Aluminum Sulfate for Blueberries

glenn_russell(6b RI)January 3, 2009

Aluminum Sulfate for Blueberries

I planted 5 dwarf blueberry plants (Chippewa & Friendship) last year on a recently filled area of my yard, and they seemed to do fine. I plucked the 1st year berries off early (as hard as it was to do), and they are in a mostly sunny area of the yard. IÂd estimate them to be about 2 feet tall. There is loam on top of the fill, and last time I checked it, the soil was slightly acidic, but only slightly. (Unfortunately, I donÂt remember what it was right now if I had to guess, I had some other fill/loam areas nearby which were around 6.5. IÂd check it, but the ground is frozen with a couple inches of snow on top). I also mixed in a good amount of peat moss when I planted them. I have a couple other blueberries in other areas which IÂve never attempted to modify the soil, and they seem to do just fine though I think I gave them a tablespoon of Miracid or two. Nice big blue berries on my Blue Crop last year, and lots on them though I had to make a big PVC and bird netting cage to keep the birds off them.

Anyhow, I meant to start dropping the PH last year, but never got around to it. I have a bag of Bonide Aluminum Sulfate 0-0-0 here that I havenÂt yet opened. The package says its best used in early spring, but I had thoughts of applying it sooner to get the ph-lowering process started sooner (on a warmer day when the ground is soft, and no snow on the ground) because I know you want to change the PH slowly. Is there any harm in applying this in the winter? The package has an application rate for a ph of 6.5, loamy soil of 2.75 cups per 100 sq feet. IÂm guessing these dwarf plants have only a couple of square feet to them, so IÂll say 4 sq feet each. So, I calculate that to be .11 cups, or 1.76 tablespoons per plant.

I want to get this right because IÂll be adding quite a few more (non dwarf) blueberries this year.

So, any harm doing this during the winter? Does 1.75 tablespoons per plant sound reasonable? If I add the aluminum sulfate, should I not give them any Miracid this spring? Anything else I should consider? Thanks as always,


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fruitnut Z7 4500ft SW TX


I'd chuck the AlSO4 in favor of sulfur. I've never heard anything good about the former and everything good about the later. But I won't go overboard with either as long as your plants look good. Soils in your area should be naturally acidic. The only advantage to a really low pH is weed control, some weeds won't grow at pH that blueberries tolerate.

I found out what blueberries look like when the pH is too low this last summer. Did this by applying sulfur to potted plants. Within a week or two the new leaves showed damage in the area of the leaf veins. After flushing the pots with high pH well water the new growth returned to its usual healthy state. I regularly fertilize these plants with ammonium sulfate so I've concluded that the pH is low enough just from that.

The Fruitnut

    Bookmark   January 3, 2009 at 3:26PM
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I too don't like the idea of the aluminum and won't use it anymore. Soluble aluminum is quite toxic to plants (though not blueberries) and the jury seems still to be out on its effects on humans. Its advantage over sulfur is that it is more powerful in lowering acidity. So simply use more of the cheap innocuous sulfur.

    Bookmark   January 3, 2009 at 4:04PM
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Cottonseed meal and a good mulch of pine needles or pine bark works great for me

    Bookmark   January 3, 2009 at 6:13PM
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"Cottonseed meal and a good mulch of pine needles"

That's really what I mainly use too, on rabbiteyes, plus some oak leaves when convenient and occasionally some foliar iron spray as well when I'm already feeding other plants (iron sulfate or chelated iron).

    Bookmark   January 3, 2009 at 7:05PM
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glenn_russell(6b RI)

Hi All-
Thanks for the info. I had originally asked for Sulfur, and my nursery said to use Aluminum Sulfate. I'll return it and see if they have any sulfur, or find it elsewhere. Yeah, I wish I had pine trees more for my strawberries than the blueberries. Unfortunately, I have many fruit trees now, with not too much room to add some pine trees. There are none growing natively on this lot. Anyway, thanks as always.

