Correct pH - which is it?

[Logos]

First off, I am new to growing, so I have much to learn. One thing of critical importance I have thus far learned is the importance of correct pH in my soil-less grow. I know that when there is a plant problem to check the pH first. This is all well and good, but only if you know what the proper pH should be. My confusion lies in that some people on this forum state that the proper pH is 6.5, and it is at this level of acidity that most nutrient absorption occurs. Others are emphatic that the best pH level is 5.8. That’s a big difference. Also, how low can pH go before nut-lockout occurs? I would really like to settle this pH issue in my mind once and for all, and perhaps others would as well.

Many thanks to all who respond.

Logos.

 

[Guest]

First off, I am new to growing, so I have much to learn. One thing of critical importance I have thus far learned is the importance of correct pH in my soil-less grow. I know that when there is a plant problem to check the pH first. This is all well and good, but only if you know what the proper pH should be. My confusion lies in that some people on this forum state that the proper pH is 6.5, and it is at this level of acidity that most nutrient absorption occurs. Others are emphatic that the best pH level is 5.8. That’s a big difference. Also, how low can pH go before nut-lockout occurs? I would really like to settle this pH issue in my mind once and for all, and perhaps others would as well.

Many thanks to all who respond.

Logos.

thats because no one ever specifies hydro or soil, that is how you got 6.5 and 5.8....

6.5=soil (usually 6.2-7.0 is fine, 6.3-6.7 ideal)

Hydro= 5.8 (or at least lower... I don't do hydro but I'm pretty sure its around 5.8)

If you soil, just keep it in the mid-six range and you'll be fine.

 

[sproutco]

correct pH in my soil-less grow.

5.6-6.2

 

[Guest]

What exactly is your medium?I shy away from telling anyone to let their ph drop below 6 unless they are growing in water.

 

[hoyt]

heres a nice chart i found, hope it helps!

 

[Guest]

According to that chart in soil grows phosphorous cal. and mag. are locked out below 6.5,thats very interesting.

 

[meduser180056]

I've seen that chart before. It conflicts with this other one I've seen. Pain in the ass.

 

[Guest]

I dont think they are in conflict so much as they are a little different....

The color chart shows the element and the ph range they are most efficient....

The farther out of that range the less efficient or available they are....

The second chart reflects a more true availability over the whole range of ph values....


So phosphorous cal. and mag. are not locked out below 6.5 simply they fall below maximum availability...

 

[Logos]

Charts

Charts

First of all, let me thank you all for your responses. I appreciate seeing these 2 charts, and think that you, Budleydoright, may be right in your assessment of them. However, the color chart specifically says it is for marijuana and so wonder if marijuana is to be considered "special case" as opposed to generalization, which the second chart depicts. Also, I would like to know the source of the first chart, the marijuana-specific chart. The chart is according to who?

Anyway, many thanks to you all.

Logos.

 

[Guest]

I dont see the charts the way you do....

Both are standard nutrient availability charts...


one simply has an overlay of what the author believes is the ideal ph range for cannabis...

 

[inflorescence]

These charts also assume the ratios are perfect. If the ratios are off then at a given pH the element may be available pH wise but may be locked out due to antagonism, etc.

It's way more complex then these simple charts show.

All the variables are inter-dependent. Temp can affect availability, ratios can affect availabilty, pH can affect availabilty, even light plays a role. And ALL these variables interact in sometimes non-linear ways.

 

[Guest]

I dont think thats the case at all...

It simply shows where each element is most available....

 

[inflorescence]

For example, if the pH is 7.0 and you dump 50 pounds of pure Ca onto your soil (and it doesn't change the pH) the K will not be available to the plant, irregardless of the fact that the 7.0 pH may be ideal for the K to be available.

 

[Guest]

Its not an example of what you said....


Which was the charts assume the ratios are perfect...

IMO it makes no such assumption....

again simply it says what ph the element is most availble at....


You are talking about something thats way beyond the scope of the charts....

 

[inflorescence]

I'm just saying I get the feeling that a lot of people like Logos think all they have to do is hit a certain pH and it will take care of their deficiencies/toxicities, etc and it's just not that simple.

 

[Guest]

I'm in soil, but use hydro nutes sometimes. I still set my ph to 5.5-5.8. No problems. PBP Soil formula takes water at 7 down to 5.7. Everytime. So I figure I'm pretty close, with a well balanced organic / soilless medium anyway. Then I come across a book "Advanced Home Gardening" with a chart like the one above - it says that NPK and most micros are most available at 5.5 - 6.0 in soil. It goes on to say that the soil should runoff at about 6 and that an upswing from the water to the soil helps the plant use the most nutes.

But shit - I'm not sproutco.

 

[Logos]

I'm just saying I get the feeling that a lot of people like Logos think all they have to do is hit a certain pH and it will take care of their deficiencies/toxicities, etc and it's just not that simple.

Perhaps I am naive, but yes, if one's NPK ratio is right and the PPM is right, then I do think that it is that simple. Certainly, proper pH alone will not correct deficiences and toxicities, and I never said it would. From the answers, it appears that there is no consensus.

Thanks again.

Logos.

 

[inflorescence]

Perhaps I am naive, but yes, if one's NPK ratio is right and the PPM is right, then I do think that it is that simple.

And that's why you'll never move to the next level.
Drop your ego and realize it's just about impossible to know every little thing about plants, how they function and their interaction with the world around them.

If you think a chart can sum up the actions of a living breathing organism in a simple graph then you'll never have the curiosity to wonder what is wrong with your plants when the graph stops working.

For example,

Do you even see the word pH mentioned anywhere on this chart?

But hey, I guess your ratios are perfect ALL the time.

 

[Logos]

Perhaps I am naive, but yes, if one's NPK ratio is right and the PPM is right, then I do think that it is that simple. Certainly, proper pH alone will not correct deficiences and toxicities, and I never said it would. From the answers, it appears that there is no consensus.

Inflorescence, we are on the same page, just saying the same thing differently. Certainly there are various factors influencing the health of a plant, and if we can keep those factors within a proper range, then the plant presumably will be healthy. Your chart depicts what to expect when a factor is outside of what is acceptable to the plant. I acknowledge this, and always have. I hope you can see that I have no disagreement with you and appreciate your helpful input.

Again, many thanks.

Logos.

 

[the cult]

your doing soilless arent you?

anyway, for soil:

i grew with PH as low as 5.2, also kept some at 6.2, result was similar, a good amount of bud from both types. few would tell you 5.2 works, and i think it may be too close to poisonous (getting below 5.2) for anyone not being really careful, but it does work - i couldnt spot any defs throughout entire grow!!

so i say anywhere between 5.2 - 6.2 to my knowledge, although some still recommend more alkaline than 6.2. i prefer stressing you keep a steady ph instead, you dont want fluctuations.
canna recommends 5.2-6.2 for their soil nutes by the way.

best,
the cult