Wintering plants in zone 10b, Los Angeles
I have about 45 cacti and succulents growing on top of my garage in west Los Angeles, zone 10b. Full sun all day. I keep the sensitive ones under a 30% shade cloth. Los Angeles rarely gets frost and the occasional night in December or January that we do it only last for a few hours. Average low temperature in December is 48F (9C). We get pretty much all of our precipitation during winter. I will protect my plants by covering them with tarps during the two or three storms that we get. I dread having to bring them inside, but if a lot of rain and cold is expected I might bring them down and inside the garage.
Reading about each plant is confusing: "Prefers 60F, can tolerate freezing for short periods of time", or "Minimum Avg. Temperature: 60F, tolerates frost".
So what winter preparations would you do in my situation? Is the winter weather where I live harmful to some plants?
(Some plants of mine that might be cold sensitive: euphorbia ambovombensis, adenium obesum, adenium arabicum, adenia glauca, euphorbia decaryi, abromeitiella brevifolia)