Lowering ph of soil

Ruzz1974

Well-Known Member
I've done a slurry test of my soil and it is showing 7.35, my plants are showing early signs of deficiency and they are in their 2nd wk of flower, the soil I purchased was advertised as 6-7 ph and I've been feeding the with a pH of 7.3 using bio bizz nutes at their specified ratio, I didn't alter the pH as I believed it wasn't necessary in soil. Question how do I lower my soil pH to sit at around 6.5 so that my plants can take in all the nutes that they require. I have ph down, will this be of any use?
 

Richard Drysift

Well-Known Member
One easy way is to add a bunch of active organic material to your pots. Could be a simple worm casting top dressing but brewing the vermicompost as a tea maybe along with molasses and kelp meal should push ph down slightly for proper absorption. Teas go to work much faster than a solid dressing because brewing tea makes whatever you add soluble. Adding ph +\- will do nothing because it is the mix itself that regulates ph in soil grows. You need microbes actively decomposing organic matter to keep ph in range.
For a ph too low add mineral inputs like D-lime, gypsum, and /or crushed oyster shell as a buffer. This is usually done when there are no plants growing in the soil. After this run put your used soil in a tote bin or something and add mineral inputs, fertilizer, and compost and then let it set for 30 days which normalizes ph. Should be good for another run; the more times you recycle the better your soil will become. The idea is to put everything that is needed for that particular stage of growth before there are plants in it; then you just add water.
 

DoubleAtotheRON

Well-Known Member
An easy way to get back into the 6.8- 6.5 zone is to flush 3 times the amount of a more acidic mix....or pain water. For example.... lets say you want to drop it from 8 to 6.5. Flush with twice the amount of mix minus the number you want to decrease.. flush with 4ph minus 2.5 (2.5ph) plain water at 3 times the amount of the volume of the pot to level at 6.5. Use the opposite to increase. Sounds crazy I know, but It works.
 
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PadawanWarrior

Well-Known Member
I've done a slurry test of my soil and it is showing 7.35, my plants are showing early signs of deficiency and they are in their 2nd wk of flower, the soil I purchased was advertised as 6-7 ph and I've been feeding the with a pH of 7.3 using bio bizz nutes at their specified ratio, I didn't alter the pH as I believed it wasn't necessary in soil. Question how do I lower my soil pH to sit at around 6.5 so that my plants can take in all the nutes that they require. I have ph down, will this be of any use?
How are you testing pH? I mean are you using a meter or drops? I assume you used distilled water for the slurry test.
 

PadawanWarrior

Well-Known Member
An easy way to get back into the 6.8- 6.5 zone is to flush 3 times the amount of a more acidic mix....or pain water. For example.... lets say you want to drop it from 8 to 6.5. Flush with twice the amount of mix minus the number you want to decrease.. flush with 4ph minus 2.5 (2.5ph) plain water at 3 times the amount of the volume of the pot to level at 6.5. Use the opposite to increase. Sounds crazy I know, but It works.
Funny. I was just talking about this earlier today with someone. Should be a sticky, :lol:.
 

DoubleAtotheRON

Well-Known Member
Funny. I was just talking about this earlier today with someone. Should be a sticky, :lol:.
Renfro taught me almost everything I know.... alot was experimentation. But he is a master.
 

DoubleAtotheRON

Well-Known Member
How are you testing pH? I mean are you using a meter or drops? I assume you used distilled water for the slurry test.
Slurry tests are useless. You really need a good Swiss glass tip probe (direct soil probe) to see exactly what is going on in your root zone.. tools aint cheap, but it can save a crop for sure to within a thousandth of a point in a few seconds.
 

Ruzz1974

Well-Known Member
How are you testing pH? I mean are you using a meter or drops? I assume you used distilled water for the slurry test.
I'm using ro water from our home tap and a calibrated pen which has been calibrated in solution, I have both ro and normal in our home. Normal tap water is 230 ppm @ 7.6 ph
 

Ruzz1974

Well-Known Member
So if I'm right then.
6.5 (ideally) - 7.35 (currently) = -0.85
6.5 + - 0.85 = 5.65

So I should be watering with a pH of 5.65 to start with and monitor and if my soil does buffer slightly and ph drifts then I may have to keep on monitoring throughout the grow and adjusting to keep soil at 6.5?
 