    Bookmark   January 3, 2009 at 8:24PM
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glenn_russell(6b RI)

Hi All-
Ok, back to this thread. I've now obtained my Espoma Garden Sulfur, but I'm really not sure how much to add. According to my little hand-held ph meter (which I'm not sure if I can trust or not), my PH is supposedly at around a 7 right now. From what I remember about chemical soil test I did last year, they read more like 6.5. The table on the back of the bag is lbs per 100 sq feet. But, I want tsp/tbsp per plant. Anyone want to take a guess at how many tbsp of sulfur I should add for these blueberries? IÂm thinking my planting area is around 4 sq feet per each small plant. Thanks, -Glenn

    Bookmark   March 15, 2009 at 3:30PM
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austransplant(MD 7)


I bet your garden center person confused Aluminum Sulphate with Ammonium Sulphate. Ammonium Sulphate is a common fertilizer for blueberries and will help serve to acifidy the soil and provide nitrogen.

    Bookmark   March 15, 2009 at 3:37PM
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thisbud4u(San Diego)

I've done some experiments with elemental sulfur and with various salts of sulfur, including aluminum sulfate, iron sulfate and ammonium sulfate. Here's the results:

1) Elemental sulfur will lower the pH very nicely, but very slowly, over a period of months. I just add a handful per plant. You CAN add too much and burn the plant, but it acts very slowly, so you have a little latitude for the amount you add. Better to add smaller amounts at regular intervals. Where I live, the pH of the water the city gives us is above 7 and the soil is pH 7.5, so it's a constant battle just to keep the pH low enough for blueberries.

2) The salts of sulfur will lower the pH immediately, like within thirty seconds (no joke I timed it with pH paper), BUT they can much more easily burn the plant as a result. Personally, I'd never use aluminum sulfate, but iron (ferrous) sulfate and ammonium sulfate are OK to use. I prefer ferrous sulfate, because blueberries also like the iron, but you can use ammoniuim, remembering that you're also adding a high dose of nitrogen when if you do use the ammonium sulfate. In my experience, blueberries prefer their nitrogen in more organic (slower release) forms than ammonium.

Hope this helps,

    Bookmark   March 15, 2009 at 3:42PM
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glenn_russell(6b RI)

Hi thisbudforyou and austransplant-

Thanks for the infoÂ

I decided to take a picture of one of the plant as maybe it would help people estimate for me. Below is my Gatorade plant. :) Ok, actually, Gatorade was just added for scale. Like I said, the plants are pretty small, planted in an eye-shaped planters to facilite mowing. Planted as bare-root last year. Hopefully new shoots will begin to come up soon. IÂll give it a bit more mulch soon as well.

So, IÂm still not sure if I have an amount here. "handful" could mean different amounts to different people. (My hands are pretty big) On the sulfur label, there were talking about amounts of 1 tsp  a few tbspÂs. Care to take a stab at a tbsp amount?

Also, is time of year OK? As you can see, the plant hasnÂt woken up yet. Though weÂre probably starting to get close I did see the first signs of life on my raspberries today as I gave them their yearly compost.

I'm sure in the future I won't need to be so precise with my sulfur measurements. It's just that I've never used it before so I don't know if I should be thinking about amounts like 1 tbsp, or 1 cup!

Thanks as always,

    Bookmark   March 15, 2009 at 4:52PM
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juniorpilot(USDA 10 Suns 20)


I have four different varieties of blueberries in 18 inch pots. These are big pots. I'll estimate (roughly) they hold 24 gallons by comparing them visually with the volume of a 15 gallon pot.

I put a small handful of elemental sulfur into each pot twice a year, once in the spring and once in the summer. I'll estimate this small handful is 4 to 5 tablespoons. Additionally, and at the same time, I add another small handful of organic Azalea/Camellia food to supply nitrogen.

This regimen, which I don't strictly follow, keeps my blueberry soil in the pots at about pH 5.5. My blueberries do well. Nice growth and lots of berries.

