The two dates that organize everything else
Nearly every planting decision is counted from one of two anchors: the average last spring frost (when it’s safe-ish to plant tender crops) and the average first fall frost (the deadline everything must beat). The stretch between them is your growing season — anywhere from 70 days in interior Alaska to effectively year-round in South Florida.
These dates are medians from 30 years of records (1991–2020 climate normals), so each carries about a coin-flip’s chance of frost beyond it. That’s why seasoned gardeners plant hardy crops right on the dates but give tomatoes and basil an extra week or two of cushion.
What survives what
| Temperature | What it means | Casualties |
|---|---|---|
| 36–33°F | Light frost possible in low spots | Basil blackens; squash and tomato leaves scorch |
| 32–29°F | Frost / light freeze | All tender crops without cover; peppers, cucumbers, melons |
| 28–25°F | Hard freeze | Half-hardy crops — lettuce, chard, potatoes’ top growth |
| Below 25°F | Killing freeze | Most everything except kale, spinach, collards, carrots, garlic |
From dates to a planting plan
Once you have your two dates, the rest is arithmetic — and we’ve done it for you. The planting calendar turns your zone or frost dates into seed-start, transplant, and direct-sow windows for 50 crops, and the seed starting scheduler builds a printable count-back schedule for your seed rack. For city-by-city guides, browse frost dates by state.
Frequently asked questions
What exactly is a "last frost date"?
It’s the median date of the last spring freeze (32°F) from 30 years of climate records — meaning there’s roughly a 50% chance of frost after that date. It’s a planning anchor, not a guarantee: tender crops usually go out 1–2 weeks after it to shrink that risk.
How accurate are frost dates for my exact garden?
City-level dates get you close, but frost is hyper-local. Low spots, valley floors, and open rural areas frost earlier; urban cores, south slopes, and spots near water frost later — differences of a week or more within a few miles are normal. Use the date as a baseline and adjust for your microclimate.
What’s the difference between a frost and a freeze?
A light frost (36–32°F) nips tender plants like basil and tomatoes but spares hardy greens. A freeze (32–28°F) kills unprotected tender crops, and a hard freeze (below 28°F) ends the season for everything but the hardiest vegetables like kale, spinach, and carrots.
How should I use these dates to plan planting?
Count backwards and forwards from them. Seeds started indoors are timed 4–10 weeks before the last frost, direct-sown cool crops go in 2–6 weeks before it, and tender transplants go out 1–3 weeks after. Our planting calendar does the counting for you.