What does "crock it"mean?

I'm reading a book on houseplants and I quote" choose a small claypot and crock it". Then it says to add soil. I've never heard this used as a verb before and I'm mad at this author for expecting us to know what it means , it seems archaic. The dictionaries say it means a clay pot or as a verb release color when rubbed, of badly dyed fabric, or to set up on a low stool.