Open ground soil is a powerful buffer. That is, it can absorb and negate the pH effects of things we add to alter the pH. Potted soil provides far less buffer than open ground soil. So my opinion is that you have a sizeable latitude in the amounts of sulfur you add to your soil.

I am going to go where angels fear to tread and say that 5 tablespoons of elemental sulfur evenly spread in an 18 inch diameter circle around your blueberry plant is a safe starting point. As thisbud4u pointed out, it takes longer for elemental sulfur to act. So you may not see a change in pH reading for a month or so. The plants themselves may respond within two weeks, one way or another, as fruitnut pointed out. I had a similar experience when I first started with blueberries in that I had leaf burn (not severe) within three weeks when I put a big handful of sulfur and a big handful of Azalea/Camellia food in the pot.

With this 5 tablespoon amount, I think you should see a slight change in pH within a month or so. And you can build from there with your own experience.

His (thisbud4u) post is very informative. I think it is worth reading a couple of times to absorb what it has to offer.


    Bookmark   March 16, 2009 at 2:02AM
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glenn_russell(6b RI)

Thank you for info! 5 tbsp is about what I was thinking, and it seems to be similar to thisbuds4you's handful, and similar to what I would have expected based on my other searches. I think I'll start with about that much. Yes, I planned on giving them a little Miracid one they started waking up. (I think it's ok to give the sulfur now because it's not really a fertilizer, just a PH lowerer, right?) I didn't give them the miracid last year because they were newly planted. Thank you for all the info!

    Bookmark   March 16, 2009 at 8:54AM
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Did you use an acidic potting mix, as well? I'm curious because my personal experience has been that you'd definitely run the risk of dropping the pH too low if you added that much to plants in a 1/2 peat potting mix. However, my mistake was compounded by mixing the sulfur in with the already acidic soil, so I think the fact that you put it on the surface (where it is gradually absorbed) makes a big difference. In any event, it sounds like your system is working for you.

Glenn, I think that 4-5 tbl's widely spread on the soil surface for non-potted plants would probably be fine However, if you mixed half peat in with your soil, I'd wager that you'd also be fine with less (or just do a wide perimeter to antipate when the roots grow out of the peat enriched soil, which is what I did for my outdoor plants). Based on my past loses in sulfur treated pots I've adopted harvestman's "add a dash, wait, and test, then repeat if needed" method for acidifying soil.

    Bookmark   March 16, 2009 at 10:23AM
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glenn_russell(6b RI)

Hi djofnelson-
Thank you for the 2nd opinion. That's why I figured I'd give others a time to respond before actually doing it. Sounds like I may want to reduce it just a bit. Yeah, I like the idea of moving gradually, but at the same time, with such a wide gap to jump, I was a bit nervous that I would be 1/2 way through the summer before I made any progress. Thanks as always,

    Bookmark   March 16, 2009 at 11:01AM
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Do you have any idea what your starting pH is? Also, any idea whether your soil is sand, loam, clay (or a mixture, I do hope!) It makes a difference in how much sulfur to add. Sandy soil is much easier to adjust than clay is.

Here is an illustration based on my own experience. Last year I planted eight blueberries in a prepared bed of approximately five feet by fifty feet. Our soil pH is up around 8 or 8.5, very alkaline. It is a sandy clay. I dug in eight cubic feet of peat, four cubic feet of fine bark mulch, a generous amount of garden compost, and ten pounds of elemental sulfur (two five pound boxes). Then I planted my blueberries. Five of them thrived, two just sat there, and one died. The one that died may have been a watering problem. I checked the pH in that bed a month or two ago and found it was 7. My plan was to continue adding sulfur a couple of times a year to slowly bring the pH down lower over time.

I have just finished moving my blueberries to another, similarly prepared bed for watering issues . Fortunately some of the southern highbush blueberries (South Moon, Sunshine) can tolerate pH variance a bit better than other blueberries can. I'm pretty confident that this can be made to work. I have seen blueberries thriving in several gardens in our alkaline soil area. If certain varieties don't do well for me, I'll simply replace them with others that do.


