Why Air Plants Don't Need Soil

Like all plants, air plants have leaves, roots, and bloom but don't need soil to grow. Why? That's because air plants, aka Tillandsia, come from the family of epiphytes and this means, instead of growing from the soil, they anchor themselves to other plants without being parasitic or causing harm. You're likely to find them on tree trunks in tropical rainforests as the tree’s canopy shades them from the sun, giving them filtered sunlight exposure.

An air plant's roots are meant for anchorage to another plant and not for absorbing nutrients or water like soil-needy plants. So, how do they survive? Well, these plants have trichomes (tiny scales) on their leaves for nutrients and water absorption.

In a tropical rainforest that’s densely populated, there’s usually a harsh competition for light, air, nutrients, and water. To exclude themselves from this competition, epiphytes have evolved over the years and now have their root systems in the air causing them to adapt perfectly and live in a harsh environment.

This is why air plants don't need soil to survive since they are epiphytes. Living on trees have granted them a higher place in the forest canopy. They’re able to get enough filtered sunlight in the tree's canopy without any need to compete with other trees and vines in the wild than they would have if they were to be living in the soil.  

Now you ask, "If they don't need the roots, what do I do with them?" Well, without cutting the roots too close to the plants (to avoid damage), you could simply anchor or mount them onto any surface that you like for display. Something like a wreath or hanging planter isn’t a bad idea. They will have a pretty firm anchor over time and moderately strong wind can’t remove them.
Being a not soil-needy plant, an air plant would do just great being displayed anywhere. Yes, you're allowed to get creative or even send them as a gift to loved ones. As long as these plants get the needed filtered sunlight and good air circulation, you're good to go.