How does Tithonia rotundifolia grow in San Diego? How big does it get? Is it annual where it doesn't freeze? Does it reseed? I do know that gophers like it!
It was an annual for me. It got tall- over four feet as I recall. It did not reseed, but that's because I deadhead. I imagine you could collect seed, though. I love the color.
I grew it in Mission Viejo. It would get 6-8' tall over a trellis; I would prune it back hard late in the year. It did freeze during the odd cold snaps, but came back and recovered quickly. At least in the more temperate regions of SoCal. It does reseed. I asked my hubby to not harm them because I wanted to transplant one or two when we moved; he forgot and gave them all a drench of Round-up. sigh I only had the plant 1 1/2-2 years and found 5-6 seedlings. A more mature plant may produce more seedlings. Mine was located in an area where there was little opportunity for seed to get going; in a different location, the seedlings may be more numerous.