Some grasses grow so fast in spring that you can actually hear them growing.

The phenomenon of hearing grass grow is most commonly associated with Big Bluestem (Andropogon gerardii), a dominant species of the North American tallgrass prairie. During peak growing season in May and June, these plants undergo rapid cellular elongation fueled by heavy spring rains and rising temperatures. Growth rates can reach nearly 3 centimeters per day, which is exceptionally fast for non-woody vegetation.The sounds heard by observers are caused by physical expansion of the plant's vascular bundles and friction between leaf sheaths. As the stem, or culm, pushes upward, rigid cellulose fibers rub against one another. This creates microscopic snaps and cracks that, when multiplied across thousands of stems in a quiet field, become audible to the human ear as a faint rustling or popping sound.Early 19th-century pioneers traveling through the Great Plains documented these sounds in their journals, describing the prairie as a living, breathing entity. Modern botanical studies confirm that Big Bluestem can reach heights of 2.4 to 3 meters, with roots extending up to 3.7 meters underground. This massive biomass production requires incredible amounts of energy and rapid structural development, making the physical stretching of the plant literally noisy.Researchers at institutions like Kansas State University, which manages the Konza Prairie Biological Station, study these growth patterns to understand prairie resilience. They have noted that rapid growth is an evolutionary adaptation to outcompete other plants for sunlight. The audible growth serves as a testament to the sheer biological force of the tallgrass ecosystem, which once covered over 170 million acres of North America.