Hi Tom,

There must be areas of Pinellas that are definitely zone 10 as well as some that are 9b. I know that in some areas close to the water there are coconut palms which you don't see in areas away from the water.

I live in the Kenwood neighborhood of St Pete (around 5th Ave/28th St). I'm 2 miles from Tampa Bay and 5 miles from the Gulf. We've had 1 frost in the 7 winters I've lived here. That frost killed my impatiens and defoliated a jatropha (which recovered) in a neighbor's yard.

I lived in another area of St Pete much closer to the bay before that for 7 years and I remember one hard freeze - I'm guessing it must have been the winter of 1995 - that killed a potted ficus on the patio and also killed a small palm of some sort that was planted in the ground by the patio.

John

For several years I have planted figuring I am in zone 10 or a high zone 9. Anything you might read about a plant doing well in full sun for zone 9, forget it. If the description says partial shade zone 9, use filtered shade in St Pete. We have had several frosts back ten or so years ago and in 1989 at Christmas time even a light snow for a few hours.

I would recommend using zone 9 with extreme caution. A few hours of cold doesn't hurt most plants as much as 6-8 hours of that direct sunshine that brought most of us to FL in the first place.

I agree with your conclusion. If you look at the various Hardiness Zone Maps and the tropical plants that thrive in much of the Clearwater/St. Petersburg peninsula, you have to be in Zone 10.

Here is a link that might be useful: Hardiness Zone Maps of Florida

Yeah, Pinellas county is basically an island in the Gulf of Mexico. You all are pretty much in the tropics.

bsewall, thanks for that link. Quite informative!

I'm sure this will inspire a lively discussion of contesting accounts of temperature. I guess I'll start it :)

I live in North Tampa. I've always considered this area to be 9a/9b borderline. Last winter it got down into the mid 20's. No matter how you slice it, that ain't no zone 10.
According to the updated Arbor Day map, I basically live just inside zone 10.

Another example is the difference between where I live and where my dad lives, in Brandon. Up here, I've got lots of tropical things that do not grow as well if at all out in Brandon. My dad is a gardener and has tried many of the plants that I can successfully grow. The winters there damage or kill them, even with protection. So it is curious how the updated Arbor Day map includes the Brandon area East of Tampa in zone 10.

I'm sure the people who put these maps together were using reliable data. But I think the important thing to remember is that these are AVERAGES and GENERALIZATIONS. Freak weather events can always happen. The second I start to fancy myself as firmly zone 10, we will get a bitter cold snap like last year. I swear, the X-mas lights still being up really helped out some of my plants back in January :)

Hi
Would have to agree with the others lol I'm in Palm Beach county and I'll never forget the 24 dgree morning in

82. Thought I was going to die .BIG difference between frost and hard freeze lol Or how about the "snow of 78 made it all the way to Miami. No 10 that year. for the entire state
    Of course if you look at records you find the only "frost" free place in the 48 is Key West, Even there it's been in the low 40's lol.
    If Ma nature wants to send the jetstream south it WILL get cold lol. May not happen again for 20 years but it will happen eventually lol gary

Bsewall - Thanks for that link to the history of Zone updates, it adds an interesting perspective to things.

Musicman - I'd agree with you. Although I grew up in Pinellas County I lived in N. Tampa while working on my first degree at USF, then moved to Brandon for a few years before getting back to the water. Definitely lost a few tropical's in Brandon...and I do remember The Big Chill (01-19-1977), quarter inch of snow on the ground and flurries until 02:00 PM in N. Tampa. I'd say Brandon falls in Zones established in the earlier maps, perhaps the 1995 or 2003 update...definitely not a Zone 10.

