Optimising Nuttrient Ratio's for Cannabis Production - A seymore experiment

[Inactive account]

Hello world,

Since watching Nirit Bernstein's video (posted here) and reading the coresponding material, I was quite blown away with their findings! So much so that I need to try this for myself :) The TL;DR version of this video is as follows.

- Ratios matter a lot!
- Stressed, nutrient deficient plants produce plants with the most secondary metabolites.
- Optimal available Nitrogen DOES NOT change throughout the plants lifecycle.
- Potassium requirements DECLINE while in the reproductive stage. (100-175ppm for veg, 100ppm for flower).
- Phosphorous requirements only slightly increase during the reproductive phase and has a wide tollerence band. Also, not a lot required 30ppm is optimal for grow and sufficient for flower! Lower is optimatal for secondary metabolite production.
- Cannabis requires quite a lot of Magnesium (30ppm) throughout. It also has a huge influence on secondary metabolates production if deficient. Also has a wide band of tollerence.
- Cannabis does not like amonial Nitrogen (NO3) at all. This is interesting because most of the "off-the-shelf" fertilisers contain amonial nitrogen and some even use it as a marketing angle.
- Calcium requirements drop off as the plant moves into the reproductive stage.
- Humic acid will reduce concerntrations of secondary metabolites.

Base on the above, I'm going to have to completely rethink the way I feed my plants :) Currently, I use RO water with a small ammount of tap water mixed (~5-10%) to add a little Chlorine as my nutrients don't contain any. Lets start by taking the above and making some notes.

- Optimal N for Grow and flower is 160ppm
- Optimal P for grow is 30ppm and 40-60ppm for flower * 15-90ppm acceptable throughout the lifecycle
- Optimal K for grow is 100-175ppm and 100ppm for flower
- Optimal Mg for grow and flower is >30ppm

OK, so let's create a formula that meets the criteria above! I'm not going to discuss additives here as anything I use is more of a biostimulant rather than salt and won't affect the PPM much. I also use RO water as my base so nothing to adjust for here. If I were using municiple water, I'd grab the guarenteed analysis from the suppliers website and adjust the formula accordingly.

I'm currently using GHE Tri-part and for the most of the grow, I've been following the recommendations from the manufacturer. Seems to work OK, but I do seem to get quite a lot of yellowing mid to late flower. Could never make sense of it... until watching the video above. First, let's start by opening a spreadie (spreadsheet) and input all of the percentages from the guarenteed analysis on the back of each bottle.



Next, we need to calculate PPM for each element based on dilution. If you're interested in how this is calculated, post below and I'll open another thread explaining how to do this for yourself but, the short version is that you need to calculate the elemental value of a few salts, then calculate the v/w% based on the dilution rate of each part to water. We can also calculate the percentage of amonial nitrogen and nitrate nitrogen.



So, let's plug in the ratios supplied from Terra Aquatica. First, let's start with grow. The chart suggests the following measurements;

- 1.8mL/L Grow
- 0.6mL/L Bloow
- 1.2mL/L Micro

Now, let's plug in those numbers and look at the PPM for each element.



Hmm, based on the research, we're not looking in great shape :) We're low on N, P and Mg! Everything else is within range. That being said, I've found my plants to be happy on this ratio for the most part. OK, let's make the required adjustments to optimise based on the research above.



That's a HUGE difference! Now all parameters match the optimal for vegative growth based on the research above.

- 1.6mL/L Grow (11% decrease)
- 1.4mL/L Bloom (133% increase)
- 2.2mL/L Micro (83% increase)

Now let's optimise for flower. First, let's use Terra Aquatica's recommendations and see where we sit.



WTF! No wonder my plants are yellowing off in mid to late flower, I'm N deficient! Everything else is within optimal ranges but N is 35% under optimal. Let's now optimise for cannabis based on the research above



As you can see, the ratio of grow/bloom/micro looks completely different, but the PPM is now optimal across the board :) I've also managed to reduce the level of amonial nitrate within the final mix for some extra gains. All this without the need to add any additional CalMag or PK X/Y! Anyways, I'm now about to run this schedule within a small Aeroponics system I have stashed away and I'll let you know the results. I may tweak the ratio a little to bring Ca down a little within the flowing period.

Thought this might make a fun post and to show how you might optimise your nutrition for hydroponics. I'm sure there's further optimisations that could be made to tweak things further. I'll make up the first resovior today and let you all know what the total EC of the solution turns out to be.

