Baby the roots.
The delicate tips of a plants roots are the primary place where it takes up water and nutrients. Be careful not to damage the tips by cutting or tearing the root mass when planting. If you damage them, the plant will take longer to get established and start blooming until new ones can form. One exception: If you lift a perennial plant from a pot and see that the primary roots are wrapping around themselves in the pot, you should carefully straighten the circling roots and cut them so that they will grow into the surrounding soil.