I went out to the garden before the rain started and removed some of the soil from crowns of the ditch lily, Hemerocallis fulva
'Europa'. I chose it because I have a clump naturalized on the edge of the grassy area that has been untouched for many years and it was started as a single fan. Europa has been shown to be able to reposition its crowns. I would assume that its crowns are naturally at good positions in the soil. I then took some photos.
Crown depth of Europa
There are four crowns in the photo. I measured the depth of the three in the cluster. The soil level is higher on the left side of the photo, lower in the centre and then higher again on the right side of the photo.
Measured from the soil level on the left and since it is about the same on the right, I assume the natural soil level -
the deepest crown is 2 1/8 inches deep, the next crown is 1 5/8 inches deep and the third crown is 1 1/2 inch deep.
Measured from the soil level in the centre -
the deepest crown is 1 5/8 inches deep, the next crown is 1 1/8 inches deep and the third crown is 1 inch deep.