Larger pots are quite expensive, so it pays to repair cracks.
Start by thoroughly cleaning and drying the pot. Squeeze a small amount of waterproof silicone caulk into the crack. Remove the wire after the silicone has dried, and scrape away any excess adhesive. Inspect terra-cotta pots carefully for flaws and cracks before buying them. Hold the pot upside down by hooking a finger through the drainage hole.