Plagron Alga Bloom — Certified Organic Bloom Nutrient for Soil Growing
Best for: Organic soil growers wanting a single-part bloom nutrient that works with nature, not against it
Our thoughts
Alga Bloom is a proper organic nutrient that does the job without overcomplicating things. One-part application, certified organic, and it genuinely supports soil life rather than bypassing it. The algae extract tech actually speeds up nutrient availability, which matters when you're working with organic conversions. Good value for a certified product.
Plagron Alga Bloom is a certified organic base nutrient designed specifically for the flowering phase of soil-based growing. Built on algae extract technology and packed with amino acids, it delivers balanced nutrition whilst actively improving soil structure and microbial activity. This is organic nutrient that treats soil as a living system, not a delivery mechanism.
How it compares
Sits in the mid-range organic bloom category, competing directly with BioBizz and CANNA.
- More balanced phosphorus-potassium ratio than BioBizz Bio Bloom (3-2-5 vs 2-7-4)
- Certified organic like BioBizz, but with algae-extract acceleration — faster nutrient cycling in soil
- Single-part application, no complex mixing or additional boosters required
- Works soil-only, so not an option for hydro growers
- Established brand — 25+ years in production, proven track record
Usage guidance
Simple to use. One-part nutrient, no balancing act required.
Dosage
Add 4 ml per litre of water (1:250 ratio). Apply this solution every time you water during the flowering phase. That's it.
Timing
Start from week four of your growing cycle. Organic nutrients take roughly two weeks to convert through soil life, so patience matters here — this is not a quick-fix booster, it's a system nutrient.
Combine with Alga Grow
Use Alga Grow during the vegetative phase, then switch to Alga Bloom for flowering. Plagron designed these to work together across your entire cycle.
pH and EC
With natural substrates, you don't need to adjust pH or EC values. Soil life handles this automatically. The organic compounds and amino acids in Alga Bloom actually stimulate this process — one less thing to worry about.
Normal cloudiness
The solution may look cloudy once dissolved. This is the organic ingredients doing their job and natural bacterial processes starting. Perfectly normal, no impact on plants.
Technical specifications
- NPK ratio: 3-2-5
- Total nitrogen: 3.3% (organically bound)
- Phosphorus (P₂O₅): 2.3% (water-soluble)
- Potassium (K₂O): 5.4% (water-soluble)
- Key ingredients: Algae extract, amino acids (20+ varieties), beet vinasse, trace elements
- Trace elements included: Iron, boron, molybdenum, copper, manganese, zinc
- Certification: Control Union certified organic
- Recommended dosage: 4 ml per litre water
- Shelf life (unopened): 4 years
- Shelf life (opened): 6 months guaranteed
- Available sizes: 100 ml, 250 ml, 500 ml, 1 L, 5 L, 10 L, 20 L
- Suitable for: Soil and coir-based growing only — not for hydroponic systems
Who this is for
- Organic soil growers who want certified products and clean growing practices
- Soil-based indoor growers looking for a straightforward, single-part bloom nutrient
- Budget-conscious growers wanting mid-range organic quality without premium markup
- Growers who understand that organic nutrition takes patience but delivers better soil long-term
- Anyone already using Plagron Alga Grow who wants a matched system
Our take
This is a solid organic bloom nutrient that respects soil as a living thing, not a substrate to push past. The algae extract and amino acid blend actually speed up nutrient conversion, which addresses the main complaint about organic nutrients — waiting for soil life to do the work. You're getting certified quality at a reasonable price point, and it genuinely delivers results.
If you're running organic soil and want something reliable that won't stress the budget, worth picking up. Does exactly what a flowering nutrient should do, and leaves your soil better than you found it.
