I do/did both. Started with CSU's BB mix (40% peat, 40% coir, 20% pearlite, IIRC) and also add vinegar to the irrigation water.

This mix ends up acidic enough for BBs as is and does not require any adjustments. My tap water is basic and high in bicarbonates, so I tested the amount of vinegar to bring it to a 5 pH, and use that when watering.

If you are starting with a specific soil mix for BBs or other acidic plants, I don't think you need any further adjustments, at least not at the start.

Thanks. That's kind of my point. Starting with the correct mix for blueberries is important. I do the same as you with the water. My mix is ground pine bark, peat, and perlite. Haven't made any adjustments in the mix in a few years. Having a tough time getting a decent pH reading of the mix. I have a good meter, a Kelway Soil pHD, but it seems to read high. Hard to believe pine bark and peat could read 6.5???? Oh well, the bushes are flourishing, so I'll just keep doing what I'm doing.

I alternate watering with one cup of apple cider vinegar per 5 gallons of tap water which drops the pH to 4.5.

Once a month I use an acid fertilizer instead per directions to water.

The acid fertilizer is really good at maintaining pH. I suspect acidifying the water before adding it is worthless as soil pH is a MUCH stronger buffer than water, but it is inexpensive and acetic acid is a pretty accessible microbial nutrient.

In winter I plan to spread out a couple of teaspoons of powdered sulfur per half barrel container.

I use soil sulfur in the container mix and add organic fertilizer for acid loving plants at least once a month.

I suspect acidifying the water before adding it is worthless as soil pH is a MUCH stronger buffer than water,
I'm struggling with that statement for a number of reasons. There are so many variables at play that understanding precisely where you stand is difficult for me. I suppose at the lowest level, I could agree that a neutral pH volume of soil might be more restive to pH change than a similar volume of neutral water. But then, what does that have to do with acidifying water as "worthless"? Over a year's time, I likely will be adding a greater volume of water to a container than there is volume of media in the container. How is it that the pH and alkalinity of the water being added would be of no consequence (e.g. "worthless")?

There's a fair amount of calling things worthless that seem to work well for others. Some folks have embraced acidifying their water and others have not. Maybe unnecessary in all circumstances might be more accurate/reasonable?

This post was edited by mrclint on Fri, Apr 11, 14 at 14:33

Fascistnation,

I can assure you that the buffering ability of soil be it in the ground or in a pot will quickly be rendered useless with the steady addition of high bicarbonate water. The water will win that fight....it is a never ending addition to the pot or ground for a set volume of media.

Sure you could say well I will just use more sulfur......great but what happens when you hit a few rainy weeks where you don't have to add irrigation water? The PH will plummet . That constant up and down of PH just is not ideal.

Ed,

I guess I just don't understand your question. When you put peat or pine fines in the pot or ground you are adjusting the mixture.

Clint your post on your Emerald is a perfect example of what does not work "well".....the plant survives and produces a couple berries sure but it is not thriving.

This post was edited by bamboo_rabbit on Fri, Apr 11, 14 at 17:53

edweather wrote:
Anybody adjusting the pH of their blueberry container mix?
Regarding the OP question: it’s a bit of a nitpic on my part, but given the clarification I wish to attempt, it is important to point out that any addition of fertilizer, or any addition of water with a different pH than the container media is “adjusting the pH of [] container mix”. Technically, it is impossible to get away from adjustments. Obviously, you were intending the intentional adjustment of pH downward.
mrclint wrote:
Maybe unnecessary in all circumstances might be more accurate/reasonable?
I wouldn’t even go that far. How I would characterize the situation, in part, is: I see two primary modalities by which pH (whether it be a container or soil) can be managed;
A) Adjustment of the media/soil; and
B) Adjustment of the irrigation water used.

Neither are mutually exclusive as many here seem to feel. Any combination of the two can be efficacious if applied properly, from exclusively focusing on the soil, as you seem to do mrclint, and almost exclusively focusing on the water as BR does for his in ground plantings, to any combination of the two. There is a near infinite number of combinations that could produce the same results. And some methods, such as adding ammonium sulfate to water is doing a bit of both (even though the sulfur addition to soil has the bigger role).

