How to bring the pH down?

Phytoplankton

Well-Known Member
Lots of products to bring down ph. I use phosphoric acid, you don’t need much in 5 gallons (my tap water is about 7.5). Though if your growing in bag soil you probably don’t need to mess with ph.
 

bluter

Grow Journal of the Month: July 2020
I'm growing directly in the ground. I'll try to look for some products to bring down the pH. Thanks


shouldn't have to worry about ph if you are direct in to the ground. none of the other garden plants do. you can ph your water if you like, but you're not doing much as far as the plant is concerned.
 

Emilya

Member of the Month: Mar 2019, June 2022 - Grow Journal of the Month: Jan 2020, Aug 2021, June 2022
I'm growing outdoors in the ground and the pH is a little high (6.8) so my question is how do I bring it down into the 6.0 - 6.5 range please?
6.8 is perfect... lowering it will ruin this soil. You are not trying to grow an acidic loving plant like an orchid, you are trying to grow pot. Most people add lime to "sweeten" the soil outside, raising the pH up to where you have it now. If you truly want to acidify your patch, try adding sphagnum peat to your soil and let it cook in a bit. You can also add gypsum before you add plants... but again, this is to make the soil compatable with gardenias, orchids, and citrus trees.... but not pot.
 

SmokingWings

Well-Known Member
I'm growing outdoors in the ground and the pH is a little high (6.8) so my question is how do I bring it down into the 6.0 - 6.5 range please?
As @bluter brings up, if you are growing directly in the ground it is not that big of a deal if the pH is in the range you mention having. In the US each and every county should have a Co-operative Extension Service office which helps area farmers, gardeners, etc. Contact them to get info on their records for the soil in the area. Plus they will help with getting a test done by a laboratory that specializes in soil testing. Outside the US there probably are similar.

Just about anything you add to the soil will take 2 or more years to show the true change. A lot of gardeners try to change the pH of their garden plot and then when the test the next year shows little change they add more of whatever and keep doing it until the pH is way the wrong way.

One of the best ways to get a better crop is to go with the basic organic gardening methods, especially adding compost and mulching with natural/organic materials, and let nature take the worry about pH out of the picture.
 

Phillybonker

Well-Known Member
6.8 is perfect... lowering it will ruin this soil. You are not trying to grow an acidic loving plant like an orchid, you are trying to grow pot. Most people add lime to "sweeten" the soil outside, raising the pH up to where you have it now. If you truly want to acidify your patch, try adding sphagnum peat to your soil and let it cook in a bit. You can also add gypsum before you add plants... but again, this is to make the soil compatable with gardenias, orchids, and citrus trees.... but not pot.
I know 6.8 is perfect.....for most plants. But cannabis plants like the soil a bit more acidic. I read that 6.0 - 6.5 is perfect for cannabis plants, right?, or not really?
 

Emilya

Member of the Month: Mar 2019, June 2022 - Grow Journal of the Month: Jan 2020, Aug 2021, June 2022
I know 6.8 is perfect.....for most plants. But cannabis plants like the soil a bit more acidic. I read that 6.0 - 6.5 is perfect for cannabis plants, right?, or not really?
I have never read that, and if I did I would suspect the knowledge level of the writer who could publicly proclaim such a thing. Soil in closed containers is best used as the very specialized tool it was designed to be, so that instead of any single number, we could use the soil's built in properties to drift us through the entire usable pH range, making absolutely certain that we didn't skip any nutrient because of pH. Setting the soil's base pH to the high end allows this to happen when we come in at the low end with our fluids.

Some people these days believe that we don't need to provide drift for our nutrients and that we should modify our soil so that it doesn't happen. What you are reading is from those neo-bros who have decided to use soil that has been modified to hold the pH in a very narrow range by disabling drift, as you said, between the 6.0-6.5 range. We just have to lump this in with all the thousands of ways to skin a cat and realize that there are many ways to grow this weed. That way will work, if done correctly, but in my humble opinion, the old tried and true methods still remain superior.

Apparently the thing these days is to disable soil's natural ability to provide upward drift by forcing the soil to remain at a set pH, making it harder to maintain and prep to get ready for this method, since some of the buffers need to be neutralized in order to use soil in this way. Using the soil the traditional way there is no need to ever do a slurry test to determine the pH of the soil, no need to run special nutrients that can lower the soil pH, no need to disable the buffers put in there to cause upward drift, no need to do runoff tests... you just simply adjust your fluids to the lower end of the scale and let them drift through the entire range naturally.
 

Phillybonker

Well-Known Member
I have never read that, and if I did I would suspect the knowledge level of the writer who could publicly proclaim such a thing. Soil in closed containers is best used as the very specialized tool it was designed to be, so that instead of any single number, we could use the soil's built in properties to drift us through the entire usable pH range, making absolutely certain that we didn't skip any nutrient because of pH. Setting the soil's base pH to the high end allows this to happen when we come in at the low end with our fluids.

Some people these days believe that we don't need to provide drift for our nutrients and that we should modify our soil so that it doesn't happen. What you are reading is from those neo-bros who have decided to use soil that has been modified to hold the pH in a very narrow range by disabling drift, as you said, between the 6.0-6.5 range. We just have to lump this in with all the thousands of ways to skin a cat and realize that there are many ways to grow this weed. That way will work, if done correctly, but in my humble opinion, the old tried and true methods still remain superior.

