I was wondering the same thing. I grew tulips in my zone 9 California garden. Is the deciding factor the number of chill days? The same numbered zones can have dramatically different climates. The low temperatures might last only a couple of weeks in one location and a few months in another.
"Most tulips need at least 12-14 weeks of "cold period" to develop a beautiful flower. This makes it hard to grow tulips in warm/tropical climates, but not impossible. The cold period is normally given by nature when the soil temperature drops below 55 degrees."
From How to Grow Tulips in Warm Climates
https://wickedtulips.com/pages....
