Blueberries and Battery Acid Adventures

I decided to try and grow container blueberries. I used the pine bark and peat moss mix. Then I did something stupid. I added well rotted composted manure to the mix.

I bought one of those cheap Chinese ph soil probes and was disappointed when it never registered any PH level at all. I figured it was just broken. Weeks go by and the plants keep looking worse and worse.

One day I decided to dip the PH probe into some vinegar and all of a sudden it was no longer broken. (it was never actually broken) I realized that my PH was probably over 7 and the blueberries were probably goners.

If they are going to die anyway I will try a hail Mary. I read about people directly using battery acid to adjust the PH of the soil. I would need so much acid that I would probably fry the roots. I decided to remix the potting soil instead.

I removed the plants then I dumped all of the potting soil into a wheel barrow. I mixed about a cup of battery acid into 5 gallons of water and mixed that into the soil in the wheel barrow. After mixing it for 20 minutes the ph meter reads pH5. I repotted the very sad looking blueberries and will report back if they survive or die in the next month. I wonder if the acid was able to neutralize all of the basic buffer material in that 20-30 minutes or will my ph go back up.

Battery acid seems like a pretty awesome idea for general gardening not just blueberries. I might use a moderate amount in the areas I wish to plant soon to pull my ph down below 7, I can use sulfur to keep the ph below 7.

Has anyone else ever used large amounts of battery acid to prepare soil before planting?

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I use battery acid for irrigating Blueberry plants.I hope your meter is accurate,because a cup per five gallons,seems kind of high to me.
Are those final measurements for the soil or water?

I was measuring the ph5 of the soaking wet soil after 20 minutes. I am almost sure the meter is not very accurate. It is hard to tell 4.7 from 5.2. I read about a bunch of people using it for irrigation but haven’t read about people using a bunch of it to start the soil at the right ph.

I would be careful how much you apply. Maybe get some pH test strips, or a bottle of that green crap. I would add the acid in doses, with a day between. It would suck if you added too much acid. I went through 3 pH probe testers in 2 years, and swore off them.

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You must go through a lot of batteries that way. There is lead in the battery acid that is not good for any of you or me. Try going to the roofing company and ask for a gallon of acid used to prep steel gutters for soldering. That will be clean and lead free.

That is not true, that could cause the battery to explode. He is not using used battery acid, yes that has lead, but fresh acid does not contain any lead at all. Nor any heavy metals which is a great way to make a battery bomb. Acid producing companies would be sued out of business. It is also very bad advice to use certain acids on plants, some will not work long term. others may be toxic to plants.
You can buy battery acid at most auto stores. I used to use it on blueberries, but now only for scarification of Rubus seeds. Sulfur has been working for me. For a quick change I would use sulfuric acid for sure.

I have gathered from the web that using sulfuric acid to acidify irrigation water for blueberries is not uncommon. Here are a few links to presentations / articles that discuss the use of mineral acids such as sulfuric acid in blueberry production. The 2nd link deals with growing blueberries in the high pH soil found in Utah. Toward the bottom, just prior to the discussion of different varieties, it discusses the very small amount of sulfuric acid need to acidify irrigation water and makes the recommendation that one measure the pH of the water with a meter. It also has a nice figure that explains the buffering effect of carbonates and aluminum hydroxides found in soils. As clay contains a lot of aluminum hydroxides one can see why clay soils are difficult to acidify to ~ pH 5.


Yes, it is an excellent method often used in commercial operations. Suggested by many Universities. Never use acid out of a battery of course! Buy fresh product! You can by pure acid from chem companies, but I prefer to work with the 30% solution used for batteries. It is much safer to use.

I understand. I thought some of you had access to exhausted unusable car batteries and were draining the acids out.


