Are the plants in the ground or in pots? Mixing peat moss into the soil will lower the pH pretty quickly. Adding garden sulfur is easier, but it takes several months for the pH to drop. I'd use sulfur, and make sure the plants are mulched with some kind of organic mulch, like compost or wood chips. As long as there is a lot of organic matter on top, the pH is not so critical to their survival, although they may not produce well until the pH is lower. You can find bags of sulfur at a lot of garden centers. I also see it at Home Depot and Lowes in the garden section with the garden fertilizers. Directions on the bag will tell you how much to use. Alex

There are many things that determine what a soils pH will be, and all have been clearly laid out here by several contributors. What the soil is composed of, rainfall, and amount of organic matter all play a role in how many free Hydrogen ions are in that soil and soil pH is a measure of that. What is needed to change a soils pH depends on where it is and what is meant to be done. Adding lime (Calcium Carbonate) will reduce the free Hydrogen ions and raise the soils pH while Sulfur adds more of them and lowers the soils pH. A good reliable soil test from a good soil testing lab is a good source of information and they should be able to tell you how much Sulfur needs to be added to make the needed changes. Adding 1 pound per 1,000 square feet when 10 pounds is needed will not do much of anything. Throwing a handful or three of something is more a waste of time, money, and energy than any help. Here is a link that might be useful: understanding soil pH

I think that the difference in buffering capacity of the soils in question is the reason that people see different results and disagree on this topic. Here is an example of how buffering capacity of the medium will affect pH changes. Assume we have two different 100 gallon tanks of water. Tank number one is pure distilled water. To this tank we add a few drops of sodium hydroxide to raise the pH to 8.5. Tank number two is water drawn from a well with very high levels of minerals primarily consisting of calcium (Ca2+), and magnesium (Mg2+) metal cations ("hard water"). This water measures a pH of 8.5. Now we have two tanks of water that both measure pH at exactly 8.5. But both tanks are not created equal! "Think; two different gardens, both with pH 8.5 soil" We want to lower the pH to neutral so we will need to add an acid to both tanks. Tank number one will only need a few drops of hydochloric acid to lower the pH to neutral, while tank number two may require 100x more acid to become neutral. The reason for this difference is the buffering capacity of tank number two due to the high levels of calcium and magnesium metal cations. This has been my hands on experience from hydroponic gardening and I believe that the same chemistry applies to acidic soil amendments such as peat moss. Therefore, depending on the specific soil buffering capacity, gardener number one may require only a small amount of peatmoss (by volume) to change the pH of his soil from 8.5 to neutral, while gardener number two may require vastly larger amounts. Here is a link that might be useful: My soil test, oh happy days..... not

I grow blueberries both in the ground in raised beds (5 plants in the ground for five years) and in sturdy black plastic plant containers (5 plants in 4 to 7 gallon containers)--that I picked up cheap from a local nursery. Two years ago, I harvested over four gallons of blueberries. Last summer the container plants were a bit of a bust as a late 90 plus heat wave after I'd cut the watering back resulted in the container plants having a very poor crop, but I still harvested nearly four gallons of berries from the plants in the raised beds. They are picked and put into gallon freezer bags and popped into the chest freezer. I don't even wash them, as I use no pesticides on them. I removed my clay soil in 2'x2'x15" deep sections and built the beds up to about six inches above ground level with a mix of 3 parts sphagnum peat moss, 1 part leaf compost my town produces, and 1 part of the clay topsoil. I reused the rest of the clay in another part of my garden. The container mix is simpler: 2 parts sphagnum peat, 1 part leaf compost. The beds have not needed additional soil or peat in five years. I mulch the beds with pine needles (not for the acidity as they don't actually contribute any, but for the fact they contain no weed seeds to speak of). I use bark mulch as a mulch in the containers--it stops squirrels from digging in them and weeds from growing. I use drip irrigation with city water at a pH of about 6.5 or so, and fertilize with Ammonium sulfate every spring, which also keeps the acidity level up. Fafard makes a sphagnum peat moss based acidic soil mix, so that's an option if you can get past the sphagnum peat moss issue. If you're only growing enough blueberries for you and your family, you are not really going to need a lot of the stuff. It's worth noting that for every person who thinks sphagnum peat moss is not a renewable resource, there's likely another who thinks the opposite is true. Here's what I know: In the US, our ubiquitous Canadian sphagnum peat moss comes from a country that has a lot of it and only harvests a small amount of it, and reseeds the harvested areas with ... sphagnum peat moss, which in the university greenhouse collection I help maintain grows quite quickly--I frequently have to cut it back to keep it from overwhelming our carnivorous plants that grow with it. In North American bogs, the moss grows several or more inches a year. The harvested bogs won't be replenished soon, but they aren't exactly turned into parking lots either. Then too, the harvesting process is not very carbon intensive in the scheme of things. You can read more about this perspective on the topic here: http://www.theecologist.org/blogs_and_comments/commentators/other_comments/1780209/the_truth_about_peat_moss.html and here: https://garden.org/urbangardening/?page=august_peat