We get frost here in Florida zone 9a/9b but frosts are usually few and far between. My
Pygmy Date Palm (Phoenix roebelenii) has been hit by frost a time or two and one winter a few years back we even had a very hard freeze with a lot of ice (which is rare) and the P. roebelenii was fine with a blanket thrown over it. I'm doubtful they would be able to withstand continuous temp's below @ 50ยบ unless grown in a container and moved indoors during winter.
