Phosphorus Use From Flower Initiation Onward

[pjlive]

There's a lot of mixed opinion on whether or not a boost in phosphorus during flower initiation will improve bud volume and densities by harvest. What do you do?

 

[GMT]

As in P alone, or P and K levels? I'm interested, but yet to see any proof of the P alone trend in bottled nutes.

 

[pjlive]

As in P alone, or P and K levels? I'm interested, but yet to see any proof of the P alone trend in bottled nutes.

I'm wondering about people's specific use of P. Potassium levels I always ramp up going into harvest (two weeks or less). I'm definitely a P skeptic myself. But, I'd like to see what other growers have been doing. It would be nice to know for sure if it's a myth or not when used specific to cannabis plants.

Also, I see some of the salt fertilizer manufacturers continuing to market their typical 10-30-20 Bloom packs, but now am seeing more people actually using 05-50-18 for bud set and flower then going down to something like a 7-15-30 to finish.

 

[f-e]

There is an often cited paper, where P level in general agriculture was looked at. Something like 10ppm 20ppm 30ppm where 30ppm was best. The paper doesn't look at 40ppm though.
Most bottles are coming in around 30-50ppm. The 100-100-200 guidance has me head scratching. Forum users have said it's elemental. One AG UNI runs 200-200-200 and have not had their funding pulled yet. I did a low P run, at around 20ppm. I wouldn't repeat it. I think 45ppm is ample though, even for P hungry plants like skunks.

There are two main schools of thought. Many run between 25 and 50ppm, which is probably supported at the lower end by the use of medium that contains P. The other main group aim between 100 and 200. About 25% of commercial growers fall in each.

I did a few runs with about 100ppm in coco, and with my small pots, they just didn't want it. They didn't take half of it. The runoff figures (lab tested) showed this.

I have not done enough testing to write a university paper on this. I believe Early P and Ca starts at the end of veg, about a week/10 days before the 12/12 switch. Both accumulate in the plant at this time. Adding one causes use of the other, so we have to speak about both. P loading at this time seems to carry us through the peak of P use, which is steered towards an earlier date. After which P use is fairly steady. This means we can be quite consistent with the P given. Though some heavy P users won't say no to a bump just before half time. I'm talking big heavy 8 weekers, taking a bump around 25 days. However, that level of tuning really isn't something to do until you know your plants want it, from past grows with them. A level of dialing in that's really not needed to hit the numbers on the seed packet. I myself am very wary of such boosts, as I do a mixed crop that's constantly evolving. Basically.. I'm never that dialed in.

 

[GrowControl]

I choose "I increase my phosphorus levels starting at flower initiation but never overdo it.", simply because that worked me well.

(My P source have some N in it also)

Maybe I'm pushing my ladies too hard, but I've had P deficiency in my previous 3 rounds, but there were always clear signs of whats happening, and after mitigating (giving the correct nutrients), the issue has been resolved.

I think there is no golden schedule, you cant follow 1:1 somebody's feeding and watering schedule, because you dont have the same environment, the same par ratings, humidity, temperature, etc (unless you do, ofc then you can). Right?

 

[f-e]

Yup. No one size fits all.


Last study I saw on K, showed it did nothing. Oddly it did for vegetative type growth, but nothing for flower weight. That was rows at different concentrations, repeated at 5 different locations. I'm happy to about 180ppm, after which it traditionally causes me problems. One study saw a plant go downhill about 180 yet another plant was picking up at 180 and seemed to like perhaps 240ppm. That was just total plant matter at 4 weeks though. The researchers thought that enough?

 

[pjlive]

There is an often cited paper, where P level in general agriculture was looked at. Something like 10ppm 20ppm 30ppm where 30ppm was best. The paper doesn't look at 40ppm though.
Most bottles are coming in around 30-50ppm. The 100-100-200 guidance has me head scratching. Forum users have said it's elemental. One AG UNI runs 200-200-200 and have not had their funding pulled yet. I did a low P run, at around 20ppm. I wouldn't repeat it. I think 45ppm is ample though, even for P hungry plants like skunks.

There are two main schools of thought. Many run between 25 and 50ppm, which is probably supported at the lower end by the use of medium that contains P. The other main group aim between 100 and 200. About 25% of commercial growers fall in each.

I did a few runs with about 100ppm in coco, and with my small pots, they just didn't want it. They didn't take half of it. The runoff figures (lab tested) showed this.

I have not done enough testing to write a university paper on this. I believe Early P and Ca starts at the end of veg, about a week/10 days before the 12/12 switch. Both accumulate in the plant at this time. Adding one causes use of the other, so we have to speak about both. P loading at this time seems to carry us through the peak of P use, which is steered towards an earlier date. After which P use is fairly steady. This means we can be quite consistent with the P given. Though some heavy P users won't say no to a bump just before half time. I'm talking big heavy 8 weekers, taking a bump around 25 days. However, that level of tuning really isn't something to do until you know your plants want it, from past grows with them. A level of dialing in that's really not needed to hit the numbers on the seed packet. I myself am very wary of such boosts, as I do a mixed crop that's constantly evolving. Basically.. I'm never that dialed in.

Wow. Thanks f-e for putting the time in to answer so thoroughly. I do appreciate it! All of your info is really good for me to read.

Personally, I do increase P as soon as veg ends and flower begins. But no where near as much as we're seeing some do in coco and peat mixes since legalization has occurred in different places around the world. When I see 100 ppm I think it's way too much, but to think some growers are going all the way up to 200 ppm seems wasteful and maybe even blind (that they're relying on "Bro" science maybe???). I don't know.

Very helpful. Thanks again!

 

[pjlive]

I choose "I increase my phosphorus levels starting at flower initiation but never overdo it.", simply because that worked me well.

