Garden planting calendar: every sowing date from your frost date
Every planting date in a vegetable garden hangs off one number: your average last spring frost. Enter it, tick the crops you're growing, and get the whole season in order — what to start indoors and when, when to begin hardening off, and when it's actually safe to put plants in the ground. Turn on the fall module and it counts backward from your first frost too.
Tick items off as you go — your dates and progress save automatically on this device, so come back any time to pick up where you left off.
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Your hardiness zone is not your frost date
This trips up almost everyone, so it's worth being blunt. USDA plant hardiness zones are built from the average annual extreme minimum winter temperature — they tell you which perennials survive your winter, and nothing else. They carry no frost-date, growing season, or summer-heat information at all. Coastal Seattle and interior Virginia are both roughly zone 8a with meaningfully different frost dates.
Zones do matter — just for a different question. They tell you whichperennials survive your winter: fruit trees, berries, asparagus, rhubarb, perennial herbs. Annual vegetables never experience winter, so a tomato is indifferent to your January low. That's why this calculator asks for your frost date rather than your zone: there is no honest way to convert one into the other. Any chart promising "frost dates by zone" is inventing them. Get yours fromNOAA's climate normals (1991–2020, about 15,000 stations) or your state extension service, both linked in the sources below.
What actually limits what you can grow: season length
Zones get blamed for this, but the real constraint on a vegetable garden is your growing season length — the number of frost-free days between your last spring frost and your first fall frost. Count the days between those two dates, then compare that against the "days to maturity" printed on the seed packet, leaving a couple of weeks of slack because growth slows as autumn light fades.
If a crop needs more days than you have, you have three honest options: choose a short-season variety (many tomatoes, melons and pumpkins come in 60–70 day versions bred exactly for this), start it indoors to buy a head start, or skip it. A 95-day season will not ripen a 110-day pumpkin outdoors no matter what your zone map says. This is also why days-to- maturity belongs to the variety, not the crop — and why we point you at your seed packet rather than printing one number per vegetable.
One trap when reading those numbers: seed catalogues anchor "days to maturity" inconsistently. Some count from direct sowing, some from transplanting, and some — for fruiting crops like tomatoes, peppers and melons — count from flowering. A "35 day" pepper is 35 days from bloom, not from seed. Check which the packet means before you count backward.
Frost dates are probabilities, not a day on the calendar
NOAA publishes freeze dates at nine probability levels. The50% date is the median — frost arrives later than that in half of years. The 10% date is later and more conservative: frost comes after it only about one year in ten. For frost-tender crops like tomatoes, peppers and basil, planning to the 10% date is cheap insurance; a single late frost ends those plants. For hardy crops that shrug off a light freeze, the median is fine. NC State adds the honest caveat that these are best guesses drawn from past trends, which may not match the season you're actually in.
Hardening off: 7 to 14 days, and don't skip it
Seedlings raised indoors have never met wind or direct sun. SDSU Extension puts the transition at seven to fourteen days (UMN says two weeks): start with three or four hours outside in a sheltered spot during the warmest part of the day, increase the exposure daily, and finish with a full 24 hours out before planting. Ease off watering without letting plants wilt, and bring them in if the day stays below 45°F. One worthwhile disagreement: Cornell advises hardening tomatoes by dialing back water and fertilizer rather than by chilling them, since cold stress can stunt the plants and cause catfacing.
Fall planting runs the math backward
Spring planting counts forward from the last frost; fall planting counts backward from the first. University of Maryland's formula is simple: take the crop's days to maturity, add 10–14 days as a "short day factor" for slower autumn growth, and sow that many days before your first frost date. Frost tolerance then decides whether that deadline is hard. Tender crops like beans have no tolerance and must finish first. Semi-hardy crops such as broccoli and lettuce take the upper 20s°F. Hardy crops — kale, carrots, spinach — handle the mid-to-low 20s and can keep growing well past your frost date, which is why fall carrots and kale are often better than the spring crop.
Two crops we deliberately left off
You won't find peas or sweet corn on the calendar. No extension source gives either one a dependable offset from the frost date, because they're governed by soil rather than air: peas go in "as soon as the soil thaws and is workable," and sweet corn wants soil around 60°F. Inventing a week number for them would look precise and be wrong, so we left them out and recommend a soil thermometer instead. For the same reason, every date here is a window rather than a single day — the underlying extension guidance is a range, and sources genuinely differ (indoor sowing for eggplant runs anywhere from 6 to 10 weeks depending on who you ask).