Have fun and happy growing :)

[Inactive account]

Hello once again!

So, I've tweaked the grow ratio again slightly to match the requirements and to adjust for some of the micro nutrients. Here's the final grow formula.



This new formula keeps Ca ~100ppm + a small amount from the 10% tap water and pushes Mg up to 35ppm. So, what are the final EC and PH after dilution?

I did add some "nano" :shrug: silicic acid which increases the EC from 0.0 to 0.1. Other additives are TrickoLogic, some Fish sh1t, some Hesi SuperVit and finally, some CannaZym

After adding everything, here's the final EC and PH

PH: 5.8


EC: 1.8


That's pretty much what I aim for within the growth stages :) Also is about right when you calculate the expected EC from the spreadsheet. Considering we've added some additional things and the calculations are based on elemental values.

Plants are The Bird (left) and Banana Frosting (right) from Sensi Seeds. Just some cheapo plants I don't mind killing if it all goes tits up They are a little stressed as they had to be up-rooted from soil and re-planted in aeroponics. As they were quite well established before rehousing, the roots took a little damage. Seem to be still happy though and plenty of white root shooting from the net pots. It just wrote off some of the lower leaves



Environment isn't that far off perfect. I suppose the humidity could be a smidge higher to match the growth stage.



Smoke me a kipper, I'll be back in a week to show you how they respond.

[Wrh]

This is very interesting I'm looking forward to seeing your results thanks for sharing

[Greenfingers]

Looks the dogs danglies mate

[seymore_budz]

I'm back :) So, I had some teething troubles with this grow and ended up with a touch of root rot on the banana Frosting. TBH, both plants have been a pain in the arse with suspected tmv as I have some weird damage on the leaves. That being said, the bird have been doing great. A little tip burn creeping in, but they're growing vigorous and seem to be loving life apart from the root issues. Nursed back to heath by changing the watering schedule to 15/30mins on/off and lots of enzymes.

[Herbalist]

Interesting stuff man. Will be following along. Good luck.

[seymore_budz]

Just to elaborate on the suspected TMV. Both Banana Frosting plants have been a nightmare from the start. Very finicky plants that don't seem to like anything I do. I also started to notice the damage below right after the initial seedling stage. Both the rust spots and the discolouration.

I know it's not abiotic as the other plants are doing great. TMV tends to slow the plants growth, cause weird issues like make the plants shit the bed at the slightest wobble in environmental conditions. Exactly what I'm seeing :) I've also read that tmv can be transfered from the mother plant and onto the seeds. Sice both are showing signs and are from the same pack, I do wonder if it's something to do with the batch of seeds. We will see I suppose. You can see the bird are double the size of the banana Frosting. That could be genetics, but I doubt it.

[seymore_budz]

Hello guys,

So far, so good! Things are looking good considering they were fighting root rot. I'm about to adjust the fertiliser ratio once again as I'm now going to be hitting flower. First with a pre-flower mix and later with the final ratio.

My preflower ratio looks like below:



I've slightly backed off on the EC as I could see the very beginning of tip burn and some signs of early N toxicity on the Banana frosting. I'm using a lot of additives that make things super available to the plant and I think Ca is a little high. This ration keeps the N in the 160ppm range, but drops the Ca and Fe a little to avoid over fertilisation.

I've also dropped the fish sh1t as it was causing issues with my sprayer heads. Still adding TrickoLogic though. I've also started to add some Bud Factor X. I'm hoping it will help out with secondary metabolite production while I keep N high.

Will update in a few weeks when I move over to flower. Sooner if something goes wrong

Plants are still growing rapidly as they transition from grow into flower.

[seymore_budz]

Hey all,

I've decided to move over to my flowering mix as I think that pre-flower mix was a little too N heavy :) All is good apart from the slight N toxicity. I'll probably tweak the N a little next grow.





You can see they're a little dark with the lights out.

[seymore_budz]

Hello guys,

So.... First sign of a deficiency! And it's a micro deficiency. I thought it may be a little bit of heat burn as I let them grow quite close to the light, but I was wrong. Other incident that happened was I didn't test my PH meter and it had drifted about .4 out so my PH was quite low for at least a week. I've corrected that now and I've upped the micro a little. Hopefully it doesn't progress. Everything is within range except Iron that flagged as high, but I set the threshold quite low at 3ppm.