I have heard that here in the south to plant the crown right at ground level or actually above. I just plant and try and make sure it's not more than an inch below the surface. I have never lost any during the summer to crown rot just in the winter when we had the hot/cold/hot/freeze weather.
At my old place I had daylilies in the ground and I mulched these to keep the soil moist but since all the beds now are nothing but pine bark there is no need to mulch.