I don’t believe it is impossible to add amendments to the soil (elemental sulfur, ammonium sulfate, iron sulfate, etc, etc) in such a manner as to compensate for any alkalinity in the soil/media and/or applied via irrigation. While I personally believe that this is a more delicate balancing act, and the timing may be imprecise causing some fluctuations over a season, it is entirely possible to be successful doing so.

Yet, it is just as viable to adjust and manage the pH of soil/media with water applications. From what I read, most natural soils start off neutral or alkali, and the primary factor by which soil acidification occurs is natural rainfall. The PNW where I grew up has wild blueberries, huckleberries, etc. because the soil is acidic enough for them. The soil is appropriately acidic because of the rainwater that has 1) flushed out ions that would otherwise raise pH, and the naturally low pH of rain (carbonic acid formed as rain falls through atmosphere) being applied.

It isn’t that hard to understand that both methods work via the very same methods if the basics of pH are looked into. One method is applied in one form to one form factor, while another form is applied to the other form factor! The end result is the same. There isn’t nearly as much difference as some tout!

It is basic math of +ions and -ions offsetting each other. Add enough +’s to the soil directly or via the water, it will be sufficient to offset the -‘s, and leave +’s to lower the pH. You add sulfur to your media? Over time that is converted and makes lots of +’s to compensate, and overcome, most (many) existing -'s and most -‘s added via water. You add sulfuric acid to your water? You then are adding lots of +’s to overcome any (most) -‘s in the water and leave an abundance of free +’s, and when applied to the media overcome many/most -‘s there. No matter what modality you choose, it all comes down to adding more +’s than there are existing -‘s!

Mrclint, if adding high pH, high alkalinity water to your pots did not have an adjusting effect, there would be little/no need for you to be adding your handful of sulfur and using ammonium sulfate rather than urea. The mix you made initially per DWN instructions (minus the acidifying amendments) would have a reasonably close pH, and it would largely stay near there. But it doesn’t stay at the original pH. It creeps upward - probably in large part because of your water, and therefore you must add sulfur sources, and from time to time may need to repot in new mix.

Another point that can add to an understanding of this is fruitnut’s recent posting of low pH pots. It is speculated that too much sulfur accumulation and microbial conversion to sulfuric acid, while he treats his water or uses rainwater, allowed too many +ions to accumulate. Pegged the meter down at 3 if I recall correctly. But, to correct that, he added/flushed with 18 inches of well water, and the pH quickly rose. The flushing plus addition of -ions quickly raised the pH.

Unless one is lucky enough to live where the water is naturally 5.0pH or there is adequate rainwater to use only rainwater, adjustment of pH in some way will eventually be necessary. Whether that be ammonium sulfate, sulfur, sulfuric acid, or repotting with new mix, it will be necessary eventually. That’s my conclusion anyway. So almost all of us growing in containers will be continually adjusting our container pH down for blueberries. The difference is the amount of adjustment needed based on how bad your water is and how much water is needed (here in UT, need LOTS more irrigation than in PNW), and the method used to do so (in mix vs in water).

charina, I brought in a bunch of berries this morning and will bring in more tonight and will repeat that cycle into June. My plants will be pest free and I will become weary of picking blueberries by the time May rolls around. In my case acidifying my water is unnecessary.

That's great and entirely consistent with what I typed out about one potential strategy. But you do realize, don't you, that you would have to acidity your water if you were not acidifying your mix? At least would "have to" to have the same success.

Bamboo, I guess what I was asking is how many just put some kind of potting soil in the pot, and try to adjust the pH of the soil to be suitable for blueberries, vs. how many start with a good acidic mix, of let's say pine bark and/or peat, and don't worry about the pH of actual container mix, and only concern themselves with the pH of the water? Or who does both?

In my case, I haven't done any adjusting of the mix, it's the same ground pine bark and peat I started with 3-4 years ago. All I do is adjust the water to a pH of 4.5-5 or so.

