any known hardy bromeliad?
Most bromleiads are hardy under the right conditions. Are wanting cold hardy ones?
If you mean COLD hardy, the cold hardiest is Spanish Moss (Tillandsia usneoides). Hardy to 8, maybe 7. I have managed to overwinter several large clumps under an island planting of Eastern Hemlocks. Believe it or not, it survived outside but they really seem to hate indoor life over winter! Have not succeeded as an indoor plant.
Im in zone 7b and I only have my bromeliads outside in the summer. I keep them as houseplants, however, this is my first year growing them outside on my porch. I'm going to bring them in when the low is below 65. They hate being chilly.
Tropiflora has a list of bromeliads which will handle the low 20's
Here is a link that might be useful: Cold hardy list
Many Neo's are hardy to 40 degrees with north wind protection..Aechmea are hit and miss...they like sun but no cold for many of them. What genera are you interested in growing?