It was below 20F for --- hours. Will my Palm Trees Survive?

I'm worried. Windmill palms usually won't show any damage as long as temperatures stay above 10F, but it's not just the overnight low that's a factor ... duration of cold plays a HUGE part in a plant's survival and there really isn't enough data on it. 

So that's where I come in! I want to show you not just how cold my plants got, but how LONG it stayed cold.

The Cold Snap

Temperatures dropped below freezing by midnight on Saturday, December 21 and stayed below freezing until Tuesday December 24th. Here's the high and low temperatures for these dates

(high/low) **temperatures are in Fahrenheit 

Dec 20: 37°/32°

Dec 21: 32°/20°

Dec 22: 20°/13°

Dec 23: 26°/12°

Dec 24: 36°/26°

Dec 25: 35°/27°

Temperatures dropped below 20F for 36 hours! It started just before 12AM on Dec 22 and remained below freezing all day. We jumped above freezing at noon on December 23. 

WHAT WAS PROTECTED?

- Sabal Uresana 

    Christmas lights and flipped a planter over to keep the heat in

- Cordyline australis 

    Christmas lights and a frost cloth tent. Very limited protection

- Large Windmill palms at my parents   

    Christmas lights & frost cloths. 

- Hardy Gardenia Summer Snow and Crown Jewel at my parents 

    Christmas lights & frost cloths 

WHAT WAS UNPROTECTED?

- Fatsia Japonica (including one that is containerized!)

- Gardenia "Frost proof" and Chuck Hayes (First year for the chuck hayes)

- Madison Star Jasmine 

- All 3 Windmill palms in my yard 

- My 2 Sabal minors 

- My Needle Palm

- My Farfugium japonica 

- Ruby Cactus (in a container) 

- Yucca gloriosa & silver anniversary (and of course the recurvifolia)

- Evergreen Dogwood (never gets covered)