DibbleA hardiness zone is a shorthand for how cold your winters get. It is based on the average lowest temperature an area sees in a typical year. Colder places have lower numbers, milder places have higher ones. The system runs from roughly zone 3 in cold northern areas up through zone 11 in nearly frost-free regions.
What your zone actually tells you
Your zone answers two practical questions. First, which perennial plants, like fruit trees and shrubs, can survive your winter outdoors. Second, roughly how long and warm your growing season is. A gardener in zone 4 has a short, cool season and starts many crops indoors, while a gardener in zone 9 can grow almost year round.
How to find yours
The easiest way is to look it up by your ZIP or postal code. In Dibble, you enter your code once during setup and the app sets your zone for you, along with your typical frost dates. You can browse every zone calendar here.
From zone to planting dates
Here is the part people miss: your zone does not set your planting dates directly. It points to your typical frost dates, and those frost dates are what each crop is timed against. Tomatoes go out a week or two after your last spring frost. Garlic goes in before your first fall frost. Dibble does this math for every crop so you do not have to.
