@Willinator
Will, I'm in zone 9b and we can occasionally dip below freezing and even into the upper to mid 20's every few years. I bought this pop up greenhouse to put up in the winter for those occasions. My FL native tillandsias have survived those occasions, but I've lost hybrids to frost before (tillies don't like wet and cold). As Elaine said the ground and day sun usually keeps it warm enough at night, but I've put a grow light in when many hours below freezing, This would not hold up to snow, but we don't get that here
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This is a good reference chart for cold hardiness on bromeliads.
http://www.fcbs.org/articles/c...
I have two Dyckia plants, they can take the cold down to days in the 20's, so they're very cold hardy, I've never even protected mine.