Frost Dates Guide: First and Last Frost Dates Explained
Your frost dates define your entire planting schedule.
Every planting decision traces back to two numbers: your last spring frost date and your first fall frost date. These define your growing season. Understanding frost dates is the single most important skill in garden planning.
All frost date data from the Plant Anywhere frost date database, covering 9,275 US ZIP codes using 30-year NOAA climate averages.
What Are Frost Dates
Frost dates are statistical averages, not guarantees. Your last spring frost date is the date after which the probability of a killing frost drops below 50 percent, based on 30 years of weather data. Your first fall frost date is when frost becomes more likely than not.
In any given year, the actual last frost might come 2 weeks earlier or later. Experienced gardeners treat frost dates as guidelines. Waiting 1 to 2 weeks after your last frost date substantially reduces risk for warm-season transplants.
Light frost vs. hard freeze
A light frost (32 to 36 degrees F) damages tender warm-season crops but leaves cold-hardy crops unharmed. A hard freeze (below 28 degrees) damages or kills most garden plants.
How to Find Your Frost Dates
1. ZIP code lookup
Enter your ZIP code into the Plant Anywhere frost date finder for your average last spring frost, first fall frost, growing season length, and USDA zone.
2. USDA zone averages
Use the zone-level frost date averages in the table below. Less precise than ZIP-level but sufficient for planning.
3. Local extension office
Your county cooperative extension office publishes frost date information specific to your area.
Frost Dates by USDA Zone
| USDA Zone | Last Spring Frost | First Fall Frost | Growing Season (Days) |
|---|---|---|---|
| Zone 3 | May 15 | Sep 15 | 120 |
| Zone 4 | May 1 | Oct 1 | 150 |
| Zone 5 | Apr 15 | Oct 15 | 180 |
| Zone 6 | Apr 1 | Oct 31 | 210 |
| Zone 7 | Apr 15 | Oct 15 | 180 |
| Zone 8 | Mar 15 | Nov 15 | 245 |
| Zone 9 | Feb 15 | Dec 1 | 290 |
| Zone 10 | Jan 31 | Dec 15 | 320 |
How to Use Your Frost Dates
Warm-season crops
Tomatoes, peppers, squash, beans, cucumbers cannot tolerate frost. Plant 1 to 2 weeks after your last frost date. See the seed starting schedule.
Cool-season crops
Lettuce, peas, spinach, radishes, kale tolerate light frost. Plant 2 to 4 weeks before your last frost date. Plan a second planting 6 to 8 weeks before first fall frost.
Extending the Growing Season
Row covers
Floating row cover provides 2 to 8 degrees F of frost protection. Also blocks insects.
Cold frames
Bottomless box with transparent lid. Extends season 4 to 6 weeks.
Water-filled protectors
Keep plants 10 to 15 degrees warmer. Allow transplanting 3 to 4 weeks early.
Mulch
3 to 4 inches insulates soil and moderates temperature swings. See the watering guide.
Emergency Frost Protection
- Water the soil in the afternoon. Moist soil holds heat.
- Cover plants before sunset with row cover or sheets.
- Avoid plastic directly on plants.
- Remove covers in the morning above 40 degrees.
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Frequently Asked Questions
What is a frost date and why does it matter for gardening?
A frost date is the average date of the last killing frost in spring or the first killing frost in fall, calculated from 30 years of NOAA weather station data. Your last spring frost date and first fall frost date together define your growing season. Every planting decision depends on these two dates: warm-season crops like tomatoes and peppers go in after the last frost, while cool-season crops like lettuce and peas can be planted weeks before it.
How do I find my frost dates by ZIP code?
Enter your ZIP code into Plant Anywhere's frost date finder to see your average last spring frost date, first fall frost date, growing season length in days, and USDA hardiness zone. The tool covers over 9,200 US ZIP codes using 30-year NOAA climate averages. You can also check your county cooperative extension office for locally calibrated frost date information.
Can I plant before my last frost date?
Yes, but only with cool-season crops that tolerate light frost. Lettuce, peas, spinach, radishes, kale, and other cold-hardy vegetables can be planted 2 to 4 weeks before your last frost date. Warm-season crops like tomatoes, peppers, squash, and beans should wait until 1 to 2 weeks after the last frost date, because even a light frost will kill them.
How do I protect my plants from a late frost?
Cover plants with floating row cover or old bedsheets before sunset on nights when frost is forecast. Water the soil in the afternoon, because moist soil retains heat better than dry soil. Row cover provides 2 to 8 degrees Fahrenheit of frost protection depending on weight. Remove covers in the morning once the temperature rises above 40 degrees to prevent overheating.
What is the difference between a frost and a freeze?
A light frost occurs at 32 to 36 degrees Fahrenheit and damages tender warm-season crops like tomatoes, peppers, and basil, but leaves cold-hardy crops like kale and spinach unharmed. A hard freeze occurs below 28 degrees Fahrenheit and can damage or kill most garden plants, including many cold-tolerant varieties. Knowing this difference helps you decide when to harvest and when to protect.
What is a hardiness zone and how does it affect planting?
A USDA hardiness zone is a geographic region defined by its average annual minimum winter temperature. The continental US spans zones 3 through 10. Your zone determines when your frost-free growing season starts and ends, which perennial plants survive your winters, and when to start seeds indoors. Zone 3 gardens may have only 120 frost-free days, while zone 10 gardens enjoy 320 or more.
How accurate are frost date predictions?
Frost dates are 30-year statistical averages, not guarantees for any single year. In a given year the actual last frost may arrive 2 weeks earlier or later than the average. Experienced gardeners treat frost dates as guidelines and add a 1 to 2 week safety margin before transplanting warm-season crops. Checking your local 10-day weather forecast alongside your average frost date gives you the most reliable planting window.