FloraFlex - Bulky B Early Bloom Ripener

Bulky B is FloraFlex's bloom booster for the phase where your flowers put on volume. It is sold as a PK booster, and that word hides what is actually in it: this is first of all a potassium product, with sulphur as the second largest entry on the label.

Look at the ratio, not at the letters

FloraFlex's guaranteed analysis for Bulky B reads: 14% phosphate as P2O5, 43% potash as K2O, 11% sulphur and 1% magnesium, plus a trace of molybdenum.

Put those two headline figures side by side and the ratio is roughly one to three in potassium's favour. That is a very different product from a PK in which the two balance each other, and it is precisely the reverse of Full Tilt, the ripener this line finishes with.

That difference is not a detail but the reason FloraFlex run two of them. Potassium is the element a plant uses for water management, for moving sugars to wherever they are stored, and for the firmness of the tissue around them. That is the work of the phase where flowers gain volume. Phosphorus has its turn afterwards.

The sulphur is the second figure that counts

11% sulphur is unusually high for this shelf. Sulphur is a macronutrient, not a trace element: a plant needs roughly as much of it as of magnesium, and far more than of iron or zinc.

It is a building block of proteins and of some of the sulphur-bearing compounds that shape how a harvest smells. Most bloom boosters do not list it, because a bottle like that is sold mainly as phosphorus and potassium. Here it is on the label, and with 1% magnesium alongside it this is not a bare PK but a more broadly balanced bloom feed.

Oxide or element: where these numbers come from

Note how FloraFlex write it down. They give P2O5 and K2O, so the oxide form, as is standard on American and European fertiliser labels. Those are not percentages of phosphorus and potassium.

P2O5 is 43.6% phosphorus and K2O is 83.0% potassium. Converted, Bulky B therefore supplies roughly 6.1% phosphorus and 35.7% potassium. Read the oxide figures as elements and you think you are buying more than twice the phosphorus that is in the bag. Our own page used to do exactly that; it now carries the figures in the form FloraFlex publish them.

Using a powder

Bulky B is a water-soluble powder rather than a liquid, and that changes two things about your routine.

The first is the order. Add Bulky B only once your B1 and B2 base feed has fully dissolved. The second is that dissolving has a ceiling: FloraFlex state that at room temperature Bulky B goes into solution up to around 1.5 lb per gallon. They add explicitly that you should confirm everything has genuinely dissolved, and check your EC, before it reaches the plants.

With a powder that is not a redundant warning. Whatever fails to dissolve goes into your lines as a grain or settles at the bottom of the reservoir, and either way your crop gets something other than what you measured out. Pre-dissolve it in a little water, stir it through, and strain your stock solution if you run a drip system.

The dose, and why there is no single number here

FloraFlex publish no fixed dose for Bulky B at all. They give feeding schedules per gallon, varying by week and by programme strength, plus a calculator. That is deliberate: this product lives inside a schedule rather than on a one-line label.

So we put no figure here that we cannot stand behind. Take the FloraFlex schedule that matches your programme and read the column for the week you are in. What is fixed: you use it during the phase where the flowers build volume, and Full Tilt takes over for the last two weeks.

Available sizes

Technical Specifications:

• Type: water-soluble powder, bloom stimulator for the bulking phase
• Manufacturer: FloraFlex
• Guaranteed analysis: P2O5 14%, K2O 43%, sulphur 11%, magnesium 1%, plus a trace of molybdenum
• Converted to elements: roughly 6.1% phosphorus and 35.7% potassium
• Ratio: around one part phosphate to three parts potash
• Dose: per FloraFlex's feeding schedule, not published as a fixed figure
• Order: add once B1 and B2 have fully dissolved
• Solubility: up to around 1.5 lb per gallon at room temperature
• Period: the bulking phase of bloom, before Full Tilt
• Check: full dissolution and EC before watering

Frequently asked questions

Is this a PK booster?
In name, yes, but the ratio is about one part phosphate to three parts potash. It is mainly a potassium product, with 11% sulphur alongside.

Why is there no dose in grams or millilitres?
Because FloraFlex publish none. They give weekly feeding schedules and a calculator, and those are the source.

What is the difference with Full Tilt?
Full Tilt is the ripener for the last two weeks and leans the other way, at P2O5 47% against K2O 35%. Bulky B comes before it.

Is 14% phosphorus a lot?
It is not 14% phosphorus. It is 14% P2O5, which works out at roughly 6.1% phosphorus.

Where do I dissolve it?
In your feed water, once B1 and B2 have fully dissolved. Confirm everything is genuinely in solution and check your EC before watering.