
I have heard that hügelkultur beds are not great for perennials. Because of the rotting wood, the soil level will drop 1-2 inches per year. For some perennials, that would be a disaster. I watched a video of a lady who planted rhubarb in a hügelkultur bed, but it was a failure because the soil level dropped every year, and she could not cover the crowns of the plants without killing them. She advised only to plant annual plants in a hügelkultur bed because of the expected, and desired, drop in soil level each year. With annuals, you just top off the raised bed before planting. She could not do that with her rhubarb and after a few years the soil level had sunk down so far that she had to dig out everything and restart them in a bed that would drop down in soil level.
I only plant annuals in my hügelkultur raised beds. In fact, I don't have any perennials planted anywhere. So, I really don't have any personal experience with them in hügelkultur beds or in-ground gardens.

Would love to hear if anyone plants perennials in their hügelkultur beds and if they are successful or not.