Question
We live where the soil is alkaline, but have raised raspberries with some success.  I have read that coffee grounds help acidify and amend such soils to allow better crops of raspberries and also possibly blueberries.  How much, when, how and how often do you do this?  Thanks

Answer
Coffee Grounds are less acidic than you would think, because the Coffee has already removed a great deal of the acid and raised the pH significantly.

Certain alkaline Soils have no chance whatsoever of ever turning Acidic, simply because of their basic composition.  Not even a daily cup of black Coffee will make a difference there.  If you obtained a Soil Test at some point to diagnose your Soil, I would like to see what type we're talking about.

Meantime, used Grounds are a freebie at Starbucks; a daily dose is a delightful amendment as far as your Soil's biocommunity, as well as a boost downwards in the pH department.  Possibly not much, but every little bit counts.  You may also direct the pH towards the desired reading with leftover glasses of morning OJ and compost composed of citrus Rinds and Pith plus used Grounds.  Bear in mind it is always better to decompose Organic Matter in the Compost Pile; the process of rotting consumes a great deal of certain compounds and could have a negative effect on surrounding growth if applied directly, before decomposed sufficiently.  Hope that makes sense; I'm trying to condense my answer and still be thorough.

Basically, you cannot drink enough Coffee to make a BIG dent in the pH.  But it is still a great idea, and it will only help.

Blueberries may unfortunately NOT be in the cards for you, but that depends on your Soil Test results.  Fill me in.