Best NPK ratios for flowering

I'm not there yet, but I'm trying to come up with optimal NPK ratios to feed my plants during flower.

Right now I'm using a 7 3 3 granular fertilizer, the seed starting mix kind of forced my hand. I'm planning to augment that with the 4 4 8 sister fertilizer that PROMIX sells. And btw I really like and appreciate these granular fertilizers, they won't go bad anytime soon and one tbsp. of pellets whisked into a cup of water makes PLENTY of food.

If I was to mix those two fertilizers together I'd get an NPK ratio of [5.5 - 3.5 - 5.5] pretty balanced, right? I could probably get by feeding my plants this through veg. But then comes flower. I'm considering adding Gaia Green Power Bloom to the mix (is it water soluble?), it has an NPK of [2 - 8 - 4]. If I was to add that to the [4 - 4 - 8] fertilizer, I'd get an NPK of [3 - 6 - 6]. I should think this is my best option for flowering, or is the nitrogen content still a little too high?

As an aside, I could also add the [5.5 - 3.5 - 5.5] to the [2 - 8 - 4] to get closer nutrient ratios of [3.75 - 5.75 - 4.75] but I'm unsure of when or how to apply this one effectively.

Keep in mind that the N-P-K ratio (in the US at least) is NOT percentages of the elements, but the oxides for P and K (P2O5, K2O)

E.g. a 10-10-10 NPK label actually has

N%: 10
P%: 4.4
K%: 8.3

or 10-4-8 elemental NPK

Not exactly the 1:1:1 NPK many assume

Billy the Mountain said:

Keep in mind that the N-P-K ratio (in the US at least) is NOT percentages of the elements, but the oxides for P and K (P2O5, K2O)

E.g. a 10-10-10 NPK label actually has

N%: 10
P%: 4.4
K%: 8.3

or 10-4-8 elemental NPK

Not exactly the 1:1:1 NPK many assume

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I'm not sure I follow. Are you saying I can't trust the NPK ratios of the products I'm buying? How do I then properly discern the level of the nutrients in my fertilizer?

It's a moving target. You can plan, but there's no guarantee that it'll work, especially in flower. There's a certain amount of fly by the seat of your pants that has to go on. Different phenos, different strains, different sizes, and your environmental conditions all change what plants may want for nutrients.

bobj1598 said:

I'm not sure I follow. Are you saying I can't trust the NPK ratios of the products I'm buying? How do I then properly discern the level of the nutrients in my fertilizer?

Click to expand...

Not at all, you can safely ignore my elemental babbling

The actual ratio you choose is probably not in the top ten of factors affecting your final results

Use what you have, mixing is fine, just focus on growing a healthy plant

Lucas formula in ppm is

100n/100p/200k/60mg