Fifty-six field plantings of `Baccus', `Citation', `Packman', and `Southern Comet' broccoli were made in Charleston, S.C., at 2-week intervals from February to November from 1990 to 1992. The objective was to determine broccoli's response to growing season mean (GSM) temperatures for several important market quality characteristics, such as head shape, color, density, leafiness, and bead size. Regression analysis determined whether quality was more affected by GSM minimum (min) or maximum (max) temperature for each head quality characteristic. Head leafiness and density of `Baccus' were insensitive to GSM min (7.0 to 23.5 °C) and GSM max (17.5 to 32.5 °C) temperatures experienced during these years. `Baccus' head color was unacceptable at 20.5 and >20.2 °C GSM max, respectively. Head density of `Citation' was unacceptable at 28.9 °C GSM max and head shape was unacceptable at 25.7 °C GSM max. Quality of `Packman' was unacceptable for head color at 27.3 °C GSM max, head leafiness at >32.0 °C GSM max, head density at 18.0 °C GSM min, and head shape at >22.0 °C GSM max. `Southern Comet' head quality was unacceptable for head color at 16.5 °C GSM min, head leafiness at >32.0 °C GSM max, head density at 16.2 °C GSM min, and head shape at 25.3 °C GSM max. GSM min or max temperatures did not affect bead size of any cultivar during any planting time studied.