We moved to Bradenton in 1984, back then it really was zone 9 temperatures but now the majority of the time I consider us to be zone 10a. I did cover the tomatoes twice this past winter and should have once the winter of 2006/2007 but we don't get the freezes we used to here. But about 5 or 6 years ago it was in the 40s/low 50s all day long most of the winter season. It's warm enough that we start letting ourselves Zone Creep then we get enough cold to remind us we're still in Central Florida. Suzanne

FYI - I live in Lithia, south of Brandon, and I couldn't agree more that we are in Zone 9, despite what several of the maps suggest. When I put a plant in the ground I assume it and I will have to live by the rules of Zone 9 - expect a minimum of one or two killing frosts each year and forget about planting a Mango plant in the backyard.

What I find really intriguing is that everyone on this thread agrees about what should be the hardiness zone designations for this area of Central Florida. But none of the official sources for the Hardiness Zones can agree amongst themselves. So I basically ignore the maps. Apologies to Bob Dylan - You don't need a weatherman to know how cold the wind blows.

I had hoped that some of this confusion would be resolved with a new project by the USDA to update the official Hardiness Zone Map for the US. The project was supposed to be completed earlier this year, but if you look on their web site, it now says a new map won't be available until 2009. That just confuses me further. Hardiness Zone Maps are just compilations of existing data. It should be a relatively simple data crunching exercise, not some drawn out process.

But so what? I'm resigned to accepting I live in Zone 9, regardless of what the maps say or don't say.

Here is a link that might be useful: Hardiness Zone Update

I also meant to respond to John's observations above about the coconut trees. My neighbors on both sides have had fruiting coconuts palms for many years, although one pulled his out to put in a swimming pool the other neighbors coconut palm is absolutely loaded with fruit.

I'm on Davis Islands and I "usually" go by the rule of Zone 9 even with a micro-climate (surrounded by water). With all the talk of changing our zone to 10, I'm afraid many folks are going to be VERY UPSET when their "tropicals" become freeze/frost damaged. That being said, I still try and have been successful with coconuts and sapodilla and mango and lychee, et. all with the understanding that when the "big one comes"...if I don't heat and cover...they are dead.

Tampaart - good point, and everything is relative. I think in the 50s-70s when there was still a lot of Pinellas County (PC) still undeveloped heat was readily absorbed and radiated at night, but somehow now that we are one big asphalt and concrete jungle I'm not sure I understand the change in chilling patterns over the last few decades but it is clear that we do not get the chill we used to. Areas east of you are still relatively undeveloped by our terms over here in PC, and I suspect you're right about what will happen over there...I remember my father going out to drain the radiator on our Ford Falcon (early 60's) because we didn't have antifreeze in it and the temp dropped to 17F. I doubt PC will ever see 17F again, and as every square inch of Florida is developed (unless we run out of water to drink) we'll probably continue to see things change, but for now areas that are still considerably undeveloped are vulnerable....

Thanks for the information. When I was trying to figure out my zone before I came to these forums I found some sites that said 9, others that said 9B and another that said 10. Since there were more 9's I went with that but I still tend to look for plants that are hardy to at least zone 10. Maybe I should look for hardy to zone 11 to take into account future global warming?

I guess I'll change my zone now.

I'm in Holiday, right over the Pinellas/Pasco line and I think we are more a 9b than a 9a, but every place has it's own little microclimates. Up in PA, we lived in a 1 mile square town. My parents were on the other side of town from us and it was a whole 'nother climate in the winter. They would get wind that would knock you off your feet! You could actually feel that it was colder by their house than by ours! Strange.

A little while ago, I averaged out all the lows for the St. Pete weather station (Albert Whitted AP) that were available online (dating back to 1948). The average low during this 60 year period was 35F. A trendline fitted to this data does show an increase in the average low over the past 60 years.

However, the things to keep in mind are---

This is BY FAR the warmest reading official station in Pinellas as the measuring location is at Albert Whitted AP which sits literally IN the Bay. 95% of Pinellas is not as warm as this station. Some areas of Pinellas are 10F+ colder on radiational cooling nights.

There were a number of bad years thrown in this time period, but also enough really good ones to have the average be a low 10b. The pessimistic view is that one night of 9a ruins 20 years worth of 10b palm/plant growth. That is the central Florida curse! When the really bad windy cold fronts come through, water proximity is of little value.