Apparently the thing these days is to disable soil's natural ability to provide upward drift by forcing the soil to remain at a set pH, making it harder to maintain and prep to get ready for this method, since some of the buffers need to be neutralized in order to use soil in this way. Using the soil the traditional way there is no need to ever do a slurry test to determine the pH of the soil, no need to run special nutrients that can lower the soil pH, no need to disable the buffers put in there to cause upward drift, no need to do runoff tests... you just simply adjust your fluids to the lower end of the scale and let them drift through the entire range naturally.
Thanks, I was really worrying about the pH being too high. I added Dolomite Lime to some spots before testing the pH which turned out to be 6.8 so hopefully that doesn't raise the pH above 7.

May I ask what do you mean by: "adjust your fluids to the lower end of the scale and let them drift through the entire range naturally"?
 

Emilya

Member of the Month: Mar 2019, June 2022 - Grow Journal of the Month: Jan 2020, Aug 2021, June 2022
Thanks, I was really worrying about the pH being too high. I added Dolomite Lime to some spots before testing the pH which turned out to be 6.8 so hopefully that doesn't raise the pH above 7.

May I ask what do you mean by: "adjust your fluids to the lower end of the scale and let them drift through the entire range naturally"?
Dolomite is exactly what you want to use, because of its ability to set the base pH to very near 6.8 pH. This of course should be done before the grow... trying to adjust soil pH with a plant growing in it is most likely going to cause harm to the plant.

For years the advice has been to set the pH of your nutes or the plain water given between, to 6.3 pH. We know that this is the pH where the most nutes are the most mobile and available to the plant.

At the moment you water with this 6.3 fluid, the entire container's pH becomes 6.3 pH... it has no choice. The water vastly outweighs the soil and its pH becomes that of the container of saturated soil, at any point you could measure.

As the plant begins to use the water, the water table begins to fall, and the top of the container begins to dry out. This dry line is where the magic happens, because as the water table continues to fall, the soil above loses the pH influence of the water and the water goes away, and this allows that area, of now partially wet soil, to start to drift upwards in pH due to the base pH of the soil. The dryer it gets, the closer it gets to 6.8 pH in that region. From the perspective of any nutes and roots in that region, the pH has drifted upwards through the entire range while it dried out.

The dolomite in the soil also has another effect as does the effect of the acidic nutes being used up by the plant. All of these things combined are actually causing the pH of the water to drift upwards slowly too, adding to the effect of the soil reverting back to its base pH.
 

Phillybonker

Well-Known Member
Dolomite is exactly what you want to use, because of its ability to set the base pH to very near 6.8 pH. This of course should be done before the grow... trying to adjust soil pH with a plant growing in it is most likely going to cause harm to the plant.

For years the advice has been to set the pH of your nutes or the plain water given between, to 6.3 pH. We know that this is the pH where the most nutes are the most mobile and available to the plant.

At the moment you water with this 6.3 fluid, the entire container's pH becomes 6.3 pH... it has no choice. The water vastly outweighs the soil and its pH becomes that of the container of saturated soil, at any point you could measure.

As the plant begins to use the water, the water table begins to fall, and the top of the container begins to dry out. This dry line is where the magic happens, because as the water table continues to fall, the soil above loses the pH influence of the water and the water goes away, and this allows that area, of now partially wet soil, to start to drift upwards in pH due to the base pH of the soil. The dryer it gets, the closer it gets to 6.8 pH in that region. From the perspective of any nutes and roots in that region, the pH has drifted upwards through the entire range while it dried out.

The dolomite in the soil also has another effect as does the effect of the acidic nutes being used up by the plant. All of these things combined are actually causing the pH of the water to drift upwards slowly too, adding to the effect of the soil reverting back to its base pH.
Well that's a very detailed answer. I really have a lot of learning to do. It's too late to put down any Dolomite on my other spots as it's getting too close to putting the plants in the ground but I'll monitor the pH.

It should be interesting because with some spots having Dolomite and other spots not it will give me an idea whether Dolomite is even needed at all..
 

bluter

Grow Journal of the Month: July 2020
Yeah but cannabis plants like the soil a little more acidic than most plants.

it's just a bit hard to ph a planet.


It should be interesting because with some spots having Dolomite and other spots not it will give me an idea whether Dolomite is even needed at all..


stick with that thought process. you have the right idea.
 

bobrown14

Grow Journal of the Month: Dec 2017 - Photo of the Month: May 2020
I'm growing outdoors in the ground and the pH is a little high (6.8) so my question is how do I bring it down into the 6.0 - 6.5 range please?
In soil you dont need to do anything. IF your plants are already planted you cant change the soil pH.

To lower the soil pH you can add elemental sulfur but thats only temporary and you cannot add anything to alter pH while a plant is growing in the soil.

Plants have the ability to alter the pH in the rhizosphere (root zone) with root exudate and so do the microbes working symbiotically with the plants roots. That's the natural process and how plants communicate with microbes so the microbes deliver the nutrieints the plant needs at any given time. Its all about the pH at the rhizosphere and that is controlled by the plants root exudate.

If you try and alter soil pH you're going to mess the natural balance up. 6.8pH soil is not a problem. Don't worry about it.


Edit: Do not lime your soil with plants growing in it.

Adding lime will raise the pH - only temporary tho. If you want to lime soil with a pH of 6.8pH its going to RAISE the soil pH temporarily say a few months. Rain water is acidic and why I mentioned to not worry about soil pH if your growing in the ground.

How are we testing your soil pH?
 
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