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[Food For Thought] Nutrient Ratios & Relationships (Part 3 of 3)

[Food For Thought] Nutrient Ratios & Relationships (Part 3 of 3)

Alex Grady

Getting your NPK dosage right is about more than just your nutrient strength. It's also about your nutrient ratio.

This is part 3 of a 3 part series into plant nutrition. Here you'll find out about nutrient ratios and relationships.

NPK ratio

Plants need N, P, and K.

BUT the amount of each varies, depending on your stage of growth (and other factors).

That's why you have specific 'grow', 'bloom' and 'baby' formulas.

Grow Nutrients: are high in N & P

Bloom nutrient: are high in P & K

'Baby' plant nutrients: are very high in N and a bit higher in K than 'grow' nutrients

Coco nutrients don't have 'grow' and 'bloom' variants. Why? Coco likes to hang onto Nitrogen, but release Potassium, so coco feeds are different.

Grow and Bloom

Using Boosters and Additives

When you use boosters and additives, you're not just adding more nutreints. You're also changing your nutrient ratios.

For example:

PK boosters are high in Phosphorus (P) and Potassium (K).

Add them to your feed, and you'll widen the N:PK gap.

That's why we recommend adding a PK booster from week 4 of flowering. At this time, vertical growth stops, so they don't need as much Nitrogen. Plants also start forming their initial flowers - a bit of extra P & K ramps this up!

What's in my reservoir?

When mixing nutrients and boosters, it takes some work to calculate your new NPK ratio!

For each nutrient and booster, you will need to:

  • Find out the NPK ratio
  • Calculate the dilution factor
  • Nutrient concentration / dilution factor = % in nutrient solution

We'll show you how to do it with SHOGUN Samurai Hydro Bloom at 4ml/L dilution rate

Nutrient Relationships

Find NPK ratio

Your NPK ratio should be displayed somewhere on your bottle.

SHOGUN Samurai HydroBloom has an NPK ratio of 4.13 / 3.46 / 6

Get Dilution Factor

There are 3 steps:

1. swap dilution rate:
1L / 4ml

2. covert L to ml ( L x 1000):
1000ml / 4ml

3. Do the calculation:
1000ml / 4ml = 250 dilution factor

Calculate NPK in solution

Nitrogen / 240
4.13 / 250 = 0.01652

Phosphorus / 250
3.46 / 250 =0.01384

Potassium / 250
6 / 250 = 0.02400

NPK in solution: 0.01652 / 0.01384 / 0.02400

Repeat that process with every nutrient and additive you're using.

We also did if for SHOGUN PK Warrior and got 0 / 0.00450 / 0.00900

Add the two together:

SHOGUN PK Warrior: 0 / 0.00450 / 0.00900
SHOGUN HydroGrow: 0.01652 / 0.01384 / 0.02400

You get: 0.01652 / 0.01834 / 0.03300

By adding PK warrior, you now have almost twice as much potassium as you do nitrogen.

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