Here are some photos of frost damage, (and no damage,) following 6 days and nights of below 10F. The sustained cold with a slight breeze in very dry ground was different than previous cold years. We only got above freezing for about 4 hours every day for about 10 days and were below 20F from about 6 pm to 9 am.
Several of the perennials that are under the cover of trees felt pretty badly about the cold.
Many of the leaves froze on the bushes and trees.
The Buckbrush from the inner coast ranges is doing fine under the drought and cold.
We commonly see plants like Silver Lupine, Lupinus albifrons, that grows to 8000 ft(2400 meters) freeze here.
Salvia Pozo Blue made it in flying colors. It can't seem to make it at Big Bear City or Potland Oregon but should do fine in most of California.
Coastal forms of Coffeeberry seem to be good to about 5F. Here is Tranquil Coffeeberry.
Pickeringia montana, Chaparral Pea doing very well after the drought and frost. AND the deer haven't bothered it.
A Fremontia Pacific Sunset next to a Ceanothus tomentosus after the frost. The Ceanothus is fried, the Fremontia is fine.
The Santa Cruz Buckwheat did fine in the ground, the pots got beat up though.
The Ribes viburnifolium burnt in the pots and a little in the ground, but it looks to survive.
Ribes speciosum is amazing, coming back from summer dormancy like nothing is happening.
The front of the main building gets very cold, and hot. This Ceanothus Remote Blue has been there for about 15 years and done fine until this year.