Grodan Delta 6.5 4″ x 4″ x 2.5″ – Strip of 6



Grodan's Delta 6.5 Gro Blocks Measure 4" x 4" x 2.5" - perfect for transplanting seedlings and cuttings. Once roots reach 1" long these 4" Gro Blocks can be used as a transplant for starter blocks. Grodan A-OK Staters and Macroplugs fit snugly into the pre-formed hole on the top of each 4" Gro Block. Designed to be transplanted into larger Gro-Blocks or Gro-Slabs.

  • Block Size: 4" x 4" x 2.5"
  • Contents: Rockwool mineral fibers
  • Strip of 6 gro-blocks

More Info

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Grodan Delta 6.5 4″ x 4″ x 2.5″ – Strip of 6

Grodan Delta blocks are the most uniform blocks available on the market. They feature improved grooves at the base to promote better drainage. They are available in a large assortment of sizes and configurations to suit all types of plants. These growing blocks are used for direct sowing or “blocking on” of Macro and Multiblock raised plants. AO 36/40 plugs fit well into the hole sizes provided by the blocks. The blocks can then be placed on top of a slab to provide for a larger growing volume. Hugo is the largest of the growing blocks. It provides enough growing volume to support a larger plant, so it does not need to be placed on top of a slab.

How to Use:


  • Saturate the GRODAN Gro-Blocks with pH 5.5-6.5 water when starting cuttings
  • When transplanting, use the same strength nutrient solution to soak the new media as you were feeding the plant
  • If submerging the blocks to saturate, keep them submerged in the solution until bubbling stops


  • Place a rooted cutting, grown in a GRODAN starter into the hole of the GRODAN Gro-Block
  • Do not water for several days until the plant has rooted into the GRODAN Gro-Block but do not allow the block to go completely dry
  • If needed, lightly mist once per day to keep the top of the block moist
  • Do not allow the blocks to sit in standing water


  • If using a drip irrigation system, use one drip stake per GRODAN Gro-Block. Irrigate as needed to keep the block moist but not saturated.
  • If using an ebb and flow system, irrigate when the GRODAN Gro-Block is approximately half its fully saturated weight.
  • If hand watering, keep the block moist but not fully saturated.
  • Do not over-saturate the block after the initial soak as this can slow plant growth.

Transplanting for Larger Plants:

  • For smaller short-term crops, GRODAN Gro-Blocks are all you need. To grow larger plants you can transplant Gro-Blocks onto GRODAN slabs, GRODAN loose media, or soil.
  • Prior to transplanting make sure that the plant is well established with multiple roots appearing on the bottom of the GRODAN Gro-Block
  • When transplanting to a container or outdoor garden make sure the new media is very wet at the time of initial transplant.


Weight 0.6 lbs
Dimensions 23 × 4 × 2.5 in

Product Category

Soil & Grow Mediums


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