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I'm working on the right composition of planting mix for blueberries in a high pH environment. In addition to a regimen of ammonium sulphate + sulphur I'm thinking to start with a soil, sphagnum peat moss and pine bark mix. But I need to be sure I get the right kind of "peat moss."

Iowa State makes the following statement:

However, most peat moss found in garden centers is neutral or slightly acidic. Only Canadian sphagnum peat moss has a low pH of 3.0 to 4.5 and will effectively reduce soil pH.

This raises a warning flag, to be sure I'm getting the right product.

My local hardware (Menards) carries Premier brand "Sphagnum Peat Moss [Tourbe de sphaigne]" which does not use the word "Canadian" but is labelled at the bottom as a "Product of Canada." But Menards also sells a much more expensive "Peat Moss Canadian Sphagnum" by Schultz which does use the adjective "Canadian." Are these the same thing (e.g. both 3.0 - 4.5 pH)?

Does the fact that the Premier product comes from Canada mean it's this lower pH product Iowa State is referring to? I ask because I don't recall ever seeing any other kind of peat moss in hardware stores, so wondering what the "*most* peat moss found in garden centers" is actually referring to. I want to make sure I don't buy a higher-pH product at the bulk I need.

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I ended up buying a single unit of both these products and several other peat moss products from various stores, and pH testing them (at home, not professionally). Here are my results:

Miracle Gro Sphagnum Peat Moss - ph 5.0
Greensmix Sphagnum Peat Moss - ph 5.0
Premier Sphagnum Peat Moss - ph 5.5
Schultz Peat Moss Canadian Sphagnum - ph 8.5!!!

I double tested them all, so while my numbers may be off due to color matching, they are definitely meaningful side-by-side. Clearly, Schultz' product is strongly alkaline and would be a sad surprise to anybody adding it to their blueberries!

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