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Fertilizer, NPK, requirements for Cannabis

rippedcb

New Member
Hi guys,
Really hoping someone can help me understand/learn Cannabis nutirent requirements. Possibly @MrSauga ; @farside05 @Emilya (and hoping you don't mind me tagging you) I'm new to the forum, but not a novice grower by any means, but always looking to improve my knowledge base. I've successfully used many multi part nutrients, but coming across Mega Crop (sorry Emilya) has made me wanting to learn more about what i'm feeding my plants/why/when. Now i know the basic info that's all over the web, such as higher need of N during veg and vise-versa for PK during flowering. But what i'm wanting to learn about is the specific ratios that i must stay within during different stages. There must be a max/min concentration of certain macros during certain stages/all stages? I've tried searching the net and have come across bits of info ie) I never want to exceed 150ppm of N, never to have ratio of N:K exceed 1:3.. but its all just broken information that i want to piece together. Is there a website/journal/study anyone can point me towards so i can learn this? I would really like to dive into using Mega Crop, it seemed so simplistic and great idea, but the more i read here and the more pictures i see of people posting of their plants on Mega Crop, its scaring me to take the plunge. Some plants are so horrific that i've never seen people keeping (never mind sharing photos of proudly) of plants like that. I'd be heartbroken if my plants ever look anything like them.

I tried (really really hard) to read and follow the MegaCrop thread and got up to page 29.. but there are still 160 pages to go and its mostly filler material. It took me a whole day to go thru 30 pages, i'll be scrolling thru that thread for the next 3 days. I wish there was a way to filter comments in threads by

Am i correct in doing my math if i assume (taking mega crop as an example 9-6-17) that for each 1000ppm there will be
232ppm of N
71ppm of P
360ppm of K

Using that as an example, how do i figure out how to encorporate a PK booster during flowering? Am i correct in assuming that i could lower the dosage of mega crop to 800ppm will bring down the numbers to
186ppm of N
57ppm of P
287ppm of K

so if i was to add 200ppm of 0-10-10 to this i'll end up with

186ppm of N
157ppm of P
389ppm of K -> still with in 1:3?
Is that correct way of going about this?

If i were to use 200ppm of SweetCandy as a PK booster 0-17-28 i'll end up with

186ppm of N
142ppm of P
477 ppm of K -> still within 1:3

Am i going about this the right way? any help or direction would be appreciated. I'm willing to put the time in and read if someone can guide where to look.

Thank you.
 

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MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
Hi Rip,
the simplest way is to use MC alone on your first grow. Start by using the calculator and adjust as the plant dictates. I wouldn't worry about any supplements for now since as you learn the product you'll also understand more about the supplements.

The best NPK ratio for growing cannabis is 2:1:3 and can be mucked around with such as 2:1:4. For the most part both of those will get you from seedling to harvest.
Depending on your environment you may need some calmag, don't worry too much about the PPM numbers if you plan on using MC only, which is my suggestion.

On the GLN website they have an Elemental calculator which shows how much of each element is going in based on the amount of MC being used, in PPM.

Tag me when you have a journal and I'll help you along.
 

Emilya

Member of the Month: Mar 2019 - Grow Journal of the Month: Jan 2020
I am presently being stifled, so all I can recommend is for you to read my current journal if you wish to hear my thoughts on MegaCrop... some seem to believe that I am putting out misinformation and dont want me commenting in other threads or I will be labeled a troll. At the risk of trolling you, I will let you and time decide.
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
Oof...
 

rippedcb

New Member
Thank you so much for replying @MrSauga I completely/truly understand that i can finish the grow from start to finish using MegaCrop only. It has everythign i need in it. I absolutely get that, However, i would like to learn how to encorporate PK boosters or learn how and when to be able to manipulate NPK numbers. I was hoping you could at least tell me if i was going about it the right way by my calculations? I have no issues figuring out dosages based on grams/ppm/ec and i know i'll have no issues completing a grow using MC only or any other nutes. But the idea is to learn and improve on my knowledge.

@Emilya I'm not looking for feedback regarding any specific products.. i was wanting to learn how to manipulate macros for cannabis while staying safe. Wanting to learn and expand. Thank you for replying. I'll definitely go thru our journals.
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
However, i would like to learn how to encorporate PK boosters or learn how and when to be able to manipulate NPK numbers. I was hoping you could at least tell me if i was going about it the right way by my calculations? I have no issues figuring out dosages based on grams/ppm/ec and i know i'll have no issues completing a grow using MC only or any other nutes. But the idea is to learn and improve on my knowledge.
There is no safe way to use the PK boosters until after the plant has hit flower week 2. After that the most you can go is 1g/gal. Doing it by the numbers I couldn't tell you as I don't do it that way. I know that it works once you have the MC dialed in correctly and have not overfed through veg. If you stay below 6g/gal of MC you can safely use 1g of Bud Explosion. You can do the same similar with SC but not both as it throws things way out of whack.
I'm going to send you a nute calculator spreadsheet that will help you get where you want to be. I know what you want and I think you find this tool quite handy.

