Hi Janos, My apologies for the misspelling of your name. Where I have seen them growing naturally in Northern California, they seem to receive much organic material in the form of fallen leaves and debris, so I suspect they prefer acid soil. My own backyard soil is fairly alkaline, which they seem to tolerate, although I did add some organic material at planting 8-9 years ago. Mine also may receive benefit from the fallen leaf litter of adjacent growth, most of which I leave in place. In zone 5 you may wish to mulch heavily in Autumn, to protect from extreme hard Winter freezes, removing some or most of it when growth resumes in Spring. Ken Blackford San Diego, California USDA zone 10 ... Do they need acidic soil? Janos