The pots can become really hot during summer. The temperature of the pot can easily go over 100 degree F while air temperature is just above 80 degree. The nursery pots are typically black. They absorbed radiation heat from the sun. This can push the temperature even higher. Sometimes, it can get so high that kills the roots. This is particularly true for smaller pots which can increase the temperature quickly under the hot sun.
By simply painting the pot what can drastically reduce the temperature of the pot. Spray paint is very easy to apply and dry out quickly.
Painting pots