Also, although the average lows of the warmest areas of Pinellas may approach those of some South FL locations, the winter daytime heating is notably less.

But, Ive ignored all the "what ifs" and have planted my yard as though 10a will be the norm :-)

Hey julieyankfan...we are neighbors! I'm up the 19 in NPR!

tom, I have been in Florida 43.10 yrs and it just gets hotter every year. There is nothing cold about our winter (I use that term cautiously!) The rare occasion that we get a "frost" or "hard freeze" has me jumpin' up and down in the street! I miss the old winters with the comfortable cold weather!

Happy Gardening!
Floridian Kim

Larry,

That is a fantastic chart! Next time you get over my way, I'd love your opinion on where to fit my own weather station.

JG

Spockvr6 - outstanding review, thanks. I grew up off old Ridge Rd and Ulmerton, up on the ridge at an elevation of 55'; we were usually 10 degrees cooler than down there on the water. Having said that, I still remember seeing all the tropical's out on the barrier islands die off once in the 60s but thought it was 66' or 67' but from your chart it may have been in the early 60s.

Kim - I still love my fireplace, just let the temp drop below 50F and watch how fast I build a fire...regarding the heat, you sure it isn't us just aging? In my 20s I didn't think anything about going out to play three hours of tennis from 1100-1400 during the middle of summer, now during those hours you'll catch me chilling in the pool ;-)

Junglegal-

No problem on the weather station siting. Ive had a few different stations over the years. What unit did you get? If its PC connectable, youll be able to upload to weatherunderground (which is a fantastic way to share and store your data). My station data is reported here----

Here is a link that might be useful: Tarpon Springs - Harbor Oaks - Alternate US 19, Tarpon Springs, Florida (PWS)

tomncath-

Yes..it was probably 1962 that you recall seeing all the tropicals wiped out as that was when St. Pete (Albert Whitted) logged 22F (their all time low). I have talked with nurserymen located in other areas of Pinellas who claim to have measured as low as 13F during that event!

Bingo! That was it Larry, thanks. Scary to think what that would do to us now....

Well, I'm convinced...I changed my zone to 10a!

"Well, I'm convinced...I changed my zone to 10a!"

Of course, you know that means that youll jinx yourself with a bad fereze next winter! LOL

And all of us too....

I was born & raised in Clearwater and remember the 1962 freeze very well. My dad's huge avocado tree, which he called "Bozo", was killed, and it broke my dad's heart! I grew up eating the most wonderful avocados I've ever had - they were 10" - 12" long, and absolutely delicious. Dad tried growing some more cold-hardy avocados after that, but it was never the same.

Margie

Spockvr6, your graph inspired me. I went out to NOAA and found data on the number of days per year with temperatures less than 32 degrees for Tampa and St. Petersburg. Based on this data St. Petersburg experiences a freeze once every two years, on average, while Tampa gets whomped 2.3 times a year. If you put the data in a graph it clearly shows that while the two cities are only 15 miles apart, their climates are significantly different.

{{gwi:910794}}

bsewall-

Great comparison!

yes...these two areas are wildly different when it come to freezes. The Tampa data comes from the airport, which is located north of Tampa Bay. So, when the cold fronts roll down from the north, the bay cant help anywhere near as much as it does for the St. Pete station, which as I mentioned above, is located literally in Tampa Bay on the south east part of Pinellas.

Here are a few more plots to further illustrate your point. They come from the Southeast Climate center as show the probability of going 365 days in a row without the temperature dropping below a certain value. As can be seen in these charts, there is an 80% chance of going 365 without the temp dropping below 36F at the St. Pete station, but only a 30% chance of that happening at the Tampa AP. What I really like about these charts is that they are based on really long term data (since 1900 for Tampa and 1948 for St. Pete).

Thanks guys and gals for some truly impressive posts. For those of you in the north part of the county and up on the central ridge, please be cautious interpreting this data....