    Bookmark   March 16, 2009 at 11:36AM
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Glenn, one other thing I meant to mention is that if you're using the same cheap $20 pH metter that I am, make sure the soil is saturated with water before taking a reading. The package says this, but I missed it the first time (I'm sure you're probably better at reading instructions than I am...). Also, you can stick the probes in vinegar to make sure it actually works (i.e., batteries aren't dead, or it hasn't become miscalibrated) because around 6.5-7 is the default location of the needle. White vinegar usually has a pH of about 2.4, but even if it varies, you'll at least get a rough calibration.

    Bookmark   March 16, 2009 at 12:30PM
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Here in Madison, Wisconsin, we have hard water, that contains dissolved limestone. I think our native soil is also slightly alkaline, due to the limestone. I have been growing blueberries since 1994. When planting a new shrub, I dig out the hole, & put in one cup of granulated soil sulfur. This is a somewhat chunky material, not a fine powder. Then I put one half of the dirt back in the hole, and mix with the sulfur. The remaining dirt is amended with either peat moss or compost. We have soil that is relatively high in clay. Our blueberry shrubs are fertilized with Miracle-Grow, acid formula, every spring. When it is necessary to water the shrubs with tap water, I have to pre-treat the water with white vinegar, to lower the pH. I have found that soil sulfur takes at least one year to dissolve. I use a calibrated glass bulb type pH meter to check soil pH.

    Bookmark   March 16, 2009 at 3:45PM
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Ericwi, that sounds like a good compromise between getting longterm acidity without risking overdoing it.

I should have added that I've got fairly heavy soil (a somewhat loamy red clay) with a pH of around 6.5. I might try 1/2 cup of sulfur in the bottom of my next blueberry planting hole.

    Bookmark   March 16, 2009 at 4:57PM
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ajpa(z6 se PA)

I'm another newbie. I just added some Espoma garden sulfur to where I am going to plan 3 BB's. I had a soil test done last fall which says the pH is 5.8, and they rec'd what amounts to 2.9 lbs ground sulfur per 100 square ft, but with instructions to only apply half of that, and another half in 6 months after testing.
I worked that out to approx 5.5 teaspoons per 4 sq ft (2x2 area).
We just got the grass off this weekend and I put the sulfur on today. I've covered the area up with black plastic for now until I can get something over the soil (peat moss/ some kind of compost/mulch).
Here's my q: The whole bed is 12x4, but the BB's are only going into 1x1x1 holes, right? So, to save money, can I spread a thin layer of peat/compost/mulch over the whole bed, then a higher layer on the spots where the BBs will go?
Sort of a raised bed with little mounds, I guess? Good idea or bad?

    Bookmark   March 16, 2009 at 6:56PM
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I've put my 2 cents in before and will again on blueberries. Instead of using chemicals, I find the best acidifier for my blueberries has been using lots of oak leaves as a mulch.
The neighbors thought I was crazy,,, They are out raking leaves and I'm hauling those leaves over to my blueberries. Finally I said, save those garbage bags and just use my wheelbarrow. It works, it's organic, and it's cheap.

    Bookmark   March 16, 2009 at 6:57PM
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If I was able to irrigate our blueberries with tap water that was of neutral pH, I think I would be able to get the soil pH right without using chemicals like granulated sulfur and vinegar. Peat moss is supposed to lower soil pH slightly, and I suspect that compost made with oak leaves would also lower pH. However, given our tap water heavy with dissolved limestone, it has been necessary to get into chemistry to successfully keep these shrubs green and healthy.

