A freeze occurs when temperatures dip to 32 degrees (Fahrenheit) or below. For gardeners, this is the critical threshold — the temperature at which tender plants begin to suffer damage or die. Your last spring freeze date tells you when it’s finally safe to plant warm-season crops. Frost formation can be a bit trickier, since there is no standard definition of what the threshold should be.

Conditions can vary greatly across the state and frost can form when readings dip as low as 32 degrees but can be as high as 37 degrees. So for our purposes, we’ll discuss frosts and freezes as one event, as both can be damaging to early-season gardens.

Here’s the important part: frost dates are based on 30-year historical averages. Those dates are not a guarantee! There’s still a 30% chance of frost after your listed “last spring freeze” date.

North Carolina’s frost dates vary significantly depending on where you live in the state. The Coastal Plain experiences milder conditions and longer growing seasons, with an average last freeze date from late March to early April, while the mountains see later spring thaws with last freeze dates as late as May. Visit NC State Extension for an interactive map with local average last-frost dates, as well as regional crop planting calendars from NC Cooperative Extension.

The time between your last spring freeze and first fall freeze is your growing season — the window when warm-weather plants can thrive. North Carolina’s growing season ranges from about 200 days in the mountains to 250 days in coastal areas. This matters because it helps you choose the right crop varieties, selecting crops that mature within your local growing season.

But not all crops need to wait until after the last freeze. Cool-season vegetables, like lettuce, carrots and onions, are frost-hardy and can actually be planted weeks before your last spring freeze date. These crops thrive in cool soil and can withstand light frosts. Starting them early gives you a jump on the growing season and a spring harvest before summer heat arrives.

Warm-season crops, like tomatoes and squash, are sensitive to frost and cold soil. Planting these too early in cold soil can cause them to rot or fail to germinate. It can be tempting to get started on a 70-degree day in late February, but patience pays off with healthier, more productive plants if you wait until your region is in the safe zone.

Here’s the important part: frost dates are based on 30-year historical averages. Those dates are not a guarantee! There’s still a 30% chance of frost after your listed “last spring freeze” date. What’s more, climate data shows that North Carolina’s growing season is expanding. The last spring freeze is arriving two to three days earlier per decade, while the first fall freeze is occurring about two days later per decade. This means gardeners are getting longer growing seasons — but it also means traditional frost dates may shift over time.

The bottom line? Stay tuned to your local meteorologist as spring approaches and pay close attention to the temperature forecast for guidance. Small shifts in temperature can have big impacts on your garden!