He discussed that thoroughly in the previous comment-
It seemed to me that at early flowering was what was found as the largest need for N Too much in early or late flower was not desirable and ‘too much’ varies.
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In the mature stage (Stage 3), the plant is big enough and has a large enough fruit load that the maximum nutrient concentration can be applied. N is increased to promote plant growth and development, Ca is increased largely to prevent blossom end rot and K increased to promote fruit sugar loading and general fruit quality.
In their formulas they continue to increase N through harvest.
I think the reasons for increasing or at least maintaining N is the same for both cannabis and tomatoes. You will get bigger yields using N into late flower.
But yield isn’t the only consideration for cannabis. Cannabinoid concentration plays a factor as well. If you use low N in late flower, it seems you can get higher concentration of cannabinoids, probably because there is less plant matter grown (and only slightly less total cannabinoids).
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Let me know when you figure out the perfect NH4 to NO3 ratio to achieve optimal rhizosphere pH lol! Oh, by the way, Merry Christmas.
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Same to you! I’m working on a conversion to use coco. Once I’m back to growing, I think I’ll experiment by monitoring runoff pH through my grows and try adjusting NH4 up or down.
I’m not certain if this is the best way, but if I can keep the runoff in a narrow range to the input, I’d think it should be balanced well.
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Thank you. This past run my runoff pH was ideal until I started trying to boost Ca levels with the Ca EDTA. There was a certain point where I dropped Ca nitrate to low and the EDTA just sent everything out of wack. The Ca acetate also made run off pH rise.
A friend on another forum says he runs around 135 ppm of N from veg to about week 8 of flower. He gets 125 ppm of N from Ca nitrate, and another 10 ppm of N from MAP. He says with this balance of NH4 to NO3, he achieves perfect pH. He drops N to a total of 110 ppm around week 9 depending on strain, and still gets a nice fade with that much N in his mix. Can’t say how they smoke or, taste though with that much N but, increasing the other anions would force the plant to absorb less N in general anyway correct?
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Something like this? That’s for 10 gallons. You get about 8.8ppm NH4 from the calcium nitrate already, and I added 10ppm NH4 from the MAP. This would be about a 6.25:1 ratio. Seems like a lot of P to get from MAP though. Usually I see most P coming from MKP a lot more, because the K budget is usually quite high.
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Yes. Very similar. He does mix upwards of 10 gallons each time. I asked him for his exact recipe so, I’ll see if he lets me have it to get the exact amounts he is using. Is it a bad thing to get that much P from the MAP? I have it on hand, but rarely use it. I figured maybe add a little less MKP and, a little more SOP to hit K numbers.
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You can always balance it out with SOP, but that adds a lot of S. The only issue is that it causes a high EC and changes anion ratios. So in his anions, I imagine he has a high sulfate ratio compared to nitrate. Either that or he’s using MKP to get most K and running a high phosphate ratio? I swear nutrients are like playing whack-a-mole sometimes. 
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For most plants’ root systems, when absorbing nitrogen, there is a clear preference for Ammonium as opposed to Nitrate. But by contrast, the plant’s ability to self-ferment the area of the root zone is so efficient that a plant growing in a solution containing Ammonium as an exclusive source of nitrogen will reduce the solution’s pH down to less than 3.5, and inflict on itself irreversible damage.
For example, growing tomatoes in a solution whose sole source of nitrogen is Ammonium Nitrate, notwithstanding the equal ratio of Ammonium and Nitrate particles in the solution, for every ion of Nitrate the plant will absorb 4 Ammonium ions. The implication of this process where a plant grows in soilless growing medium with limited root volume and receives primarily Ammonium nutrition, is that there is a great chance the root zone will be acid (Graph 1).
To add complexity… it seems that everything comes into play… temperature, fertilization rate, etc. Because the NH4 absorption rate is so much higher than N, it dumps the pH quickly and then there is a slow rise from the nitrate absorption.
I’ll have to think about this. It seems that if your fertigation rate is high (>1/day) then you may need to be careful about the NH4, because it may never reach the depletion needed to cause the pH to rebound. If you are constantly flushing it out and replenishing it, then it seems like you should use low amounts so you don’t cause toxicity.
I think I have seen this in autofeeds too. I have grown in coco with ~6 feeds/day and when I used masterblend (which has higher NH4), my plants didn’t appreciate it.
