FoxFarm Open Sesame 5-45-19 — High-Phosphorus Early Flowering Nutrient
Best for: Growers transitioning to the flowering stage who want a reliable phosphorus boost without overcomplicating their feed schedule
Our thoughts
Open Sesame does exactly what it says — it triggers the flowering transition properly. The NPK ratio is spot-on for early bloom initiation, and it works cleanly in hydro, soil, or containers. If you're running the FoxFarm sequence, this is the sensible starting point. One growers come back for because it performs.
FoxFarm Open Sesame is a water-soluble phosphorus-rich fertiliser formulated specifically for the early weeks of flowering. With an NPK ratio of 5-45-19, it delivers a heavy phosphorus hit right when plants need it most — around weeks five to six of the growing cycle — to initiate robust reproductive development and lay the groundwork for heavy flowering later on. Simple, reliable, and designed to work across hydro, soil, and container setups.
How it compares
Open Sesame sits in the proven mid-market segment of early flowering nutrients.
- Higher phosphorus concentration than balanced all-purpose feeds
- Part of a sequential three-product system (Open Sesame → Beastie Bloomz → Cha Ching), or works standalone
- Mineral-based formula with kelp and chelated micros for clean uptake
- Significantly more affordable than premium synthetic brands, same functional reliability
You're getting a purpose-built early-bloom formula that does the job without the premium price tag.
Usage guidance
Open Sesame is designed to be used starting around week five or six of the growing cycle, when plants begin the flowering transition.
Hydroponic systems
Mix 1 teaspoon (6g) per gallon (4 litres) of reservoir water. Feed every other watering. Flush the reservoir every two weeks to prevent salt buildup.
Soil and container growing
Mix 1/2 to 1 teaspoon (3–6g) per gallon (4 litres) of water. Feed once weekly. Start with the lower dose and adjust upwards based on plant response.
Feeding sequence (FoxFarm system)
Week 5–6: Open Sesame (early flowering trigger). Week 6–7: Switch to Beastie Bloomz (mid-to-late bloom support). Week 8+: Finish with Cha Ching (late-stage maturation). You can also run Open Sesame as a standalone early-bloom booster.
Key tip
Always dissolve in fresh water and mix thoroughly before feeding. This ensures even nutrient distribution and prevents nutrient lockout.
Technical specifications
- NPK ratio: 5-45-19
- Format: Water-soluble powder concentrate
- Primary nutrient focus: Phosphorus (45%)
- Hydroponic dosage: 1 tsp (6g) per gallon (4L) of water
- Soil dosage: 1/2 to 1 tsp (3–6g) per gallon (4L) of water
- Application window: Week 5–6 of growing cycle, every other watering (hydro) or weekly (soil)
- Key ingredients: Ammonium phosphate, monopotassium phosphate, potassium sulphate, kelp extract, chelated iron, zinc, manganese
- pH-balanced: Yes
- Container sizes available: 6 oz, 1 lb, 2 lb, 15 lb
Who this is for
- Hydroponic growers transitioning plants into the flowering phase
- Container and soil growers seeking a reliable phosphorus-driven early bloom trigger
- Anyone running the full FoxFarm nutrient sequence
- Growers who want straightforward feeding without guessing dosages or compatibility
- First-time flowering growers who need confidence in their nutrient timing
Particularly suited to growers familiar with water-soluble nutrients, or those stepping up from basic feeds and wanting a proven early-flowering system.
Our take
This is a proper early-flowering nutrient that earns its place in the schedule. The phosphorus ratio is aggressive enough to trigger the transition without overfeed risk, and it dissolves cleanly in any water type. FoxFarm's been making this since 1984 — they know what works.
If you're starting the flowering phase and want reliable results without the premium price, worth picking up. Does exactly what it should, week in, week out.