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go go kid

Well-Known Member
How to lower pH in soil
In order to correct alkaline soil, you will typically need to introduce a source of acid. You can add compost, manure, or organic soil amendments like alfalfa meal to increase the nitrogen level of the soil which will also gradually decrease the pH.

Organic gardeners commonly use elemental sulfur to decrease the pH level of their soil; however, sulfur requires some time (6 months+) for the soil bacteria to convert it to sulfuric acid.

The speed of the conversion is dependent on the particle size of the sulfur, the temperature and the degree of moisture of the soil, and the amount of bacteria present.

Sulfur will only work during the warmest months of summer when bacterial activity peaks. It can therefore take up to several months for this method to decrease the soil pH value.

Elemental sulfur is the best choice for lowering the pH of very dense soil, such as soils with a heavy clay component. Also by adding organic materials such as manure to heavy clay soils will help it become more workable, and as a bonus the manure will gradually lower the soil ph naturally.


As it takes so long to act, elemental sulfur is best introduced at the end of the last planting season.

How to lower pH in soil fast
What is the fastest way to lower pH in soil? – While there are methods that will make the soil more acidic very quickly, their results may vary, and in some cases, they may over-correct the soil pH and do more harm than good. The following methods will lower the soil pH quicker than elemental sulphur but as they are fast acting, you should add them to the soil in measured doses.

Using Coffee to lower soil pH
While it’s a well-known myth that coffee grounds are a quick fix for lowering soil pH, in fact, most of the organic acids in coffee are water-soluble coffee and flush out into the brew. Used coffee grounds have a pH of around 6.8, which is so close to neutral that they won’t lower pH much; however, they do add a little nitrogen, so they can help reduce pH over time, just like manure or compost.

Coffee grounds are almost neutral pH, the acidity is flushed out with the hot water.
Coffee grounds are almost neutral pH, the acidity is flushed out with the hot water.
Freshly ground or brewed coffee has an average pH of about 4.5, depending on the region in which it was grown. So if you need to drop soil pH more quickly, try watering your plants with leftover (cold) coffee that is diluted 50-50 with water. This method works especially well for smaller volumes of soil such as for houseplants or container vegetables.


How to lower pH in soil with vinegar
Vinegar is a kitchen staple because it has a wide variety of uses; it can be used as a condiment, to add flavor to cooked dishes, and even to clean sinks and counters when the cooking is done. This potent liquid is also useful to gardeners, and it can be used to naturally adjust the pH level of soil without the need for harsh, commercially manufactured products.

Vinegar is a diluted, liquid form of acetic acid, and depending on what the vinegar is made from and how it’s processed, it may also contain other things, like traces of vitamins and minerals. The average pH of commercially manufactured white vinegar, like that sold in supermarkets, is 2.4, making it highly acidic. Organic gardeners can find organically-made vinegar.



Vinegar can be sprayed onto the soil or introduced through an irrigation system. A cup of vinegar mixed with a gallon of water is ideal for plants like azaleas and rhododendrons. Vinegar can be bought in bulk much cheaper than small bottles like this Heinz Multi-Purpose Vinegar (1 Gallon) from Amazon.

Aluminum sulfate to lower soil pH
One of the quicker-acting acidic soil additives is aluminum sulfate; it produces acidity in the soil as soon as it dissolves, which is basically instantly as long as moisture is present. If you need to urgently lower the pH level of your soil, aluminum sulfate is a great choice.

Keep in mind that using too much additive can be harmful for your plants, so it’s best to verify the usage details based on the starting pH of your soil. Aluminum sulfate shouldn’t be used for large applications because it can lead to aluminum accumulation or even aluminum toxicity in the soil.



