I have no experience with clay pots, or terra-cotta, if that is different.
Cracked plastic pots, I tape with Gorilla Tape. That makes them stronger than brittle plastic!
When I have two cracked or brittle plastic pots of the same size, after taping the cracks, I nest them together with the cracks 180 degrees apart. Then I use them as ONE pot with two brittle layers, stronger than either pot would have been without the crack.
Maybe, if there is a little airspace between them, that even keeps roots slightly cooler. For me, that is seldom an issue. A "hot" day would be one that goes over 80.
