Frost Date & Seed Starting Calculator
Enter your average frost dates once and get a personalized sowing calendar for 24 common crops, updated automatically all season.
Your sowing calendar
Dates calculated from your last spring frost above.
About this frost date calculator
Enter your average last spring frost date and first fall frost date once — these repeat every year, so there's nothing to redo next season. From those two dates, the tool works out your current growing season length, how many days remain until the next relevant frost, and a full personalized sowing calendar for 24 common vegetables and flowers, each with its own recommended start-indoors or direct-sow offset from your last frost date.
The sowing calendar updates automatically based on today's date, sorting every crop by when it should actually happen and flagging what's due now, what's still upcoming, and what's already passed for the season. Don't know your local frost dates offhand? A quick search for "[your town] average last frost date" usually turns up an answer from a local extension office or almanac site in under a minute, and works the same way whether you're in the northern or southern hemisphere.
The offsets built into each crop are general guidelines, not fixed rules for your exact variety — some cultivars want more or less lead time than the average, so check your seed packet when it disagrees with the calendar here.
Frost dates are themselves averages, not guarantees; an unusually late or early frost can still happen in any given year, so it's worth keeping some frost cover on hand near the edges of the season regardless of what the calendar says. Your dates are saved locally in your browser so they carry over automatically.
Frequently asked questions
Do I need to re-enter my frost dates every year?
No, enter them once. They're saved locally in your browser and reused automatically every season, since your average frost dates don't change year to year.
I don't know my local frost dates — how do I find them?
Search "[your town] average last frost date." Most gardeners find an answer from a local extension office or almanac site within a minute.
Does this work in the southern hemisphere?
Yes. The calculator works from whatever last-spring and first-fall dates you enter, regardless of which months those fall in, so it adapts automatically to either hemisphere.
Are the sowing offsets exact for every variety?
They're general guidelines. Some cultivars want more or less lead time than the average shown here, so check your seed packet if it gives a different recommendation.
What if there's a late frost after the calculator says it's safe?
Frost dates are averages, not guarantees — an unusually late or early frost can still happen. Keep some frost cover on hand near the edges of the season as a precaution.