I don't trim the roots when I plant, unless they are damaged or broken. I dig a hole deep enough to accommodate the roots, then I add my amended soil, and build a little cone and sit the crown on the top of the cone with the long roots draped down over the cone, then I gently add soil all around the roots and make sure there aren't any gaps under the crown. I add soil until the crown is covered, but not deeper than 1 inch. Then a thorough watering, and I am done.
Others may have more suggestions, but this is what has worked for me!
