Tillandsias are the most widespread of all of the bromeliads--they can be found everywhere from rain forests to beaches. There are over 500 known species of this plant, and more are still being discovered. Tillandsia enjoys popularity as a novelty plant because of its ability to grow on nearly any surface without the aid of soil. Tillandsia reproduces most reliably by the production of offshoots (pups) that can be split from the mother plant and re-"planted."
Wait until the tillandsia pups reach at least 1 inch in size. But keep in mind that larger rosettes are easier to separate. The best time to split tillandsia pups is when they reach roughly one-third to one-half the size of their mothers.
Use a sharp pair of pruning shears to cut the pup from the mother plant. Then use your fingers to carefully pull its roots away from whatever substrate medium they have attached themselves to.
Use a few drops of glue (any type but silicone glue) to affix the tillandsia pup to its new substrate growing medium (you can also tie the plant onto the growing medium if you prefer not to use glue). This will keep it attached until its roots take over.
Mist the pup and the mother with water from a spray bottle.