Grotek Blossom Blaster – 2.5 Kg

Grotek Blossom Blaster is a concentrated phosphorus and potassium supplement formulated to support the transition into flowering. It delivers available phosphorus to strengthen root development and fuel blooming, while potassium helps transport the sugars produced during photosynthesis. The 2.5 kg bag (SKU GTBB25G) provides enough product for large-scale or multi-cycle use and works in every growing medium alongside any base nutrient line.

Grotek Blossom Blaster Specifications

Specification	Value
Brand	Grotek
SKU	GTBB25G
Pack Size	2.5 kg (approx. 5.5 lb product weight)
Shipped Weight	6.01 lb
Form	Soluble powder
Primary Nutrients	Phosphorus (P), Potassium (K)
Application Stage	Early bloom — weeks 1 through 3
Application Frequency	Twice during first 3 weeks of flowering
Compatible Media	All growing mediums (soil, coco, hydro, rockwool)
Foliar Application	Not recommended — do not use as a foliar spray

Why Choose Grotek Blossom Blaster

Blossom Blaster concentrates on the nutrient window that matters most at the onset of flowering: phosphorus for cell energy and root support, and potassium to move photosynthetically produced sugars to developing flowers and fruit. Rather than adding inputs across the entire flowering cycle, this product is applied twice in the first three weeks — a focused approach that avoids nutrient excess in mid-to-late bloom.

• Available phosphorus for root and flower development. Phosphorus supplied in a readily available form supports root system integrity and powers the initial burst of floral development when sites are first forming.
• Potassium for sugar transport. Potassium is directly involved in moving sugars produced by photosynthesis through the plant, helping fill out developing fruit and flowers.
• Works in every growing medium. Whether you run soil, coco coir, rockwool, or a recirculating hydroponic system, Blossom Blaster integrates without changing your existing medium setup.
• Compatible with all base nutrients. No need to re-formulate your feed program — Blossom Blaster is designed to supplement, not replace, your base nutrient line.
• 2.5 kg bulk size for larger operations. The GTBB25G bag reduces per-cycle cost compared to smaller sizes and is well suited for commercial or multi-light gardens where consistency across multiple runs matters.

Best Uses for Grotek Blossom Blaster

Blossom Blaster targets the early bloom phase and is best suited to situations where a grower wants a dedicated P-K push at flower set without committing to a high-P base formula for the full cycle.

• Indoor flowering crops in hydroponic systems. NFT, DWC, and recirculating drain-to-waste systems benefit from a soluble powder that goes fully into solution without leaving residue.
• Coco coir and soilless media. Because Blossom Blaster is effective in all growing mediums, coco growers can integrate it directly into their reservoir alongside calcium-magnesium supplements and base A/B nutrients.
• Soil and amended beds. Top-dress or water-in applications during the first weeks after flipping to 12/12 can help signal and support the transition to flower.
• Multi-cycle commercial rooms. The 2.5 kg bulk bag is sized for operations running multiple harvests per year where consistency across each batch is a priority. Pair it with a root-focused additive like Advanced Nutrients Tarantula early in the cycle if root health is a concern going into bloom.
• Fruiting crops beyond cannabis. Phosphorus and potassium supplementation at flower set applies to tomatoes, peppers, cucumbers, and other fruiting plants grown under artificial or greenhouse conditions.

Compatibility

Grotek Blossom Blaster is compatible with all base nutrient programs, including two-part and three-part systems from any manufacturer. Because it is a soluble powder concentrate, it must be mixed fresh into your reservoir or feed water each time — do not pre-mix and store, and do not add it to an existing nutrient solution that has already been prepared.

It is effective across all common growing mediums: mineral soil, coco coir, peat-based mixes, rockwool, clay pebbles, and recirculating water-culture systems. No medium-specific compatibility issues are documented in the manufacturer data.

Blossom Blaster is not approved for foliar application — apply only as a root-zone drench or reservoir addition. If your feeding program already includes a high-phosphorus late-bloom booster, review total P load to avoid over-application. For growers managing a complete nutrient stack, consider how Blossom Blaster fits alongside other additives in the same L1 category, such as Earth Juice Hi-Brix Molasses, which provides a carbohydrate source to complement the sugar-transport role of potassium in this formula.

Dosing Guidelines

Grotek Blossom Blaster is applied twice during the first three weeks of the flowering phase. The manufacturer description specifies this two-application window at bloom onset; no specific per-gallon dose rate is published in the available supplier documentation for this product. Consult the Grotek feeding chart at grotek.com for current dosing rates by crop type.

General handling guidelines from the manufacturer:

• Always use fresh product — do not use product that has been left dissolved in water.
• Do not add Blossom Blaster to an already-prepared nutrient solution; mix it into fresh water first, then add other nutrient components.
• Do not apply as a foliar spray — root-zone application only.
• Measure accurately using a calibrated scale or measuring equipment appropriate for dry soluble powders.

Sources & Further Reading