Production of plants in containers offer many advantages over field production. Shorter production cycles, larger numbers of plants per acre, and the ability to continuously market and ship plants are among those advantages. However, there are some disadvantages including more intense cultural practices, a relatively short window of optimum marketability due to container size restrictions, and rapid daily temperature fluctuations within the container substrate (growing medium). This publication will provide information about plant response to high root-zone temperatures, identify critical temperatures, describe the factors that influence temperature fluctuations, and suggest cultural practices to reduce heat stress in container-grown plants.