(My P source have some N in it also)

Maybe I'm pushing my ladies too hard, but I've had P deficiency in my previous 3 rounds, but there were always clear signs of whats happening, and after mitigating (giving the correct nutrients), the issue has been resolved.

I think there is no golden schedule, you cant follow 1:1 somebody's feeding and watering schedule, because you dont have the same environment, the same par ratings, humidity, temperature, etc (unless you do, ofc then you can). Right?

Thank you, GrowControl! Very nice of you to chime in with your info. I do appreciate it very much.

Again, what I'm seeing from you is that when it comes to P, you balance your use based on your plants and the environmental conditions they're in at any given time. I'm the exact same way. It seems like common sense!

I'm really now very curious and interested in why such high levels of P are being recommended by some. I'm now leaning towards the fertilizer manufacturers being the real problem here. But, if it is them and they're pushing their new "Cannabis Mixes" for Bloom cycles at crazy high P ppms because people believe a significant ramp-up of P will increase their yields and the overall density and appeal to their plants buds, it seems INSANE. Why would any fertilizer company intentionally present their customers with a product they know will not work out for their plants AND add to hazardous environmental practices?

I'm definitely going to be keeping my P use in balance. Just based off what you and f-e responded with here. Hopefully one or two more growers will chime in too. We'll see.

Thank you again. Very nice of you!

 

[pjlive]

Yup. No one size fits all.


Last study I saw on K, showed it did nothing. Oddly it did for vegetative type growth, but nothing for flower weight. That was rows at different concentrations, repeated at 5 different locations. I'm happy to about 180ppm, after which it traditionally causes me problems. One study saw a plant go downhill about 180 yet another plant was picking up at 180 and seemed to like perhaps 240ppm. That was just total plant matter at 4 weeks though. The researchers thought that enough?

Wow....

 

[xet]

I would choose more Sulfur during flower. A natural Gypsum with Calcium+Sulfur to eliminate the threat of bud rot, increase bud size, and directly increase terpene production.

 

[pjlive]

I would choose more Sulfur during flower. A natural Gypsum with Calcium+Sulfur to eliminate the threat of bud rot, increase bud size, and directly increase terpene production.

Yes. I actually do this myself sometimes. I'm also a big user of silica during both veg and flower cycles in addition to other small boosts. Gypsum, for me, is an essential part of my mix as I use it to counter the pH of the Lime I use in addition to its great nutrient properties.

Thanks for your input!

 

[Popey]

How about this?

https://www.growersunderground.com/PhosphorusMyth.pdf

 

[pjlive]

How about this?

https://www.growersunderground.com/PhosphorusMyth.pdf

Thanks for this analytical report! I have just skimmed it but will review it in detail later today. Just from the skim I can see a moderate bump to P with a somewhat higher bump to K is what things are dialed into. That's the way it's been forever and a day for me, too.

I'm completely at a loss as to why there's this push to flood P into your cannabis plants potential uptake past 50 ppm. 100-200 ppm??? What's going on with this?! I'm currently fluctuating P somewhere between 30-45 ppm depending on the plant at key stages of development.

Something, somewhere, isn't right.

 

[nono_fr]

Hello !

To know what / when to give, I follow this Aptus planning :

I also use silica both veg / flower to have strong structure ! Silica makes strong branches .

 

[pjlive]

Hello !

To know what / when to give, I follow this Aptus planning :
View attachment 18714257
I also use silica both veg / flower to have strong structure ! Silica makes strong branches .

Hello, my brother! Thank you so much for your input here. I very much appreciate it!

Indeed, silica is a wonder elixir for cannabis plants. I'll never be without it now that I've seen what it can do when used in the right amounts. Stopped using vermiculite in favor of a fully soluble additive for a few years now and will never go back.

Your graphic shows a very normal range of P throughout growth with a reasonable tapering off into the finish.

Thanks again, brother. Hang loose and stay happy!

 

[f-e]

View media item 18057926
That's bit hard on the eye. It's last years study of commercial growers, some of which are in fields. They were surveyed to see just how much they were using. A squint at the P table shows 21% of growers went past 200ppm in early bloom. The average figures are also there. P gives weed that samey chemical taste that you smell at the door of most outlets. A taste that is skunky, yet seems to be everywhere.

 

[pjlive]

View media item 18057926
That's bit hard on the eye. It's last years study of commercial growers, some of which are in fields. They were surveyed to see just how much they were using. A squint at the P table shows 21% of growers went past 200ppm in early bloom. The average figures are also there. P gives weed that samey chemical taste that you smell at the door of most outlets. A taste that is skunky, yet seems to be everywhere.

Ah!!! I see.

Thanks once again, f-e, for the excellent info!

 

[xet]

Yes. I actually do this myself sometimes .. Gypsum, for me, is an essential part of my mix

Some years you use Gypsum and some years not and Gypsum is also your essential mix? Gypsum to counteract Lime? I feel I showed up here and got trolled.

 

[pjlive]

Some years you use Gypsum and some years not and Gypsum is also your essential mix? Gypsum to counteract Lime? I feel I showed up here and got trolled.

? I always use gypsum. I don't understand what you mean. I used to use vermiculite up until a few years ago but now I use only soluble silica.

 

[xet]

Gypsum as a soil additive: use it or lose it?

The soil additive gypsum is not well understood and has limited uses in the calcareous-soils of Michigan.

www.canr.msu.edu

"In order to adjust soil pH, liming products must contain carbonate (CO3-) which reacts with hydrogen ions to neutralize soil acidity.

• Gypsum is calcium sulfate (CaSO4). While the calcium will displace hydrogen ions, these ions will remain in solution and will not adjust soil pH."