Q.What Can I Do To Assist Cast Iron Plants Which Appear To Have Frozen ?
Several cast iron plants were planted in the shade of oak trees last October. We subsequently experienced a low temperature of -8 in an atypical winter storm here in North Central Texas. The once-green leaves are now totally tan, though some of the stems are still green. What should I do now: trim back to the green stems, replace the whole plants, leave the plants alone and see what happens?

Certified GKH Gardening Expert
They should be hardy to zone 7, which is to 0 degrees F, so doesn't bode well for -8 temps. However, since you see green, I would wait it out and see if they return from their roots. If you see new growth coming up, you can trim off the old growth.
https://www.gardeningknowhow.com/houseplants/cast-iron-plant/outdoor-cast-iron-planting.htm