Zinnias are the perfect annual for a bright pop of color mid-summer to fall. They like lots of sun, are drought tolerant, and range in height from about 6 to 14 inches tall. The taller varieties are well-suited for cutting for vase arrangements. Some varieties are prone to powdery mildew, but this is usually just an aesthetic problem and can be avoided by letting the soil dry out between watering and avoiding getting the foliage wet when possible.