Roll a terracotta pot onto to some leftover felt and cut out a rainbow-shaped piece that will cover it. Pin that piece tight around the pot.
Sew or staple along that line and remove your pins. If you sew, I recommend not lazily assuming you can just use the sewing machine on the floor. It is a bad idea. Add a double row of reinforcement, cut off the extra on the seam. Leave about 1 cm on the bottom and the side-seam and 3 cm on the top. Deglove the pot, roll the sleeve inside out and reinsert your pot.
Purse-string sew the bottom, but let me save you the shivers and tell you that needle nose pliers and extra suture is a bad idea because needle + terracotta = worse than nails on a blackboard. Tuck the top into the pot, fill with dirt, plant away.
UPDATE: A beloved pet knocked over this plant after seeing a squirrel and it shattered the terracotta pot inside the felt. The felt kept the mold of the pot, with the exception of a thumbprint from where I lifted it to seat it in its new home: a bowl. Sounds like it’s time to re-pot it again.