Zinnia
Zinnias, a long-time favorite, have undergone a serious make-over these last several years. The old standbys are still available, but the excitement is in the shorter, broader, more mildew resistant varieties.
Can be planted in pots, but do best in the ground
VERY heat tolerant
Do NOT require a lot of water or fertilizer
Deadheading not necessary, but helpful if under long, periods of stress conditions
Flowers can be single (daisy-like) or double, solid or bi-color
Colors are mainly in the reddish/yellow/orange spectrum, with a few pinks
Newest varieties typically have a more spreading growth habit
Heights can vary from several feet, to the most common 12” +/- in new varieties