3 inch / 7.5cm Grodan Rockwool Blocks are used to transplant your rooted cuttings or seeds into with the idea being to grow your babies to a suitable size before moving them to your final pots or hydroponic system.
These Rockwool blocks are available with a 2.5cm (small) or 3.6cm (large) hole.
Before using a Rockwool growing medium, always pre-soak it for 24hrs in a weak nutrient solution (less than 1 EC) with a pH of 5.5 - add in a small amount of root stim to increase your EC. This presoaking will negate the naturally high pH in the Rockwool.
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