Yes, it’s great you brought it up as some might do that! It’s best to be clear. Not many even realize you can buy battery acid. Here in the auto stores it’s not even visible. Behind the counter, you have to ask for it. Also that it is 30% and a touch safer than the 90% sold at chemical supply places. The 90% actually smokes, like in the movies (I’m a lab tech and have used it at work before). Battery acid is weak enough to give you a few seconds before it burns to wash it off. Wear eye protection, be safe! S with a hit happens.


To be clear I would never drain the acid from a battery into my soil. Lead is no joke. I bought the over the counter 30% acid. Before I start using the acid, I dilute the acid even further in a jug of water. I mix 1 part acid into 9 parts water while wearing goggles. I never work with the 30% solution except to dilute it. The 3% acid is less dangerous than many household cleaners.

When I want to use the acid to water plants, I dilute it even further and measure it with my ph probe before using it.

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I remember when bamboo rabbit was using the 90% stuff.He described it being like syrup.

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One of my previous jobs was battery installer for telephone offices. We handled HUGE 500 pound batteries routinely. We were required to keep 50 pounds of baking soda on hand at all times just in case of a spill. The one time I needed it, a battery case ruptured, and 50 pounds was nowhere near enough.

Definitely use goggles when working with battery acid. Have a good water source available to wash it off just in case of a spill. Wear old clothes because battery acid does really bad things to most clothing. Yes, accidents happen. You can still be safe.


I’ve used sulfuric acid drain opener before to acidify blueberries. It’s fairly cost effective. Generally they run 90+% sulfuric acid.

For most of them I think they are just H2SO4 and water. You can find an SDS (or MSDS- for older terminology). The SDS lists all the hazardous ingredients. Most of the acid drain cleaners just list the sulfuric acid on their SDS, so I felt pretty comfortable using it. You can get it at any big box store, or hardware store.

Here is an SDS for one of the acid drain cleaners. It lists the ingredients as just water and sulfuric acid.

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90% is too scary for my blood. One quart of 30% lasts a long time if you take your water down to 5 pH or so, and is low enough that you don’t have to worry too much about adding water to acid & such.

I got it from an auto supply store and it is just water & acid.

I’m trying again this year.

My experience is that regulating ph in containers down to blueberry levels is difficult. In my case I overshot the mark.

The method of having lots of S which the bacteria turns into Sulfuric acid is one way. Then they advise you to use at least a minimal amount of commercial sulfuric acid to control the alkalinity in tap water. I used liquid drain cleaner. Then you have the natural ph of your growing media which can move around in its own. Then there is the acidity that may attend urea-based or ammonium sulfate based ferts.

That’s quite a few moving parts for a container.

This time I’m going to take Harvestman’s approach: Get it around 6.0 or maybe a little less and call it a day.

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Wow. Dropping 50 lbs of baking soda on the equivalent of concentrated acid must have generate a lot of heat!

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This was on a heavy vinyl tile floor. The acid lifted the tile up off of the concrete and started etching away the concrete. We used all the baking soda we had and went to a small local store to buy out all they had which was about another 20 pounds.

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Getting containers to pH 5.5 is not too hard. Unbuffered peat moss will drop to 5.5 when it decomposes. Use bone, cottonseed, and feather meal for nutrients. If you inoculate with fungi & microbes and feed it molasses water, the pH should drop in 3-6 weeks. Bark will also acidify, but not as fast as peat moss.
I learned to add a small amount of dolomite to peat based potting mixes, because the manufacture’s lime buffer always seemed to run out during the 3rd month. The pH drop is more of a crash. It will drop from 6.3 to 5.5 in a couple of days. Once the manufacturer’s lime buffer is consumed/overcome, there is nothing to keep the pH out of freefall. The mild pH buffers tend to have low solubility, and take weeks to leech out.

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I used the liquid drain cleaner.

Taking all precautions, I would mix, as I recall, 15-19 ml sulfuric acid into a half-filled 1.75 liter glass container. Then I would fill the rest up with water.

The end product would be about like pickling vinegar. Strong, but no longer life threatening.

A couple of capfuls would turn my bucket of tap water into acid rain.

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