Ask any experienced gardener what drives their planting schedule and the answer is almost always the same: frost dates. Your last spring frost and first fall frost dates define the boundaries of your growing season, and nearly every planting decision flows from them.

What Are Frost Dates?

Frost dates are estimates — based on decades of weather data — of when your area will experience its last freezing temperature in spring and its first freeze in fall. They're expressed as calendar dates with a probability attached (often the 50% probability date).

For example, if your last frost date is April 15, that means there's roughly a 50% chance of a frost occurring after that date. It's a guideline, not a guarantee.

Last Frost Date (Spring)

This is the date that unlocks warm-season planting. Once your last frost date passes, you can generally:

  • Transplant tomatoes, peppers, and eggplant outdoors
  • Direct-sow beans, squash, cucumbers, and corn
  • Move tender herbs like basil outside
  • Set out warm-season flowers

Many gardeners count backward from this date to determine when to start seeds indoors.

First Frost Date (Fall)

This date signals the end of the warm growing season. Use it to:

  • Count backward to determine the latest you can plant a crop and still harvest
  • Plan succession plantings of fast-maturing crops
  • Know when to protect or harvest tender plants
  • Time your fall garden plantings (broccoli, kale, garlic)

Your Frost-Free Window

The number of days between your last spring frost and first fall frost is your frost-free growing season. This number ranges dramatically:

Zone 4 gardeners may have just 120 frost-free days, while Zone 9 gardeners enjoy 270+ days. That difference of 150 days changes everything about what you can grow.

Finding Your Frost Dates

The quickest way is to enter your ZIP code into our Smart Planting Planner. We'll show your estimated last and first frost dates along with crop-specific recommendations.

Remember: frost dates are averages. Watch your local forecast as planting time approaches, and have row covers ready for surprise late frosts. A single night below 32°F can wipe out weeks of work.

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