Plant Magic Platinum PK 9-18 - Concentrated Bio-Stimulant Bloom Booster
Best for: growers in soil, coco or hydro who want a strong late-flower PK boost for heavier, more developed yields.
Our thoughts
This is Plant Magic's flagship PK booster, and the numbers back that up - 9% phosphorus pentoxide and 18% potassium oxide is a genuinely strong ratio. It's not just a raw PK hit either; the added sulphur and bio-stimulants are there to help plants actually use that phosphorus and potassium rather than just flooding the root zone with it. Dosed in small amounts, so a little bottle goes further than it looks.
Plant Magic Platinum PK 9-18 is a highly concentrated flowering booster combining phosphorus and potassium with a blend of bio-stimulants and sulphur, aimed at bigger plants and heavier yields. Its NPK figures come out at roughly 9% P2O5 (around 3.9% elemental P) and 18% K2O (around 14.9% elemental K), with sulphur trioxide included to speed up photosynthesis and phosphorus uptake while supporting protein and amino acid production. The bio-stimulants in the mix feed beneficial microbes and fungi around the root zone, helping break nutrients down into a form roots can actually take up.
It's usable across soil, coco or full hydro systems, and because it's so concentrated, it's dosed in small amounts rather than by the capful - a little goes a long way.
How it compares
PK 9-18 sits at the higher-concentration end of the PK booster market, aimed at growers chasing a strong late-flower push.
- Compared with Canna PK 13/14, one of the best-known PK boosters, both deliver a strong phosphorus-potassium hit late in flower, with Platinum PK 9-18's added sulphur and bio-stimulant blend being a point of difference.
- Compared with House & Garden Bud-XL, another concentrated bloom booster, the two compete on similar ground for growers wanting maximum bud development.
- Compared with Plant Magic's own organic Oldtimer PK 4-8, Platinum PK 9-18 delivers a substantially stronger raw PK figure, at the cost of not being certified organic.
If raw PK strength is what you're after, this sits comfortably among the stronger boosters on the market.
Usage guidance
Platinum PK 9-18 is dosed in small amounts given its concentration.
Dosing
Use at a dilution rate of roughly 0.2-0.5ml per litre of nutrient solution - don't be tempted to overdose given how concentrated it is.
Timing
Introduce once plants are established in flower, running it through the bulk of the bloom phase for weight and density.
System suitability
Suitable for soil, coco or full hydroponic systems without needing to adjust the base dosing rate significantly.
Technical specifications
- NPK figures: approx. 9% P2O5 (approx. 3.9% P), 18% K2O (approx. 14.9% K)
- Total nitrogen: approx. 2.6%
- Sulphur trioxide: approx. 28% SO3
- Additional ingredients: bio-stimulant blend for microbial/fungal root support
- Dosage: approx. 0.2-0.5ml per litre
- Suitable media: soil, coco, hydroponics
- Sizes available: 500ml and 1 litre
- Brand: Plant Magic
Who this is for
- Growers wanting a strong late-flower PK push across any medium
- Anyone already running Plant Magic Ignition earlier in flower and looking for the follow-up product
- Experienced growers comfortable dosing a highly concentrated additive accurately
- Growers chasing heavier, denser flowers at the end of the cycle
Our take
A genuinely strong PK booster on paper, and the bio-stimulant and sulphur additions give it an edge over a straight mineral PK feed.
Worth picking up if you're already running Plant Magic's range and want a proper late-flower push to finish the job.
