simonkay
- 301
- 63
Apologies if this has been covered.
I'm trying to find parameters for PPMs+NPK ratios of nutrients all growers can follow easy as there's too many different grow charts with conflicting information.
The pic w/ green writing is Harley Smiths recommend fertilizer limits for cannabis. He recommends 1:1.2 N:K ratio for veg & 1:1.5 flower. He insists 80ppm is the limit for P and that even 20 PPMs in early veg is sufficient for root growth.
It is stated 4:2:1 ratio for K:C:Mg is recommended for LEDs (less Mg for older lamps) and that too much C or Mg can be antagonistic to K uptake.
Eg. GH aggressive feed recommends in early veg
150 N so with Harley's 1:1.2 N:K =
180K
50ish P
90C
45Mg (assuming you use LEDs)
The 2nd spanner is knowing about absorption rates (pic enclosed) so generally you only get about 44% of p2O5 and about 83% of K2O
So the question is should you roughly double your P numbers and give your K a 20% boost all the time or have manufacturers accounted for this. It is important to get calcium and potassium ratios correct for maximum uptake late flower as high vpd can slow K absorbing so I feel like it's a common reason ppl don't hit the yields. (Esp me)
It's recommended to front end load P, i.e. give more late veg early flower then reduce @mid flower while boosting K ratio, which is usually done by reducing N & then doing 1:1.5 N:K ratio.
The chart showing when to boost or drop NPK is considered fairly accurate so it comes down to timing & hitting the limits your plants allow.
We all have our different mediums & styles but surely the ratios and limits don't change too much right?
I've generally seen my plants top out @ 240ppms N in my environment in soil & got toxic dark green with genetics I have (which play a huge part in EC + PPM limits) so im seeing better results around 200N late veg. Which should give me a good baseline for the above minerals.
Id love to know what you guys do in terms of maintaining NPK ratios & what ppm limits you have for any of those minerals
I normally run double what the below GH chart recommends but I also use humics, microbes for added chelation then water once or twice in between to bring PPMs back down.
I'm trying to find parameters for PPMs+NPK ratios of nutrients all growers can follow easy as there's too many different grow charts with conflicting information.
The pic w/ green writing is Harley Smiths recommend fertilizer limits for cannabis. He recommends 1:1.2 N:K ratio for veg & 1:1.5 flower. He insists 80ppm is the limit for P and that even 20 PPMs in early veg is sufficient for root growth.
It is stated 4:2:1 ratio for K:C:Mg is recommended for LEDs (less Mg for older lamps) and that too much C or Mg can be antagonistic to K uptake.
Eg. GH aggressive feed recommends in early veg
150 N so with Harley's 1:1.2 N:K =
180K
50ish P
90C
45Mg (assuming you use LEDs)
The 2nd spanner is knowing about absorption rates (pic enclosed) so generally you only get about 44% of p2O5 and about 83% of K2O
So the question is should you roughly double your P numbers and give your K a 20% boost all the time or have manufacturers accounted for this. It is important to get calcium and potassium ratios correct for maximum uptake late flower as high vpd can slow K absorbing so I feel like it's a common reason ppl don't hit the yields. (Esp me)
It's recommended to front end load P, i.e. give more late veg early flower then reduce @mid flower while boosting K ratio, which is usually done by reducing N & then doing 1:1.5 N:K ratio.
The chart showing when to boost or drop NPK is considered fairly accurate so it comes down to timing & hitting the limits your plants allow.
We all have our different mediums & styles but surely the ratios and limits don't change too much right?
I've generally seen my plants top out @ 240ppms N in my environment in soil & got toxic dark green with genetics I have (which play a huge part in EC + PPM limits) so im seeing better results around 200N late veg. Which should give me a good baseline for the above minerals.
Id love to know what you guys do in terms of maintaining NPK ratios & what ppm limits you have for any of those minerals
I normally run double what the below GH chart recommends but I also use humics, microbes for added chelation then water once or twice in between to bring PPMs back down.
