I don't have the answer to your question but just for your information, there is a Palm & Cycads Forum with some real experts on these kinds of trees there. :-)

Low single digits or 0 F is pretty sure to kill it.

Agree,

Short duration might be okay but a few/several days of reoccurring temps that cold wouldn't be good.

What I have seen in my area has given the impression that these tend to start burning under our conditions above 0F - maybe something like 10F.

Dave you probably told me this when I visited your garden but if so I forgot, were the ones you grow somehow specially selected for hardiness or just random ones you bought down south somewhere? TBH though, a lot of the supposed 'hardier' ones over the years have seemingly just proven to be gimmicks. And not really proven much hardier. Like 'takil'.

The more interesting palm in Dallas is the huge Jubaea imported from California years ago. Hope they give it a chance to recover. This is the thing about winter damaged plants. My relatives in VA Beach have humorously observed how when Oleanders are killed back every 10 to 20 years, people stupidly pull them out...when they would recover if just left there...and then end up replanting them a couple years later anyhow. Granted they live in the wealthiest area called the "gold coast" aka North End so people probably pay landscaping companies big money just to make sure everything looks alive all summer. One actually sees way more borderline subtropicals planted in the somewhat more blue collar area called Sandbridge.

As for the Jub it's probably dead but that species has recovered from somewhat similar cold including almost 0F in IIRC, Montpellier, FR. (mitigating factor is winters in southern France are actually a steadier cold that probably helped induce as close to a state of dormancy as possible...Dallas was over 70F a couple weeks ago!) Not a chance it could take anywhere near that cold every winter though. Or even prolonged through a single winter! Later this month will probably be back in the 60s in Dallas. Likewise the Phoenix I saw in El Paso, 2011, burnt to a crisp by almost 0F in 2011, recovered. Because average winter highs there are over 60F with very intense sunlight and dry conditions. They would never have that chance to recover from a cold winter in a place like VA Beach which is why there are no trunked Phoenix there!

davidrt28 (zone 7), I'm sure I started these Trachys from seed, but TBH, I can't recall where I got the seed. Could have been a few places. There is nothing special about the provenance of these Trachys to my knowledge.

Windmill Palm was the only one that made it after a three day freeze back in the mid 80s. The frowns may die back but the palm will begin to show new growth when the Mexican palms all died.

Texas is a big place so I assume you just mean in Dallas! Along the lines of the hardiest feather palms like P. dactylifera and J. chilensis, there are reports of some strains of truly pure W. filifera (not hybridized at all with W. robusta, which is apparently somewhat unusual) surviving around 0F in dry climates, like parts of New Mexico. Most big 'skydusters' throughout Texas though ('Mexican palms' I think you are referring to) are less hardy because W. robusta grows much faster.

When I drove through El Paso just after the 2011 freeze, I myself saw scores of dead looking skydusters. However according to posts from locals at the time, some, with mostly W. filifera genes presumably, did survive.

Well, memetexas, maybe they needed to cover their frowns with their palms....

cute

You might try Dwarf Palmettos (Sabal Minor)..they are Oklahoma's only native palm tree. Very very cold resistant