That's the way I do it too Ed.I may renew the mix in 3-4 years. Brady

charina, gotcha. You are correct, the acidification has to come from somewhere. Cheers:

I do both right now. As I have some sulfur. But I think in the future I will adjust PH with sulfuric acid. It seems easier to me, and has immediate results. Adding elemental sulfur is a guessing game.
My soil is finally warm enough to get a good test. And my raised beds tested at 6.0. I was shocked how much the PH rose over the winter! I think it is because of a lot of decaying matter in the mulch etc. So being the start of the season, I want to get that PH right quickly! The only way I can think of is to water with sulfuric acid. I'll adjust water to 5.0 and check PH of soil weekly till it is down. As soon as growth starts I'll hit them with a good shot of Ammonium sulfate. I'll stop and just use pure rainwater when PH is right. But I will keep testing soil weekly. My rainwater is not acidic it is neutral. I may have to keep adding sulfur for a long period. Not sure? Will monitor.

Ed,

Gotcha. Thank you for the clarification.

Clint,

"I will become weary of picking blueberries by the time May rolls around"

Seriously do you expect us to believe that? You have 4 stunted bushes, your production has to be about 8 pounds MAX. You have already stated that you have to repot your blueberry bushes constantly to deal with the PH issues. That is not a system that is working well. Compare that to Steves potted plant yielding 18 pounds of fruit and not needing repotted for 7 years.

edweather, you bring up some good points. Most folks don't do their homework and fail to start out with a proven mix for blueberries,

I never acidy my water and live in a very hot and dry climate. In the summer I put two or more gallons of water on my plants several times per week. The ph of my soil is too low! I started with peat and soil and fertilized with ammonium sulf. My water is well water and I'm guessing ph is above 7, have never checked it. Point is, it may not be necessary to acidify your water. My plants are starting fourth year. Some may need to acidify, some may not.

RM

I have high PH and high Alkalinity water. Here is some information about irrigation water changing soil.

(My Two Cents Worth Be aware that peat is very low PH. Commercial mixes have added lime and that lime breaks down which can lead to a sudden drop in PH in pots. I saw one site for commercial greenhouses that recommended amending water only if the water was over 80 parts calcium carbonate -alkaline)

From Most Extension Sites:
"water with high alkalinity (i.e., high levels of bicarbonates or carbonates) always has a pH value ÷7 or above, but water with high pH doesn't always have high alkalinity"

"In most cases irrigating with water having a "high pH" causes no problems as long as the alkalinity is low"

" (very alkaline water) "One result is that the pH of the growing medium may increase significantly with time. This increase may be so large that normal lime rates must be reduced by as much as 50%."

"In effect the water acts as a dilute solution of limestone!"

"The problem is most serious when plants are grown in small containers because small volumes of soil are poorly buffered to pH change. "
C/P quotes from Mass Amherst Greenhouse

I am considering phosphoric acid since my water is well over 8 PH and more than 80 calcium carbonate alkaline. Any thoughts about whether that is a good acid to use?

Here is a link that might be useful: Mass Amherst Greenhouse

This post was edited by lucky123 on Sat, Apr 12, 14 at 18:55

I wouldn't acidify at all until you go through a season to see what happens. Again, I pour the water to my plants and the ph is effected very little just as the information you posted above suggests. The summer temps here are 90+ from mid June through September, it's hot and I put a ton of water on and my ph is too low so I'm currently using Urea instead of ammonium

Try irrigating for awhile, watch the ph, if it becomes a problem then adjust your approach.

RM

I pour the water to my plants and the ph is effected very little just as the information you posted above suggests
1) You ought to reread the information presented by lucky123. In regards to non-acid loving plants, it states:
Of greater concern is the case where water having both high pH and high alkalinity is used for irrigation. . . . One result is that the pH of the growing medium may increase significantly with time. This increase may be so large that normal lime rates must be reduced by as much as 50%. In effect the water acts as a dilute solution of limestone! The problem is most serious when plants are grown in small containers because small volumes of soil are poorly buffered to pH change

2) How do you conclude it has "very little" effect? The effect may be extremely large, but simply counteracted and overcome by the amount of acid being produced through your other cultural practices. What have you done to measure to support the idea that “the ph is effected very little”? FYI, your current pH is a very poor indicator of the size or nature of the effect, only an indicator of the net effect of multiple inputs.