    Bookmark   March 17, 2009 at 11:24AM
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I think I may have OVER sulfured my blueberries this Weekend, but I am not even sure I obtained the right Product When I stopped by my AG Supply store on my way to my plantings this weekend and asked for sulfur the provided a 50 LB bag of sulfer as a wettable powder, when I asked how much to use on my bushes most of which are about 3 foot and fairly well bushed, He stated about 4 cups spread around each bush, My plantings are not at my residence, and I had no manner to check here to elsewhere and I applied that amount to each this weekend, that was followed by a pretty heavy rain. It spoke of above on "burn" Is it like a nitrogen burn, and is sulfur a N value, as I know blueberries do not like heavy N , I will not be able to check on them for 2 weeks should I expect damage from 4 cups of this product listed below, I really have concern this morning on reading this and other posts.
Trade Name & Synonyms: Yellow Jacket Flowable Sulphur, EM 70
Chemical Name: Sulfur
Family Name: Element - Sulfur
Chemical Formula: S8
Appearance: Creamy pale yellow liquid
CAS Number: 7704-34-9
Hazardous Ingredient: Sulphur
% by Weight: Flowable Sulfur 53%, Fluid Sulfur 70%
Appearance: Creamy pale yellow liquid
Odor: Sulphur odor, or faint odor of rotten eggs
Purity: 52%, 70%
Formula: S8 (Rhombic or monoclinic)
Vapor Pressure: Solid: 0.0001 atm Liquid: 0.0014 atm
Solubility In Water: Disperses to form an emulsion
Specific Gravity: 1.30, 1.5
Boiling Point: Not available
Freezing/Melting Point: Not applicable
Bulk Density: 11.4 lbs. / gallon, 12.9 / gallon

    Bookmark   July 13, 2009 at 10:14AM
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Sulfur is used as an anti-fungal agent on certain crops, I think cherry and peach trees are among these. The procedure involves mixing powdered sulfur and water into a slurry, which is sprayed onto the branches of the tree. Granulated sulfur is more commonly used as a soil amendment. The particles are about the size of an oatmeal flake. Granulated soil sulfur takes about a year to be broken down by soil bacteria, and converted to sulfuric acid. That is, it will take a year for the visible particles of sulfur to disappear. Since granulated soil sulfur takes longer to dissolve, the chances of burning the roots of a plant are reduced, when compared to powdered sulfur. I can't say whether or not you put down too much sulfur on your shrubs. If you have highly alkaline soil, you might be OK.

    Bookmark   July 13, 2009 at 11:46AM
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I have enjoyed the above ideas. I have 15 blueberry bushes in Highlands, NC, Zone 6, about 4000 feet. Hardly any berries,,,,,checked my PH which is 6.5. I know 5.0 is the max, but all the thoughts above make it hard for me to zero in on vinegar?,,, or Sulphur or amon Sulphate? lower my PH. Can you tell me what is the best procedure for me at this time??? Many thanks

    Bookmark   March 18, 2013 at 3:18PM
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Agricultural sulfur, applied to the soil, is metabolized by bacteria, and very slowly converted to acid, over a period of months. It can take 24 months for the process to be completed, depending on warmth and soil moisture. This is likely the least expensive way to lower soil pH, but it does take time. An application of water soluble ammonium sulfate will lower soil pH in a few seconds. If too much is applied, the plant will be damaged or killed very quickly. However, ammonium sulfate also supplies nitrogen to the shrub, so it acts as a fertilizer, as well. Vinegar, mixed with water, can be used to lower soil pH, but the vinegar disappears within a few weeks, so the effect is temporary. If a plant has yellowed leaves due to high pH, then a vinegar/water solution will give some immediate relief, so it can be useful in that situation. I personally use agricultural sulfur to lower soil pH around our blueberry shrubs. I might add 6 ounces by volume every three years, but only after I have tested the soil pH, to see if more sulfur is really necessary. It is possible to kill a shrub with too much sulfur.

    Bookmark   March 18, 2013 at 6:19PM
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I agree with everything that eric had to say. Just let me add, it is hard on the plants and the soil ecosystem to make rapid changes, so I only resort to adding vinegar or sulfuric acid if the plant looks like it is already going to die. Then what can it hurt? If there is only mild yellowing, you can also try iron sulfate, it lowers the pH quickly and also adds iron, not as good as chelated iron but it helps. Test the soil annually and adjust slowly. We also get a leaf analysis done mid-summer, that is the real test of what the plant needs.

    Bookmark   March 19, 2013 at 8:54AM
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