This Grodan RW108001 Big Mama block is an 8-inch square, specifically designed for large plants and even small trees. It's made from solid stonewool fibers, ensuring that water and nutrients are distributed uniformly throughout the block. This promotes the development of a strong root system during propagation. Since Big Mama does not have pre-drilled holes, it is recommended she be used in conjunction with a well rooted plant from a minimum 3-inch gro-block. Big Mama does require top feeding, so either hand water or use drip irrigation. Sold individually with instructions on the wrapping.