Q.Dead and frozen yucca
I bought a yucca houseplant and accidentally left it in my car while I was running errands. It was very cold outside, well below freezing and it was in the car for about 5 hours. The leaves are brown and dropping and I haven’t noticed any recovery. I’ve tried watering it. Any other suggestions or have I killed it for good?
Plants that have been frozen often lose all or most of their leaves, but they still have a good chance to recover. The best option is to leave the plant alone and see if it perks up over the next few weeks or even months. Don't give it any more water or fertilizer until it shows signs of recovery or until the soil feels very dry to the touch. Damaged plants will often slow down their water and nutrient usage to almost nothing.
If the leaves turn completely brown or dry, you can cut them off. Eventually, the plant should produce new leaves if it's alive. If it doesn't, try cutting back the trunk to a part that is visibly living and let it regrow from there.