1. If the plant is in bloom, cut off the flowers, trimming the stems back to just above a set of leaves. This will make the plant direct its energy into taking root in its new container or the garden soil.
2. When planting annuals, always loosen the roots before setting them into the planting hole. If the plant is not root bound, you can simply loosen up the roots using your hand. If the plant is root bound (roots a tangled mass in the shape of the pot they were growing in), go ahead and cut off any thick jumble of roots at the bottom, and then use a sharp knife or scissors to make several vertical cuts around the edge of the rootball. Then use your fingers to reach into the rootball from the bottom and loosen up its shape. The clean cuts you made will stimulate new root growth when the plant is in its new home.