Perhaps it is better to use low/zero NH4, and use a lower pH feed to let it rise in the medium, rather than try to fight it with NH4, which is possibly one cause of N problems in late flower with higher feed rates.
Edit: Secondly, since coco really likes to bind cations, there may also be a chance that NH4 accumulates slightly in the media. And that could compound the problem even further.
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Ooo do me next I’ve been having great results with 6mL/gal Dyna-Gro “Grow” 7-9-5 with 1g of Potassium nitrate per gallon.
What does that work out to in ppm? I have tried to use hydrobuddy but I cannot figure it out. I suck at this sort of thing.
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I have so many questions… like where does your Ca/Mg come from? Seems ok if you have Ca/Mg from another source that doesn’t add more N.
Edit: fixed N in the formula
Edit2:
- Supplies a high nitrate to ammoniacal nitrogen ratio to promote shorter internodal spacing resulting in stronger stems.
WUT? comes out to like 2.5:1, which is not a high ratio at all.
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Many thanks for the calculations…
my water is ULTRA hard. 350+ ppm out of the tap. I’m assuming almost all of it Ca with some Mg with a little extra iron and silica.
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Wow, yea that’s some super hard water lol. Mine is like 50ppm, so I’m on the opposite end. I don’t have any experience with using water that hard.
Curious – you use coco right? What is your runoff pH usually? and how often do you feed?
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It does require some workaround. Hard to add nitrate N without adding Calcium, most off the shelf complete fertilizers include enough Ca and Mg or close to it for soft water, but half the country has hard water.
I’m in mostly perlite, runoff is same as input generally. With this much alkalinity, pH does not swing easily. I generally feed once per day.
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DynaGro’s lineup has always confused me. Have you ever noticed that “Bonsai Pro” appears to be the exact same thing as grow?
Also, their orchid formula is almost the same with a little less phosphorous and a little more potassium. Likely that’s a sign that they used more DKP (K2HPO4) and less MKP (KH2PO4) – which would probably make the formula more alkaline? But I always though orchids preferred more acidic conditions.
I’ve always wanted to see an analysis of their fertilizers. I find them a little suspect.
Edit: Nevermind – thanks state of Oregon!
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Quite a bit of their lineup doesn’t make sense…for example why is MagPro recommended when their Bloom already has a fuckton of P…they are also all quite light on K hence why the extra K from Potassium nitrate…and like you were saying the ammoniacal/nitrate ratio is off.
In theory, none of these SHOULD work but they do.
I hardly even use the Bloom anymore (just at last third of flower), or any of their additives but the Grow and Fol-Pro are great products. They also have the lowest Ca and Mg of any one part nutrient which is a big reason why I started using them.
And yeah, there is almost no difference in Orchid vs Grow, but growers of certain crops like the name of the plant to be on it haha. Even if Product X was better for tomatoes, if it says “tomato food” the average consumer gardener is going to buy that for their tomatoes every time when they’re at the hardware store.
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Yea that’s probably the reason. Relabel the same thing 3-4 times and tap into new markets. I wouldn’t blame them for doing it, it’s just funny. Seems like you could use the orchid pro if you wanted to use less N overall. I doubt having slightly lower P will make a difference. But on the other hand, I’d bet that you would have to use more pH down.
I recall you’re using sulfuric as a pH down product. Their formulas appear to be low sulfur, so that is probably a good choice. They quote 0.05% S, but it’s not regulated, so I wouldn’t be surprised if it was actually much higher.
The high P and low S in their formulas means they’re using a lot of phosphates – almost certainly a lot of MAP, because of their high NH4, and also magnesium phosphate to supplant epsom.
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@vernal I couldn’t get the numbers to work out from their label. I suspect they’re mostly using magnesium nitrate instead of magnesium sulfate, which they don’t disclose.
But here’s a ripoff formula (including your 1g potassium nitrate), since you can’t get ammonium nitrate anyway:
Zn/Cu is low for high P formulas though, which I think is the main issue with using plant prod micros for this.
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Excellent analysis man thanks.
I’m just using Phosphoric acid now as pH down, I use less than a mL/5 gallons for “Grow” formula and none with “Bloom” as the water is hard enough that it balances perfectly after mixing. That’s nice at least. Silica will fall out of solution after mixing anyway and I suspect my water has plenty to begin with.
Where does the extra N in “Foliage Pro” come from if not from Calnit?
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Likely they just reduced MAP and used more ammonium nitrate instead.
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