colas to the lower branches of the plant.
