Last year I planted three 1-year-old blueberry bushes in my back yard in clay soil and I've added several inches of mulch and soil amendments, but have a feeling that they won't do well in clay soil long term. If I keep adding organic material/mulch and work on the acidity with amendments, could they do well long term? Or should I make plans to transplant them at some point? Is clay soil too compact for blueberries to do well? I was thinking of moving them into a mound of sandier acidic soil? -- I'm in (Minneapolis, MN USA) Zone 4 for reference.
You should fertilize and acidify soil every year. On a clay soil, acidophile plants have more difficult to get nutrients.
I'm not happy also with my blueberries (also on clay soil). Having made a huge hole, and filled with peat allowed me to have many blueberries, but the same plants on an acid soil should have give me a huge amount of them. But it seems that they can still give my blueberries on long term.
I'm still thinking if a very large pot were a better solution.