Largo, Florida is in USDA Hardiness Zones 10a.Click to see full answer. Hereof, what zone is St Petersburg FL? Additional Gardening Related Data for Zipcode 33708 – Saint Petersburg, Florida 1990 Hardiness Zone: Zone 9b: 25F to 30F Average First Frost: January 1 – 10 Average Last Frost: January 11 – 20 Koppen-Geiger Climate Zone: Cfa – Humid Subtropical Climate Ecoregion: 75b – Southwestern Florida Flatwoods Subsequently, question is, what zone is Pinellas County? Pinellas County, Florida is in USDA Hardiness Zones 9b and 10a. Also question is, what is the elevation of Largo Florida? 10 m What plant zone is Clearwater Florida? Zones 9b