Anyone know what sulfur is used in Espoma Soil Acidifier Fertilizer?

I already have ammonium sulfate which is great for quick acidification but I think that because its so water soluble it probably doesn’t last very long in terms or reducing acidity.

I like Espoma Soil Acidifier Fertilizer which claims to slowly acidify soil but I when I look at the granules it looks (and smells :yum:) like its composed of 80% Milorganite type fertilizer and 20% sulphur granules.

Their fact sheet (pdf) states:

Sulfur (S)…30%
18% … Free Sulfur
12% … Combined Sulfur
Derived from: Elemental Sulfur and Gypsum

How can replicate this?

Shout out to @Richard who seems to be particularly technically capable

Try prilled sulfur.

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Sulfur is slow acting but be careful not to add too much. It takes about 6 months to work, so don’t keep adding more! In a container situation it is easy to kill plants with sulfur.

I like this product for ease of use.


i use the same pellets, cheaper in 50lb bags and spreads well using a broadcast spreader. stuff i use is 90% elemental with a binder i think.

@Richard @Drew51 @TheDerek

Based on the MSU guidelines I found it seems you should only apply 0.15 oz/sqft at a time for established plants. Importantly they say you should not apply during fall / winter as elemental sulfur needs soil temps above 55°F to work.

Unfortunately, it looks like it takes 0.06 - 0.29 oz/sqft to lower pH by just 0.5 depending on soil type. My plan currently is to do an every 2-3 month application during spring and summer until I get to 5.5 and then switch to an every 3-4 month application.


Methods of purification and prilling vary across manufacturers and labels. For correct dosages, follow the label on the container you purchase.

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I’m not sure what you are growing but I myself found it easier to build a 1 foot high raised beds, filled with pete moss, and pine bark fines, both have a pH of 5.0. So you have 1 foot of acidic soil. I mounded the raised beds too to account for settling, and it’s all organic material that will decompose with time. This has worked very well for me. trying to keep the soil pH low over time is tough. I gave up with in ground attempts. Like trying to maintain a fresh water spot in the middle of the ocean.

True, and it also needs 6 months to a year for the bacteria to metabolize the sulfur to sulfuric acid. My experience is pH starts to lower in about a month, and pH continues to drop for the rest of the season. How far depends on amount used. I find it too difficult to manage myself. It’s easier just having acidic soil in the first place, ie raised beds.
I still use a little on my old raised beds as the hydrogen seems to vary more the older the bed gets. I believe the composting process as the organic material becomes old raises the pH, at least that’s my theory as to why the pH started going up in the older beds.


what do you add to this mix for a fertilizer? or is the organic material in there enough alone? I’m doing cranberries , this spring, in raised beds this way. was going to add worm castings for some fertilizer and help with water retention. then 4in of wood chip mulch on top…

Well the sulfur is just for the soil. The espoma soil acidifier is not really a fertilizer. I myself just use sulfur on the need to acidify soil, and I suggest not to use this product it’s no better than sulfur and costs a lot more. I would use Holly-Tone for an organic it feeds the cranberries or blueberries and also has some sulfur in it too.

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i meant to the peat and bark fines. shouldn’t need sulfur with that mix. i make a super soil as a amendment to my beds from a cannabis growing recipe called sub cools super soil. once cured for a few months in a barrel, it only takes a little of it mixed in the beds to add fertility. its so hot., you can’t plant anything directly into it. if i don’t have any made i add worm castings and compost. I’ve used holly tone in the past and had good results too.

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No it does not and you can make it too acidic that way. It should be checked after a few years though. Natural composting will raise the pH or could.
In containers I use miracle grow for acid loving plants. It is Urea, which blueberries like too. It is only slightly acidic, so doesn’t really change the pH in the container like Ammonium sulfate or sulfur can. I still give them one round of Holly-tone in the spring. The rest of the year I use Miracle grow. In raised beds I use Holly-tone and Jack’s acid which is AS with micros. I prefer well rounded fertilizers to pure AS, even though I have to pay a lot more.
Worm castings are neutral but that is 100 times more basic than 5.0. Fine to use, but realize it may alter pH, monitor it to make sure. This is what I want to avoid with all peat and pine, I don’t want to monitor pH. I have enough things to do.


