In this tutorial, we learn how to root prune container plants with Lee Reich. First, remove the plant from the pot then take a knife and slice the root ball back. Don't worry about hurting the plant while you're doing this. Trim the roots around the plant until they have become small enough to fit into the pot again. You can also use pruning sheers to cut back loose roots that are too long. Now, place the plant back into the plant and fill it up with brand new soil around the edges. Keep watering your plant and do this as often as you need, around once a year.