Delta Gro-Blocks are cubes of stonewool (rockwool) that have a grooved base which promotes drainage to avoid root rot. Grodan stonewool is pH neutral, making it easy to maintain the ideal gardening pH value of 5.5 - 6.5. Each block is wrapped in white plastic on all sides for individual use. 

They can be used for direct planting or "potting up" of plants started with Grodan Macroplugs or A-OK plugs. When your seedlings have a couple of small leaves and the roots emerge from your Macroplugs or A-OK plugs, soak the the Gro-Block in pH5.5 water overnight and insert the starter plugs in the holes the next day. Hold off watering for 1 to 2 days to prompt the roots to expand quickly into the Delta Gro-Block.

Once your plants have outgrown the Gro-Blocks, simply expand the growing medium by blocking onto a Grodan Slab. No pots, no soil, no mess!

Not using hydroponics? Stonewool can be planted directly into soil, indoors or out.

Delta Gro-Blocks provide more evenly distributed pores and a robust design, giving your plants the optimum zone for root growth throughout the entire block. Stonewool is recognized the world over as the ideal hydroponics growing substrate.

Dimensions:

3" x 3" x 2.5" - strip of 8 - choose pre-formed holes or NO holes
3" x 3" x 4" - strip of 8 with pre-formed holes
4" x 4" x 2.5" - strip of 6 with pre-formed holes
4" x 4" x 4" - strip of 6 with pre-formed holes
HUGO 6" x 6" x 6" - a single block with pre-formed hole

More info (PDF format)