Bromus hordeaceus is native to a wide expanse of Europe and the Mediterranean, finding its original habitat in areas that include both the northern and southern temperate zones. Distributed across major continents, lop grass has also been introduced to parts of South America, Asia, and Africa, establishing a presence in various regions. In certain areas such as New Zealand and China, lop grass is sometimes thought to be an invasive species that may have an impact on native ecosystems, although its spread is not everywhere regarded as detrimental.

Lop grass originates from Europe and Asia but has spread globally. It is well-known as a weed because of its robust ability to adapt to a variety of conditions, producing large amounts of seed that can survive in the soil for several years. Its aggressiveness to colonize and outcompete other plants makes it harmful to gardens. Its rapid growth and high seed production allow it to effectively monopolize resources like sunlight, water, and soil nutrients, adversely affecting the growth and development of other plants. The main method of dispersal for lop grass is through its seeds. When mature, the plant shatters, distributing the seeds over a wide area. Also, if these seeds attach themselves to clothing or animal fur, they can be transported to other regions, aiding in its spread.

For the management of lop grass, it's best to act in the late spring to early summer, ideally before the plant has set seed.