Here’s a quick way to move a plant to a large pot. Put a layer of potting mix in the large pot and set the smaller pot, with the plant still in it, on top. Add potting mix around the smaller pot, tamp gently, and pull out the smaller pot, leaving a well in the potting mix. Carefully lift the plant from its pot, and set the intact root-ball in the well. If the plant was in a plastic pot, you’ll find that the root-ball is a snug fit in its new home. If the plant came from a clay pot, there’ll be a small gap around the root-ball that you can close by tamping, watering, or thumping the pot down on a table.