Kuso or Okuso is waste or garbage. In this case, it refers to the waste created in the production of hemp yarn: this kimono was woven from the detritus and crude materials left over from hemp yarn making. This waste, or okuso, was spun into yarn and woven by rural people to make their garments. Most likely the better quality yarn they created from hemp plants was sold to those that could afford it, probably urbanites.
Sri is a textile gallery in Brooklyn, New York, USA, specializing in antique Japanese folk textiles, highlighting the indigo-dyed cotton utilitarian fabrics and boro--or patched and mended--textiles of old Japan.