We have some tall ceramic pots on our deck that have smaller than normal openings. Every year I buy the pots from Costco and squeeze them into the ceramic pots for an instant container garden. This year, however, the pots from Costco are not flexible and sit WAY higher than is acceptable. I found some plastic pots that fit into the ceramic pots. I would now like to transplant the plants that I bought at Costco into these pots. How can I easily and safely do this without ruining the plants? The pots are about 13" diameter and hold several different plants. Thanks for your help.