Because plants at garden centers and nurseries often are root-bound, and because the soil mixes the plants come in sometimes are not ideal, you'll often need to repot or pot up new plants immediately after purchase. Many plants also require regular potting up throughout their lifetimes. Taking a plant out of a pot and putting it back in the same or same-size pot is called repotting. Taking a plant out of a pot and putting it into a larger pot is called potting up or potting on. Plants regularly need potting up to keep their roots from compacting, a condition that harms most houseplants (although a few tolerate it well). Signs of compacted root growth include slow growth, quick wilting after flowering, yellow lower leaves, small new leaves, and roots growing through the drain hole. Check the roots of fast-growing plants frequently to see if they are compacted. Slow-growing plants usually need potting up no more than once a year, or even less often.
1. When potting up, choose a pot one size larger than the pot the plant is in now. Make sure the pot is clean. Place a shard from a broken pot or a piece of screen over the drainage hole to keep soil from washing out.
2. Wet the soil the day before removing a plant. To remove, hold your hand against the soil and around the stem, turn the pot upside down, and tap the rim on a surface. Once it's loose, grasp the plant near the soil; pull gently.
3. Keep the root ball as intact as possible, unless the roots have become a snarl. If the roots are tangled, lightly loosen the outer part of the root ball with your hands or a knife, being careful not to damage the delicate roots.
4. Place some soil in the new pot, then position the plant on top. Adjust plant to leave enough space below the rim for easy watering. Fill with soil around the root ball, burying plant to same level. Tap pot; add soil as needed. Water.