FloraFlex - B2 Bloom/Flower Part 2

B2 is the second half of FloraFlex's bloom feed. The striking thing about its analysis is not what is on it but what is missing: there is no nitrogen in it. None.

All your nitrogen in bloom comes from B1

B2's guaranteed analysis has four lines: 28% phosphate as P2O5, 18% potash as K2O, 7% magnesium and 11% sulphur. There is no line for nitrogen, because there is none in it.

That is a design decision with consequences for your schedule. In a two-part bloom feed where one part carries all the nitrogen and the other carries none, you set the nitrogen ratio through the dosing ratio between the two. Give more B2 and less B1 and you shift automatically toward less nitrogen and more phosphorus, without replacing anything.

That is exactly what most growers want in the final weeks, and on this line you do not have to buy a separate product for it. It is already built into how the two parts relate.

The other side of the same coin is on the B1 page: cut B1 back and your calcium comes down with it, because that sits in B1 and not here.

Two salts, and what they bring

FloraFlex name the source: monopotassium phosphate and magnesium sulfate. That accounts for all four lines on the label precisely. The monopotassium phosphate supplies the phosphorus and part of the potassium, the magnesium sulfate supplies the magnesium and the sulphur.

That 11% sulphur is higher than you see on most bloom feeds, and so is 7% magnesium. Both follow directly from choosing magnesium sulfate as the carrier: you get the sulphur along with it because it is a sulfate. Here that is not ballast but usable nutrition, since sulphur is a macronutrient a plant needs in serious quantity.

Oxide or element

The phosphorus and potassium are on the label as P2O5 and K2O, the magnesium and sulphur as elements. That is standard on a guaranteed analysis and it is where comparisons between brands go wrong.

Converted, B2 supplies roughly 12.2% phosphorus and 14.9% potassium. Our own page used to say 28% phosphorus and 18% potassium; those were the oxide values with the wrong label on them, and they have been corrected.

In use

Add B2 once B1 has fully dissolved, throughout the flowering stage. For source water FloraFlex hold an EC of 0.2 to 0.3, with 0.7 as the upper limit.

Check that the powder really is in solution and measure your EC before watering. At lower dosages B1 and B2 can, per FloraFlex, also serve as a base alongside other additives. They publish no fixed number of grams as a single figure; it lives in their weekly schedules by programme.

Available sizes

Technical Specifications:

• Type: water-soluble powder, part 2 of the two-part bloom feed
• Manufacturer: FloraFlex
• Guaranteed analysis: P2O5 28%, K2O 18%, magnesium 7%, sulphur 11%
• Nitrogen: none
• Converted to elements: roughly 12.2% phosphorus and 14.9% potassium
• Derived from: monopotassium phosphate and magnesium sulfate
• Order: add once B1 has dissolved
• EC of your source water: 0.2 to 0.3 ideal, 0.7 maximum
• Period: the whole flowering stage
• Dose: per FloraFlex's feeding schedule

Frequently asked questions

Is there really no nitrogen in it?
No. FloraFlex's analysis has no nitrogen line for B2; all the nitrogen in bloom comes from B1.

How do I lower my nitrogen in the final weeks?
By shifting the ratio between B1 and B2. More B2 against less B1 means less nitrogen and relatively more phosphorus.

Isn't 28% phosphorus extreme?
It is 28% P2O5, which works out at roughly 12.2% phosphorus.

Why is there so much sulphur in it?
Because the magnesium is delivered as magnesium sulfate. The sulphur comes with it and is usable nutrition.

In what order do I mix?
B1 first, and B2 only once B1 has fully dissolved.