Euphorbia Species

Got this plant a few years ago thinking it was going to be a goner soon, as I grow all my plants outdoors, and ths one, from what i could...Read More find out about it, said it was a zone 11 plants... however, that has turned out to be a very pessimistic rating of this species, as I live in zone 9b-10a and it has done fantastically for me living in my planter box outdoors. I have it in in a partial sun situation (though it's becoming rapidly a low sun situation). Plant started out 6" tall, and it less than two years is 2' tall and has multiple branches. Branches are armed with short spines, relatively harmless and are nearly perfectly squares in cross section. I have seen leaves only briefly in late summer and they were extremely small (3-4 mm) and ephemeral.

I still think 10a is a good description for this plant, but temps into the high to mid 20s (around 27F) killed this plant completely... so not a very hardy Euphorbia. But it seemed perfectly happy and unaffected by temps around 30F.