Clean all the dirt away from the crack or broken area on the pot. Leave the pot to dry completely after cleaning.
Apply silicone caulk into the crack or damaged area. If you have broken pieces, apply caulk along the edges of the shard.
Press the cracked or broken area together so the caulk bonds, and bind the pot with string to hold it in shape.
Leave the pot to dry upside down for several hours or overnight. If your caulk recommends waiting longer, then do so.
Remove the string from around the pot once the caulk has dried completely.
Scrape away any caulk that leaked onto the inside or outside of the pot with a scraper.