I grow all my blueberries in containers and use this mix (per 7-gal of soil):
2/3 pine bark
1/3 organic top soil
1.5 Tbsp powdered elemental sulfur (99-100% grade)
1 cup worm castings
1 cup holly tone
Works great for me. Soil pH is 4.4.
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If Iām planting directly into this mix without waiting and want to make sure pine bark doesnāt tie up the nitrogen in the soil, I add:
ā 1 Tbsp blood meal (fast release nitrogen)
ā 2 Tbsp feather meal (slow release nitrogen)
Not sure if itās 100% necessary but it hasnāt hurt. All my plants are doing great.
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I have rabbiteyesā¦ 7-8 ft tall, 4-6 ft wideā¦they produce gobs of berries.
They are quite happy with Ph of 5.5.
I fertilize in early spring (around bud swell) with hollytone.
Then late july when last berries are harvestedā¦ i give each bush 2.5 gal of high N miracle growā¦ I do that a couole times a week or two apart.
They put on some nice late summer /fall growth. I have a long season hereā¦ my late summer / fall growth does not suffer winter dieback.
Without that summer high N feeding my bushes put on very little new growth.
TNHunter
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do you know what else they are fertilizing with? doing that would mean you would need yet another custom fert for the rest of the nutrients unless you wanted crazy amounts of N. if you were to add a osmocote dressing, for example. this is the breakdown of ammonium sulfate:
otherwise i was thinking of the sulfur prills.
ive also found pelletized gypsum very inexpensive locally. which is calcium sulfate. the sds on that:
looks like gypsum might not work at lowering ph:
If soil tests indicate Ca is needed, soil pH is nearly always too low as well. Apply limestone or dolomitic limestone at recommended rates (usually 1,000 to 2,000 lb/acre). Occasionally Ca levels may be low when pH is in the proper range. Gypsum is a good Ca source in this situation because it does not change pH.
Soil pH
Unlike lime, gypsum has little if any effect on soil pH. Lime raises pH due to the reaction of carbonate (CO3), not Ca. In extremely acidic soils (pH below 4.5) that contain high aluminum levels, gypsum may increase pH slightly. The chart below illustrates this effect. We applied annual applications of calcitic lime (1,000 lb/acre) or gypsum (500 lb) to a very acidic blueberry soil. Gypsum clearly increased pH, but not nearly as much as lime. If the initial pH of this soil was 6.0 or 7.0, gypsum would likely have had no effect on pH.
Since last year I started using Jackās acid water soluble fertilizer once a week from April until mid June for my Blue Berries in pots and raised bed and have gotten great results. For the rest of the season I use Down to Earth Acid mix.
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is there a risk using this type of N to dial in the PH by overdoing it on N?
Yes,like any fertilizer,too much can be harmful,like burning the roots.@fruitnut did some experimenting with potted Blueberries,using small amounts of Ammonium Sulfate and achieved remarkable growth.
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do you have a link to these posts by chance?
@fruitnut,were your results,using Ammonium Sulfate and Blueberries,on growingfruit.org or Garden Web(Houzz)?
Iām not sure. But Iād guess it was before growing fruit. I remember when the guy that later started ourfigs came on board at the gardenweb. He was big into blueberries at that time. I was also.
For purposes here though,I seem to recall your fertilizing schedule for them was near to once a week,or when watering was needed.The amount of AS,being something like 1 teaspoon per 2 gallons of water.Is that about the ratio?
@kinghat, regarding blueberry fertilization, this site: Growing Blueberries in Your Home Garden | OSU Extension Service states that blueberry bushes usually donāt need anything except nitrogen fertilization; and it provides guidelines for the amount of nitrogen to apply to plants of different ages. I normally apply a small amount of Rhodo and Azalea fertilizer in early spring and then apply 21-0-0 in the recommended amounts in April, May, and June.
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i was about to order ammonium sulfate on amazon but found that lowes has a 40lb bag for $25 which is waaaay cheaper. maybe its even cheaper elsewhere 
https://www.lowes.com/pd/Sta-Green-All-Season-40-lb-10500-sq-ft-20-0-0-All-purpose-Lawn-Starter-Fertilizer/5013506421
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Yes,thatās one of the pluses about it.
They may not need it but Iāve noticed it does make a ton of a difference.
The non fertilized periodically ones Iāve had are having a lot less flower set than the ones i got earlier last year and was on a good fertilization schedule.
I use acid loving fertilizer and Jackās fertilizers
That sounds about right.
Ammonium sulfate is 21-0-0. The 20-0-0 has 24% sulfur. Somehow that seems off. If itās actually 76% 21-0-0 then it should be about 16-0-0. Donāt understand that but itās not an issue. Something with 24% sulfur isnāt an all purpose fertilizer. It might be good for blueberries on a soil thatās naturally too high in pH. Even there the rate will be important.
Surely you can find real ammonium sulfate, 21-0-0 without the sulfur.
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I use Miracid in the spring at bud swell as well (think Iām going to try Urea this year). My soil is best described as bolder/clay, its got a naturally low pH (~5.5) but the blueberries seem to like it a little lower. When I prep a blueberry bed I add organic matter (woodchips, sawdust, pine needles) and sulfur. I usually put down a layer of cardboard and more mulch. I donāt think any mulch (including pine needles) effects the pH if the soil is already below 7, but the shallow roots of the blueberries plant need that thick humus that my soil lacks. My biggest issue is not enough nitrogen (go figure with all that mulch)ā¦ but late season nitrogen (for me) leads to a boom in fall growth and then frost damage.
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i thought the same thing was weird but all of the ammonium sulfate 21-0-0 ive run across, even amazon, has 24% sulfur. i thought it was counted for when then ammonium and sulfate split 
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You probably have that right. Itās not a mix of elemental sulfur and ammonium sulfate. Theyāre getting 24% sulfur from the sulfate in ammonium sulfate.
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