"Good growing season color" is one of the categories that can be checked in the Foliage subsection of the plant data form.
I have always reserved this for foliage that's red, chartreuse, etc. -- anything but plain green. I'm seeing people add this to plants with standard green foliage, however. If it applies in this case, how meaningful is the description? Wouldn't this mean that every plant displays "good growing season color"? After all, there are no plants with colorless foliage.