Canna PK 13/14 - Concentrated Phosphorus and Potassium Flowering Booster
Best for: Growers in the flowering stage who want a short, sharp PK boost to support fruit and flower development.
Our thoughts
PK boosters get overused more often than they get underused - this one's designed to go in for one week only, which keeps it simple and stops you accidentally overdoing the phosphorus and potassium. Straightforward to dose, and it works with whatever base feed you're already running.
Canna PK 13/14 is a high-grade concentrate of phosphorus and potassium, the two macro-nutrients most directly tied to flower and fruit development in the generative stage of a plant's growth. Phosphorus plays a key role in energy transfer and cell formation in flowers, while potassium is essential for moving water and nutrients through the plant and for the sugar production that fuels flower development. CANNA's production process combines both elements in high concentrations, so they're quickly and directly available to the plant.
It's designed to be used with any growing medium - soil, coco, recirculating hydro or run-to-waste systems - and for both indoor and outdoor growing, which makes it a flexible add-on rather than a system-specific product.
How it compares
PK boosters vary in concentration, dosing simplicity, and how they're intended to be layered on top of a base feed.
- Advanced Nutrients' Big Bud takes a similar late-flower boosting role but is formulated as part of Advanced Nutrients' own wider feeding system
- House & Garden's Bud-XL focuses on cell division and flower size rather than a straight PK spike
- Aptus Super PK offers a comparably concentrated PK supplement aimed at growers who want a short, targeted application in the same way
PK 13/14's main selling point is simplicity: one short, defined dosing window rather than an ongoing addition through the whole flowering phase.
Usage guidance
Timing and duration matter more with PK boosters than with a standard base feed.
Dosage
Dissolve 15ml of concentrate per 10 litres of water (1:666) into a full nutrient tank.
Timing
Add it roughly three weeks before harvest, and use it for one week only (CANNA's own guidance caps it at 3-6 days within that window) - using it for longer risks a build-up of phosphate and potassium in the substrate.
Pairing
CANNA recommends combining it with CANNABOOST Accelerator, which supports the plant's metabolism and strengthens the effect of the PK boost.
Suitable systems
Works across soil, coco, recirculating and run-to-waste setups, so you don't need to adjust it for your specific growing method.
Technical specifications
- Active elements: Phosphorus (P) and Potassium (K)
- Application window: One week, approx. 3 weeks before harvest
- Dilution rate: 15ml per 10L water (1:666)
- Suitable media: Soil, coco, recirculating hydro, run-to-waste
- Pack sizes: 250ml, 1L, 5L
- Bottle material: Polyethylene (PVC and cadmium free), recyclable
- Brand: CANNA
Who this is for
- Growers in flower who want a short, defined PK boost rather than an ongoing additive
- Anyone already running a CANNA feeding schedule and adding CANNABOOST alongside it
- Growers who prefer a simple one-week application window over guesswork on dosing duration
Best suited to growers who want a targeted late-flower boost without adding another product to their feed for the whole cycle.
Our take
It does one job, for one week, and does it well - there's not much more to say about a PK booster than that, and that's exactly the point of it.
Does exactly what it should, day in, day out - a sensible, low-cost addition once you're deep enough into flower to need it.