Mix around 5lbs of aluminum sulphate around the base of the plant you want the soil ph lowered to reduce the pH by around 1 unit. Always check the dosage on your label before application. Have a look at this Aluminium Sulphate from Bonide Products to see if it works for you.

Sulfur-coated urea to lower soil pH
A common ingredient in many slow-release commercial fertilizers, sulfur-coated urea is a fairly quick-acting soil additive. It can lower the pH level of the soil considerably over time, yet will produce some effect within a week or two of being introduced.

If you were already planning to fertilize the soil as well as decrease its pH, simply choose a fertilizer that contains urea; the sulfur-coated urea content does vary from one brand of fertilizer to another, so remember to consult the mixing instructions to determine the proper amount to use.

Iron sulfate to lower soil pH
A good choice for heavily compacted soil with high clay content, iron sulfate, and aluminum sulfate relies on a chemical reaction to create acidity in the planting beds, making it less dependent on temperature conditions than elemental sulfur which relies on a slower biological reaction to begin any changes in soil ph.

Both Iron sulfate and Aluminium sulfate act faster than elemental sulfur and can significantly reduce pH in as little as three or four weeks; therefore, it can be used during the same season you decide to plant acid-loving plants.

It may take more than 10 pounds of iron sulfate per 100 square feet of soil to reduce the pH level by one; if you do need to add more than that, it’s best to split the quantity into two applications that are spaced a month or two apart. This will give the soil enough time to absorb the iron sulfate between applications.

Iron sulfate can leave rusty stains on clothes, so it’s best to wash any clothes that have come into contact with them separately to avoid damaging other items; they can also stain cement surfaces such as patios or sidewalks.

If you have a smaller area of soil you would like to treat, take a look at this 4lb bag of Iron Sulfate from High Yield – It says it treats 1000 square feet which seems a lot for 4lbs – I would still apply one dose at a time and check your levels again afterward.

Summary

In summary, I would say that the most important thing to do first is to measure the soil pH. – I would recommend you buy your own soil pH meter or fill a bag with your soil and take it to your local agricultural shop for soil analysis.

When you get your results back you can begin to amend the pH in whichever way you choose. The coffee and vinegar methods would be ok in small potted areas but not really realistic for large areas.

To lower the pH in larger areas I would use elemental sulfur if I wasn’t in a rush- but usually, you do want the benefit within that growing season. In this case, I would choose Iron Sulphate as my first choice (this will help to reduce aluminum toxicity in the soil) and if I couldn’t get that then my second choice would be Aluminium Sulphate.

If you would like more about soil, its profiles, and horizons, take a look at my article “How Soil is Created” for more info.

Thanks for reading and good luck- Richard.

Further reading:

https://hortnews.extension.iastate.edu/1994/4-6-1994/ph.html

https://www.extension.purdue.edu/extmedia/ho/ho-241-w.pdf
 

Ruzz1974

Well-Known Member
How to lower pH in soil
In order to correct alkaline soil, you will typically need to introduce a source of acid. You can add compost, manure, or organic soil amendments like alfalfa meal to increase the nitrogen level of the soil which will also gradually decrease the pH.

Organic gardeners commonly use elemental sulfur to decrease the pH level of their soil; however, sulfur requires some time (6 months+) for the soil bacteria to convert it to sulfuric acid.

The speed of the conversion is dependent on the particle size of the sulfur, the temperature and the degree of moisture of the soil, and the amount of bacteria present.

Sulfur will only work during the warmest months of summer when bacterial activity peaks. It can therefore take up to several months for this method to decrease the soil pH value.

Elemental sulfur is the best choice for lowering the pH of very dense soil, such as soils with a heavy clay component. Also by adding organic materials such as manure to heavy clay soils will help it become more workable, and as a bonus the manure will gradually lower the soil ph naturally.


As it takes so long to act, elemental sulfur is best introduced at the end of the last planting season.

How to lower pH in soil fast
What is the fastest way to lower pH in soil? – While there are methods that will make the soil more acidic very quickly, their results may vary, and in some cases, they may over-correct the soil pH and do more harm than good. The following methods will lower the soil pH quicker than elemental sulphur but as they are fast acting, you should add them to the soil in measured doses.

