How Cold Does It Get In Zone 9 -- Really?
If you've just moved to zone 9 in Florida, or even just relocated within zone 9, one of your first questions is "how cold does it get here?". And the answers are so conflicting you wonder if anybody here knows what a meteorologist is!
Here's why there is so much variance:
Zone 9 catches the leading edge of the cold fronts as they move into Florida and where they stop is going to vary tremendously based on how the wind is blowing elsewise or not when they arrive. Just a few miles from where the cold front comes to a screaching halt can be as much as 7-10 degrees warmer.
Additionally, the cold fronts usually do not come in in a straight line: they push downward in an awkward "thumb print" that frequently finds the low spots along the northwestern edge of the front, creating a colder pattern from Crystal River to Bell and pushing downward almost into Masaryktown south of Brooksville. But high spots nearby, even very near to the northeast of Brooksville can remain much warmer.
That's how they lost the citrus in Masaryktown in the famous freezes of the early 20th Century --- yet the high points of Spring Lake (Blvd) were unscathed just 4 miles away.
And sometimes that "thumb print" of cold will make its way over Ocala, causing similar discrepencies from neighbor to neighbor. But rarely does that "thumb print" occur on the east coast of the state, leaving parts of Jacksonville (next to the Intercoastal) to Daytona Beach with the warmest weather of the same latitudes that are freezing on the west coast.
So just how cold is it going to get where I live?
North & North Central Florida are famous for quick temperature changes. 80° one day, and 25° or so two nights later. Gainesville can see temperatures as low as 18°, but it only lasts a few nights, maybe happens 2-3 times in a given winter, and 3 days later it's a balmy 72°!
And the coldest winters generally run in 40 to 50 year cycles. In the meantime, it feels like warming trends then bam! you're hit with another Artic winter.
So that is why we don't grow tropicals outdoors this far north. We have to be prepared to either pull them into a "Florida room" for a few days, or construct an instant mini-greenhouse over them for a short duration.
If you live south of Ocala, or have a warm micro-climate on the southeast side of a house, you might venture into a tropical here and there -- some are tolerant of short, light freezes.
And if you live in the lower parts of zone 9, officially called zone 9b, then you have a lot more latitude on growing tropicals.
To help you decide what your lowest temperatures might be, we've found several plant hardiness maps that will clearly tell you what to expect when you enter your zip code into the application. If you live near to the edge of a given zone, the maps will argue with each other and some will err on the side of the coldest winters and others the warmest winters --- just take it with a grain of salt and be prepared.
If it does get to the coldest temperatures, it probably won't last very long.