Verify with the official sources
Every date on this page is drawn from the sources below. Rules and fees change — check these directly for your own situation before you rely on any deadline here.
- UNH Extension — Growing Vegetables: When to Plant Your Vegetable Garden
- Utah State University Extension — Suggested Vegetable Planting Dates
- University of Maryland Extension — Planting Dates for Vegetable Crops (fall formula)
- Iowa State Extension — Fall Planting of Vegetables (frost tolerance classes)
- SDSU Extension — Harden Your Transplants Prior to Planting
- USDA — Plant Hardiness Zone Map: How to Use the Maps
- NOAA NCEI — U.S. Climate Normals (freeze/frost dates)
- NC State Extension — Interpreting Freeze/Frost Probabilities
Sources last verified: 2026-07-17
Frequently asked questions
Can I use my USDA hardiness zone to find my frost dates?
No — and this is the single most common garden-planning mistake. USDA plant hardiness zones are based on the average annual extreme minimum WINTER temperature, and describe which perennials survive your winter. They contain no frost-date, growing-season or summer-heat information. Coastal Seattle and interior Virginia are both roughly zone 8a with materially different frost dates. Look up frost dates for your actual location from NOAA's climate normals or your state extension service.
Do I need to know my hardiness zone to use this?
No — and for vegetables it wouldn't help much anyway. USDA hardiness zones are built from the average annual minimum WINTER temperature, so they tell you which perennials survive your winter: fruit trees, berries, asparagus, rhubarb, perennial herbs. Annual vegetables never experience winter — they're sown and harvested within a single season — so what limits them is your frost dates and the length of your growing season, not your zone. Two gardens in the same zone can have very different planting calendars.
What actually decides whether I can grow a crop?
Your growing season length — the number of frost-free days between your last spring frost and your first fall frost. Count the days between those two dates and compare it against the 'days to maturity' on the seed packet, allowing a couple of weeks of slack for slower autumn growth. If the crop needs more days than you have, either pick a short-season variety (many tomatoes, melons and pumpkins come in 60–70 day versions) or start it indoors to buy a head start. A 95-day season simply won't ripen a 110-day pumpkin outdoors, whatever your zone says.
How do I find my last frost date?
NOAA's National Centers for Environmental Information publishes freeze and frost probabilities from about 15,000 stations using 1991–2020 normals, and most state extension services republish them locally. They're given as probabilities rather than a single day: the 50% date is the median, while the 10% date is later and safer for frost-tender crops like tomatoes and basil. NC State notes these are best guesses from past trends, not guarantees.
When should I start tomato seeds indoors?
About 5–7 weeks before your last frost date. Tomatoes need 6–8 weeks from seed to transplant and go out 1–2 weeks after the frost date. Starting much earlier backfires — you end up with leggy, root-bound seedlings that transplant poorly.
How long does hardening off take?
Seven to fourteen days per SDSU Extension (UMN says two weeks). Start with 3–4 hours outdoors in a sheltered spot during the warmest part of the day, increase daily, and finish with a full 24 hours outside. Bring plants in if daytime temperatures fall below 45°F. One nuance: Cornell advises hardening tomatoes by reducing water and fertilizer rather than exposing them to cold, which can stunt them.
How do I calculate fall planting dates?
Count backward from your first fall frost. University of Maryland's formula: take the days to maturity for the crop, add 10–14 days as a 'short day factor' to account for slower autumn growth, and plant that many days before your first frost date. Hardy crops like kale, carrots and spinach tolerate frost and can keep growing past that date; tender crops like beans must finish before it.
Why aren't peas and sweet corn on the calendar?
Because no extension source gives them a reliable frost-date offset — they're anchored to soil condition instead. Peas go in 'as soon as the soil thaws and is workable,' and sweet corn wants soil around 60°F. We'd rather leave them off than invent a date that looks precise and isn't. Use a soil thermometer and sow on the soil's schedule.
Why are the dates shown as ranges?
Because the underlying guidance is a range, and extension services genuinely differ — indoor sowing times for eggplant run 6–10 weeks depending on who you ask. Showing a single false-precision date would hide that. Treat the window as the planting period and use your seed packet, which is cultivar-specific, to fine-tune.
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