Using Coffee to lower soil pH
While it’s a well-known myth that coffee grounds are a quick fix for lowering soil pH, in fact, most of the organic acids in coffee are water-soluble coffee and flush out into the brew. Used coffee grounds have a pH of around 6.8, which is so close to neutral that they won’t lower pH much; however, they do add a little nitrogen, so they can help reduce pH over time, just like manure or compost.

Coffee grounds are almost neutral pH, the acidity is flushed out with the hot water.
Coffee grounds are almost neutral pH, the acidity is flushed out with the hot water.
Freshly ground or brewed coffee has an average pH of about 4.5, depending on the region in which it was grown. So if you need to drop soil pH more quickly, try watering your plants with leftover (cold) coffee that is diluted 50-50 with water. This method works especially well for smaller volumes of soil such as for houseplants or container vegetables.


How to lower pH in soil with vinegar
Vinegar is a kitchen staple because it has a wide variety of uses; it can be used as a condiment, to add flavor to cooked dishes, and even to clean sinks and counters when the cooking is done. This potent liquid is also useful to gardeners, and it can be used to naturally adjust the pH level of soil without the need for harsh, commercially manufactured products.

Vinegar is a diluted, liquid form of acetic acid, and depending on what the vinegar is made from and how it’s processed, it may also contain other things, like traces of vitamins and minerals. The average pH of commercially manufactured white vinegar, like that sold in supermarkets, is 2.4, making it highly acidic. Organic gardeners can find organically-made vinegar.



Vinegar can be sprayed onto the soil or introduced through an irrigation system. A cup of vinegar mixed with a gallon of water is ideal for plants like azaleas and rhododendrons. Vinegar can be bought in bulk much cheaper than small bottles like this Heinz Multi-Purpose Vinegar (1 Gallon) from Amazon.

Aluminum sulfate to lower soil pH
One of the quicker-acting acidic soil additives is aluminum sulfate; it produces acidity in the soil as soon as it dissolves, which is basically instantly as long as moisture is present. If you need to urgently lower the pH level of your soil, aluminum sulfate is a great choice.

Keep in mind that using too much additive can be harmful for your plants, so it’s best to verify the usage details based on the starting pH of your soil. Aluminum sulfate shouldn’t be used for large applications because it can lead to aluminum accumulation or even aluminum toxicity in the soil.



Mix around 5lbs of aluminum sulphate around the base of the plant you want the soil ph lowered to reduce the pH by around 1 unit. Always check the dosage on your label before application. Have a look at this Aluminium Sulphate from Bonide Products to see if it works for you.

Sulfur-coated urea to lower soil pH
A common ingredient in many slow-release commercial fertilizers, sulfur-coated urea is a fairly quick-acting soil additive. It can lower the pH level of the soil considerably over time, yet will produce some effect within a week or two of being introduced.

If you were already planning to fertilize the soil as well as decrease its pH, simply choose a fertilizer that contains urea; the sulfur-coated urea content does vary from one brand of fertilizer to another, so remember to consult the mixing instructions to determine the proper amount to use.

Iron sulfate to lower soil pH
A good choice for heavily compacted soil with high clay content, iron sulfate, and aluminum sulfate relies on a chemical reaction to create acidity in the planting beds, making it less dependent on temperature conditions than elemental sulfur which relies on a slower biological reaction to begin any changes in soil ph.

Both Iron sulfate and Aluminium sulfate act faster than elemental sulfur and can significantly reduce pH in as little as three or four weeks; therefore, it can be used during the same season you decide to plant acid-loving plants.

It may take more than 10 pounds of iron sulfate per 100 square feet of soil to reduce the pH level by one; if you do need to add more than that, it’s best to split the quantity into two applications that are spaced a month or two apart. This will give the soil enough time to absorb the iron sulfate between applications.

