according to the link below they can withstand 20F in CA.
see posts at the bottom of the page.
you need to post pictures. full tree, close-up of leaves, flowers/berries if any.
it's nearly impossible to ID anything from just a description.

Here is a link that might be useful: CA tupidantus posts

Here is my neighbor's big tree that resembles my Tupidanthus that I have purchased in the past. They said the landscaper installed this when they originally landscaped the property, which means it was planted almost 40 years ago. They recall that it was fairly good sized when planted. The largest trunks are now 6" in diameter. I'm assuming this IS a Tupidanthus. It clealy survived the 1990 freeze that took out both of my tupidanthus in my former house, which is in the same climate a few blocks West. I planted more in my current house, which is 100 yards from this house, and they froze and died in a much more minor freeze about 7 years ago.

This is the one I'm trying to duplicate that seems like it might be a tupidanthus but it seems different some how. The house is only 31 years old so it seems like it would have to be a different variety. That trunk is about the same size as the 16" square cement blocks for the fence post right next to it.

Can this be the same variety.

i looked around .. people post that they have them in SF!
" it thrives in ur-zone 17 San
Francisco, whether in the dankest fog belt of the
Sunset District or in the sunny Mission District. It
has very powerful roots and grows very fast. Seems to
defoliate below 28F, but bounces back with redoubled
efforts."
and also this:
" ..in Long Beach, Ca for 13 years and had a Tupidanthus in my front yard, very close to the house. the winter temps could get down as low as 28 degrees sometimes. I never had any troubles because of the chill."

may be you got sold S. actinophylla by mistake? it's rated to z10 only. it looks very similar except for flowers. do you know if your flowers were the same as your neighbors?
pictures?
people on hort.net suggested vitex lucens(puriri) as an alternative. it's a NZealand evergreen with very pretty flowers. i am not familiar with it, but you can also ask in cali forum.

Here is a link that might be useful: puriri

Petrushka,

I got so busy trying to figure out how to post more than one picture in a post, I forgot to thank you for the links to Dave's Garden that were very helpful.

Thank you for the help, it was very informative.

I can easily believe problems at 28 degrees since it hits that fairly regularly in Upland - at least every couple years. In the freeze down to mid 20s around 7-8 years ago, mine was taken out completely and the neighbors tree shown in the first picture survived. Mine is in an almost identical location against the south side of a similar house just 100 yards west.

I was amazed at the info from the person in Long Beach. I lived just a couple miles down the coast in Huntington Harbor for a long time before moving back "home" to Upland. The original Tupidanthus plants that I planted were patio plants at my house in Huntington Beach. It froze ONCE during the 18 years I lived there and I think 28 degrees was the all-time record low that broke the record that had stood for around 100 years.

o-ops! do not mention DG site - its' verboten! you can't post a link to it directly - won't post! but tiny works ;).
posting in cali regional forum should be able to get you more local info.
did you search Florida forum? they might have similar to yours conditions in central/no fl.
i just surf a lot. i am a plant-info-junkie.
you can only post 1 pic at a time here (very outdated, i know). otherwise you need to set up an ac with some photo-storing site like flicker and then you just post links to it.
apparently the pic of the flowers will tell exactly what you and your neighbors got. so try to get that and post then.