I grew the pink/white mixed cosmos back in NM (z7) and they got about 4-5 ft tall. I was about 15 and had a huge bed of cheap seeds--cosmos, bachelor buttons and pinks/dianthus. I remember Dad getting pissed off next spring and summer when volunteer cosmos plants all over his yard randomly sprouted--he was mowing every weekend to take them down to lawn height:lol: I'm super lucky he didn't make me go pluck em out of the lawn!
The foliage on those were denser than the sulphureus that I grew later. I decided to start a new container of an orange type, seeds were some I had collected 4 yrs earlier, it was mid July and I did get 4 ft tall plants with huge blooms right up till late October. I do generally prefer the sulphureus colors and foliage.
