Grow · field guide
When to Plant Vegetables: Frost Dates Made Simple
Timing is the difference between a crop and a casualty. Plant tomatoes too early and one late frost kills them; sow lettuce too late and it bolts in the heat. Two dates anchor everything: your last spring frost and your first fall frost. Here is how to use them.
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Frost dates are your starting line
Your last spring frost and first fall frost are averages based on local history, not guarantees. A last frost date is the day past which frost is unlikely, but not impossible, so a cautious week of buffer never hurts for tender crops.
The planner stores both dates for your ZIP and counts each crop's sow date from them, so you do not have to do the math.
Cool-season vs warm-season
Which date a crop keys off depends on whether it shrugs off frost or dies to it:
- Cool-season crops (lettuce, peas, spinach, kale, carrots, broccoli): plant 2 to 6 weeks before the last frost. Light frost does not bother them, and heat makes them bolt.
- Warm-season crops (tomatoes, peppers, beans, squash, cucumbers): plant after the last frost has passed and the soil has warmed.
Watch the soil, not just the air
Warm air does not mean warm soil. Beans and cucumbers sown into cold ground below 60 F often rot instead of sprouting. Soil warms about 2 to 3 weeks behind the air, so even after the last frost, give the ground time. A cheap soil thermometer settles the question.
Fall has a clock too
Fall planting is the part beginners miss. To time it, count back from your first fall frost by the crop's days to maturity, plus a couple of weeks of slower fall growth. That tells you the last day to sow kale, lettuce, or carrots for a fall harvest. The planner flags these dates so the window does not slip past you.
Keep going
Questions, answered straight
They are based on your local weather history by ZIP code. Enter your ZIP in the planner and it gives you both your average last spring frost and first fall frost, then times every crop to them.
Cool-season crops, yes. Lettuce, peas, spinach, and kale handle light frost and can go in 2 to 6 weeks early. Warm-season crops like tomatoes must wait until after the last frost.
The soil was too cold. Beans and cucumbers need soil above 60 F, which lags 2 to 3 weeks behind warm air. Wait for the ground to warm or use a soil thermometer.
No. It is the average date past which frost is unlikely, roughly a 50-50 mark in the historical record. For tender crops, waiting an extra week past it is cheap insurance.
Know when it's time to plant
Give us your ZIP and we'll email you a planting checklist for your exact frost dates, this month's list right now, then once a month when sow windows open.
One email a month, only when there's something to plant. Unsubscribe anytime.