Tropicals & Tender Perennials: How do they do this?, 1 by JBerger

JBerger wrote:
I have been purchasing these for sympathy gifts for several families who have lost loved ones this month. I kept one for myself. I am so excited with this because it is thriving and blooming as if it was in a pot of good soil. I wonder how they get the plant to stay on the lava rock and grow. Anyone know? They also have Neoregelia bromelaids on the lava rock. I am amazed and want to know how they do it. LOL