Blackgrass or black-grass or black grass may refer to:
Plants Black-grass, British common name for Alopecurus myosuroides, a damaging weed in wheat crops Black-grass rush or blackgrass, American common name for Juncus gerardii, a salt marsh plant used for facing dykes Black mondo grass, a cultivar of Ophiopogon planiscapus
Other uses Blackgrass (album), an album by Earl Lee Grace