I use the acid kind of Miracle Gro, too. Or if I know I’ll be too busy to apply so often, I use this:

It’s the one for acid-loving plants. It doesn’t have much sulfur in it at all, so it won’t lower pH much if at all. If I understand the label correctly, it has the kind of nitrogen blueberries can use. Miracle Gro’s definitely does.

Edit: I checked, and it has about half ‘ammoniacal’ nitrogen and about half urea, so it is good there.

Yes for others who don’t know those two forms are what blueberries and I’m sure cranberries (Same genus as BB) like. They don’t like nitrates. The plants can absorb some nitrates, but they have few receptors to do so, and I guess the nitrates can damage the plants too. So you need to avoid them at least in chemical form. I would not be concerned in compost or other weak forms of fertilizer like coffee grounds, or mulch.

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Hoping to revive this old post to get some help with soil for my blueberry plants. In fall of 2022 I constructed new raised beds and filled with a mix of peat moss, pine bark, and a good top soil. I had this soil tested in the spring to see if my ph was low enough for the blueberries. The ph result was 7.0. This was a surprise given the high amount of peat moss and pine bark in the beds. I added sulfur in attempt to lower ph but know it was too late to help the new plants. Fast forward to today (Match 2024) and my plants barely grew at all. Not sure what to do at this point. Add more sulfur or just wait another year to see what happens?

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Holly Tone contains the bacteria needed to convert elemental sulfur into acidic sulfur. Espoma Organic Holly-tone Organic Fertilizer | Espoma
Amonium Sulfate is always an option for a quick fix while the holly-tone takes effect.

You should mention the ratio of each ingredient in your mix. After giving up on growing them in the ground, I added few bushes in container and raised bed with fir bark 50-60% and rest peat moss and they have grown extremely well. You should also fertilize if you haven’t yet.

I wouldn’t rely on added microbes in fertilizers. From reviewing the test reports published by Oregon State 99% of products with microbial additions either contain extremely low fraction on what is printed on the label or doesn’t contain the claimed species at all. A shovelful of good compost should take care of needed microbes, and most soil already contains these common microbes.

I’m a former med tech and worked a lot of lab jobs too. You just need one bacteria. No point in adding any of the sulfur bacteria. They are everywhere. Just add the sulfur.Pelletized sulfur works great and is cheap on Amazon. What’s hard to do Is get the right
Mycorrhizal Fungi for blueberries. It’s not common except where blueberries grow. I found some about eight years ago and when I added it I thought it did make a difference in production. But I can’t really say for sure?
Remember sulfur can take as long as a year to work. At least six months.
You have to monitor pH. You can kill them by getting it too low too. Keep it no lower than four.
For a quick fix your blueberries are in trouble pure ammonium sulfate will quickly lower the pH.

Thanks all for the responses.

@Drew51 - what do you use to monitor the ph? Also, how often do you take measurements?

I like to use these commercial grade plastic strips used for industrial purposes. McolorpHlast is the name. Many other brands are sold too on Amazon. The range i use ( many ranges sold) is 4.0 to 7.0. As all I need to know is that range. Stick the strip in the ground water with distilled water which is neutral. Hydrogen ions in the soil will react to the strip. Works great google the name. I have a link on my computer but all I have is my phone right now. They are super easy to read and tell even fractional numbers like 4.4.
I measure at the start and end of the season. In liquids like tap or rain water just dip and read.
When I said you only need one bacteria is that if one finds the sulfur it will multiply and in a week you will have 50 million. Yes they can multiply that fast.

Remember pH is logarithmic scale. So if ideal is 5.0 and pH is 6 you are ten times too basic. That’s a lot!!