Grodan Stonewool Gro-Block Hugo - W/ Hole - 6" x 6" x 6" - Growers can start cuttings and even grow plants to maturity in this large Grodan Gro-Block or transfer it to a larger stonewool slab once roots have been established. Gro-Blocks can be planted directly into containers for soil gardening as well. This is a single 6" x 6" x 6" Gro-Block with a pre-formed hole. Grodan stonewool is known for its quality, consistency and performance. Holes are perfect size for any 1.5 starter plug.