Roots packed firmly in a pot don't take up supplements efficiently. Loosen the plant's roots carefully with your hands immediately after removing them from the old pot, enhancing good nutrient absorption. Thinning long roots can be removed but leave the thicker roots at the bottom of the foliage. If the plant is root-bound – the roots are developing in very tight circles around the base of the plant – lose the plant's roots as best you can and give them a trim using a sharp knife.