The Grodan Delta Rockwool Block offers a great option for sowing or "blocking on" of macro and multi-block raised plants. Give your favorite plants all the protection, warmth and nourishment they need with our amazing collection of live plant accessories. Designed to increase growth, these products are sure to make your favorite plants bigger and healthier. Constructed for high quality materials, this range is sure to offer you lasting functionality. Product Features: Features grooves at the base to promote better drainage. It is used for direct sowing. The plugs fit well into the hole sizes provided by the blocks.