Hang tite.
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
Great article, but I think if you run those numbers with MC you may have some issues. In order to get that high of a K value you would need to feed MC at 7.5g/gal during veg. The chart below shows around 300ppm and P around 150ppm.

If you look at the image below the chart you will see a screenshot of the MC elemental calculator at 7.5g/gal. It's obvious right away that MC can't get there alone. Anyhow thanks for the link :thumb:

1581463780732.png


1581463927441.png
 

rippedcb

New Member
Absolutely rediculous numbers for the finish, no? but does kinda makes sense if its only for the last week. if you don't care about burnt folliage? I would imagine that would fry the plant?

I'm playing around with the Calculator from you guys and having a blast. Its awesome and so handy.. exactly what i needed and now i'll be able to play around with numbers and fertilizers :D I'm sure i'll make mistakes, but as long as i learn and improve over time.
I'll be aiming for
N: 125ppm
P: 60
K: 225
till about the last 2 weeks and then push up P and K slowly keeping an eye out for lockouts.. I'll just increase sweetcandy (0-17-28) for the boost.
May i please have your guys' feedback on this? @MrSauga @farside05 @InTheShed Please?


1581465967256.png
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
I think you might run into some issues. What I don't like is the new formula for the Sweet Candy. They added P which makes no sense. The bag I have is 0-0-16 and works great with my v1 of MC.

Here's a pic again off the calculator at 5g... as close as I could get to your numbers.

1581466661019.png
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
So yes it is close and you may have some small issues at the end, but it's for science and I'm all for that :thumb:
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
The reason I show the calculator is to base how much grams per gallon you would use to get those numbers if using MC alone. Most of us know any higher than 6-6.5g/gal on most plants will lead to issues. Some plants will struggle to get to 6g and it's usually related to early overfeeding.

So we know at 5g per gallon is close to meeting you numbers in the end with some small changes and it means you would be well within the calculators doseage, albeit you have changed the NPK ratio which is what you were after all along.
:goodluck:
 

rippedcb

New Member
You feel Phosphorus at 60ppm is too high? reduce <50? due lockout concerns? or something else?
i was actually happy about the added P in Sweetcandy. I figured they did that so one wouldn't have the need to buy a PK booster. Now you get a PK booster along with the carbs and goodies. Seems like a good ratio as well.
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
Here's a good article to read.. a quick one and then you can decide what you want to do. I don't think there's anything wrong with your ratio... but most plants don't need much P in flower.

 

rippedcb

New Member
That was a good read, thanks for pointing me towards that. and i completely understand what you are getting at. I agree, but i'll play around a bit with PK my next grow trying to stay within limits :D
 

MrSauga

Photo of the Month: Sept 2018, Nov 2019 - Member of the Month: Feb, Dec 2019
That was a good read, thanks for pointing me towards that. and i completely understand what you are getting at. I agree, but i'll play around a bit with PK my next grow trying to stay within limits :D
Nothing wrong with that at all. We can show you the resources and the facts and after that it's up to the grower on what they want to do. I think you're going to have a lot of fun and that's a big part of growing anyhow.
 

farside05

Plant of the Month: Dec 2018, June 2019
You may want to REVIEW THIS and also the AN Study Results tab in the calculator spreadsheet and determine if adding loads of P or K is necessary.
 

farside05

Plant of the Month: Dec 2018, June 2019
Something else to keep in mind when comparing fertilizer N-P-K values with tissue sample results. P and K percentages shown on fertilizer packages are not the actual amount of P or K in the blend. The percentage of P on the package is the percentage of P2O5 (phosphorous pentoxide) and you need to multiply the percentage shown by .43 to get the actual amount of P in the fertilizer. Similarly, the K level percentage shown is actually the level of K2O ( potassium oxide) and must be multiplied by .83 to arrive at the actual amount of K supplied.
 

rippedcb

New Member
You may want to REVIEW THIS and also the AN Study Results tab in the calculator spreadsheet and determine if adding loads of P or K is necessary.
I did look at the AN study results in the calculator tab. Perhaps i'm not reading it correctly? but to me it seems like there was a 50% increase in demand of P and 41% increase in demand of K during flowering compared to Veg? I'm not disagreeing with you that increasing P will not increase the amount of budding sites or bud quantity, but i'm thinking it has an effect on the quality of the fruit/flower. More than just that, i just want to play around and see how it goes, learn, adapt.. improve.
I don't plan on running super high PK numbers. Your calculator is tremendous help. I would be lost without it. I'll keep reading more about MegaCrop and NPK in general.
thanks again :)
 
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