The answer to how long it takes roots to form depends on the warmth of the soil, fertility and even the variety of bromeliad. I have had the pups or young side shoots root in warm soil on a bright windowsill in 3 to 4 weeks. Professional growers may be able to see new roots sooner by supplying bottom heat to the pots or flats and by using a rooting hormone on the cuttings. Be sure the new cutting is kept in a moist but not wet soil medium and be patient. I do know how hard it is not to pull up the cutting and check for roots. Keep growing, Marianne Binetti