In general, you can follow the same basic techniques for repotting a plant as you do for regular planting. Your biggest challenge may be getting the plant out of its current container. This may be easy, or it may take some effort if the root ball is a tangled mess. For small to medium plants, turn the container upside down, tap the rim, and slide the plant out. For larger, heavier plants, tip the container on its side and roll it around gently. You may need to use a rubber mallet to tap the sides if the root mass is stubborn.
Protect large ceramic and clay pots from chipping or cracking by wrapping an old towel or piece of carpeting around the outside before you tilt them and tap the sides.
Try to slip the container off the plant, rather than yank on the plant to pull it from the pot. In some cases, you may have to trim off large roots poking through the drain hole to release the plant from its pot.
With large containers, let the roots dry out a bit first because this tends to shrink them, making them easier to extract from the pot.
Next, examine the roots. For plants going into larger containers, gently loosen and pull apart tangled or circling roots. If you’re repotting into the same-sized pot to slow growth or to maintain the plant’s current size, you’ll want to root prune it.
Add an inch-deep layer of fresh, moist soil mix to the new container. Place the root ball in the new container, adjusting the depth of the fresh soil as necessary so that the top of the root ball sits a few inches below the rim of the pot. Begin filling in the gaps around the edges with fresh soil mix, tamping it down gently as you go.
If you don’t have time for a complete repotting job, a temporary solution is to remove the top few inches of potting soil and replace it with fresh potting mix with a little added fertilizer.