How to Prune rush-like air plant?
Remove individual rosettes that have died after flowering

rush-like air plant · Tillandsia juncea
Plants need no compost; they are glued or wired to a support. Grow under glass in bright but diffused light with good ventilation. From spring to autumn immerse in rainwater twice a week (more in hot, dry conditions), drain well and allow to dry. Can stand outside in summer to benefit from rain, additional light and humidity. See Air plants for more
Remove individual rosettes that have died after flowering