Comment Re:So does this qualify as 'organic'? (Score 2) 279
Yup. The growing medium just needs to be structurally supportive, non reacting, and in some hydroponic setups, capable of holding a little bit of water.
The only personal experience I have is with an aerogarden unit, and the seed pods for that are just plastic sponges. Though I have read about using ceramic beads, coconut fiber, or even just clean gravel if you're cheap.