Iron sulfate can leave rusty stains on clothes, so it’s best to wash any clothes that have come into contact with them separately to avoid damaging other items; they can also stain cement surfaces such as patios or sidewalks.

If you have a smaller area of soil you would like to treat, take a look at this 4lb bag of Iron Sulfate from High Yield – It says it treats 1000 square feet which seems a lot for 4lbs – I would still apply one dose at a time and check your levels again afterward.

Summary

In summary, I would say that the most important thing to do first is to measure the soil pH. – I would recommend you buy your own soil pH meter or fill a bag with your soil and take it to your local agricultural shop for soil analysis.

When you get your results back you can begin to amend the pH in whichever way you choose. The coffee and vinegar methods would be ok in small potted areas but not really realistic for large areas.

To lower the pH in larger areas I would use elemental sulfur if I wasn’t in a rush- but usually, you do want the benefit within that growing season. In this case, I would choose Iron Sulphate as my first choice (this will help to reduce aluminum toxicity in the soil) and if I couldn’t get that then my second choice would be Aluminium Sulphate.

If you would like more about soil, its profiles, and horizons, take a look at my article “How Soil is Created” for more info.

Thanks for reading and good luck- Richard.

Further reading:

https://hortnews.extension.iastate.edu/1994/4-6-1994/ph.html

https://www.extension.purdue.edu/extmedia/ho/ho-241-w.pdf
Thank you, great read
 
I've done a slurry test of my soil and it is showing 7.35, my plants are showing early signs of deficiency and they are in their 2nd wk of flower, the soil I purchased was advertised as 6-7 ph and I've been feeding the with a pH of 7.3 using bio bizz nutes at their specified ratio, I didn't alter the pH as I believed it wasn't necessary in soil. Question how do I lower my soil pH to sit at around 6.5 so that my plants can take in all the nutes that they require. I have ph down, will this be of any use?
Slurry test is useless especially in soilless culture. If you have peat based potting mix, you really do not want to lower your pH. Peat itself is acidic, lime is used as pH adjuster. Lime can break down after couple of years and could be partialy leached out of medium by every watering. It means the medium´s pH drops. Its actually almost impossible to rise pH of peat by water alone whatever high the pH of the water is. It just drops back down in minutes. Runoffs ph also tells nothing about mediums ph. So its kinda like slurry test, useless. Post pics of the plants and tell more about your routine and setup. Maybe your issue is not pH related as been already said and for measurment of mediums ph you need proper tools, but thats been already said also.
 

DoubleAtotheRON

Well-Known Member
To the OP... you're going to have 3 different readings on ph. What you're feeding in, what it's at in the root zone, and what it's reading with run off. They're all going to be different. You need to know the root zone PH before you start adjusting things. BUT!.. if you're getting 8 from run off, then you are probably higher in the root zone as it tends to get "diluted" during a feeding.
 

Serpentz

Well-Known Member
I had this problem and the way I was able to fix it fast was by adding a soil acidifier like they use to grow blueberries. I mixed a little of this stuff on the top of the soil...I think it was about 2 tablespoons and after about a week the plant sprang back to life. For me, this was the quickest and easiest way to fix my high ph which was 7.8. The plant was a scrawny nutrient deficient starved thing. It finished nice. Anyone who says you don't need to adjust that high pH don't know what the f*ck they are talking about. Try this and see if it don't help the quickest and easiest way.
 

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Ruzz1974

Well-Known Member
OK update, plants are looking 100% better today, after people advice on whether it may be another underlying issue it got me thinking "when did they start to look deficient and a little droopy" around a week ago, a week after they started flowering, I dropped my temps down to just over 74 from 80 and dropped humidity to 43.
I believe my vpd has been too high the last week and a half and the plant has been over transpiring, when I measured the leaf temps yesterday they we're exactly the same as my ambiant temp, I've now upped my rh to 53 with 74 degrees and today the Plants looks healthier in itself, leaves are all lifted up like it's come out to play. Pics attached to show pics today and of one two days before. P. S
I took a pH reading near the root zone with a neighbours probe which reads 6.87.
 

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