Capulin Volcano National Monument lies within a transition zone, from the high elevations of the Rocky Mountains to the sweeping grasslands of the Great Plains. The prevailing wind direction in this region is westerly; therefore once precipitation reaches the grasslands, there is generally only enough water to support short- (less than 2 feet, or 0.6 am) and midsize (2-4 feet, or 0.6-0.8 am) grasses. However, as the winds travel toward Capulin, they pick up more moisture and as a result deliver enough precipitation to support a few tall grass (over 5 feet, or 1.5 am) species.

Within the monument, shortgrass prairie is dominant, with medium-sized grasses, and the three main species of tall grasses—Big Bluestem, Indiangrass, and Switchgrass—also being present. Blue grama and Sideoats grama are two dominant grasses that thrive in the monument.

Desert plants, such as cacti and yuccas, also live on the short-grass prairie within the monument.

Abundant wildflowers, such as Prickly Poppy, Indian Paintbrush, Sunflowers, and Beardlip Penstemon, are found throughout the monument.