When to Plant Pumpkins: Count Back From Halloween, Not Forward From Frost

Plant pumpkins after the last frost, once the soil is at least 65°F, and count back from Halloween: sow about 90 to 120 days before October 31, which is July 3 to August 2, unless your median first frost comes sooner. In Chicago a 100-day pumpkin can go in from May 26 to July 23; in Minneapolis only from June 4 to July 8.

Extension sources agree on the warmth rule and on 90 to 120 days to maturity, then give windows that run from late May to early July without saying where each one applies. We turned each rule into dates using NOAA 1991–2020 normals¹ for 37,563 lower-48 ZIP codes, built tables for 24 cities and set 14 published local dates beside them. Everything uses air temperature as a stand-in for soil temperature, because our NOAA data has no soil readings. Ripeness signs, the hard-freeze line and curing are in our guide to when to harvest pumpkins.

When the ground is warm enough to sow

Pumpkins are tender. Penn State’s commercial guide says plants and fruit show injury from even a slight frost and that growth slows below 50°F,³ and the extension sources set the soil line in three places. Penn State’s garden guide says soil should be at least 65°F for germination,² as do Utah State and the University of Arkansas.^4,5 Clemson, the University of New Hampshire and Penn State’s commercial guide use 60°F,^8,9,3 and Nebraska and Mississippi State say 70°F.^7,15 Oregon State’s germination table lists a 60°F minimum and a 70 to 90°F optimum range.¹⁰ Cornell’s growing guide gives 65°F as the minimum and 70°F as the preference, then adds a calendar shortcut:⁶

or about 2 weeks after the last frost date

We tested the shortcut. Each date in Table 1 is the latest of three: our 10% last-frost date, the day the normal daily mean air temperature reaches 65°F, and the day the normal daily low reaches 50°F. Measure the real thing before you sow: Penn State takes soil temperature three inches down and Clemson four.^3,8

Warmth, not frost, sets the date

Across the 36,271 ZIP codes whose normals reach both lines, the 65°F air mean sets the date in 94.2%, the 50°F night in 4.9% and the frost date in only 0.9%. Our date falls a median 37 days after the median last frost (middle half 33 to 42), so Cornell’s two-weeks-after shortcut points to an earlier date than the warmth lines in all but 7 of those ZIP codes, by a week or more in 99.4%. In Chicago the gap is 32 days, in Boston 49 and in Salt Lake City 41.

The result does not hinge on the 65°F line. At the 60°F line the shortcut is still earlier in 99.9%, and by a week or more in 83.0%. At 70°F our date moves a median 19 days later, and 15.4% of ZIP codes never reach it. The median first-sowing date is May 25, on or before it in 51.6% of ZIP codes and after June 15 in 13.3%. The rule is the same as in our cucumber guide; pumpkins differ in what comes next, because the finish line is Halloween.

Count back from Halloween: the last sowing date

Most gardeners want a pumpkin for October 31, and the sources count back from it. The University of Arkansas says pumpkins need 90 to 120 days, about 100 for a medium carving type such as Spirit and 120 for a large one such as Big Moon, and gives a rule of thumb:⁵

plant your pumpkins and then invite your guests back for Halloween to harvest

The other calendars cluster around the same weeks: Clemson says to plant most varieties by early July,⁸ UF/IFAS by early July,¹⁶ Mississippi State early to mid-July¹⁵ and LSU mid to late July, with the third week better and the end of July the limit.¹⁴ Illinois Extension runs from late May in the north to early July in the far south.¹¹ Counting back from October 31, a 120-day pumpkin goes in by July 3, a 100-day by July 23 and a 90-day by August 2.

Frost moves that earlier. Arkansas warns that planting too late risks frost damage,⁵ and in 62.7% of lower-48 ZIP codes the median first frost comes before Halloween, the same figure as in our harvest guide. Table 2 therefore counts back from the earlier of Halloween and the median first 32°F frost. Across all ZIP codes the median last sowing date is June 26 for a 120-day pumpkin, July 16 for a 100-day and July 26 for a 90-day.

The Fourth of July rule, tested

Arkansas’s rhyme is a southern rule. Where frost comes before Halloween, the count-back date moves into June: for a 120-day pumpkin, June 18 in Minneapolis and June 14 in Denver and Boise, against July 3 in Chicago and Dallas. Nationally, a pumpkin sown July 4 ripens after the median first frost in 64.5% of ZIP codes if it takes 120 days, in 22.5% if it takes 100 and in 9.2% if it takes 90. Sown August 1, even a 90-day pumpkin ripens after the median frost in 60.9%. Chicago, New York and the Gulf Coast are exceptions where Halloween, not frost, sets the date.

Planting too early: pumpkins that ripen in August

A May sowing is not safer. Illinois Extension says so directly:¹¹

If pumpkins are planted too early, they may soften and rot before Halloween.

Epic Gardening tells readers to start no later than the beginning of June and ideally by May for Halloween.²¹ On our numbers that is early for most places. A 100-day pumpkin sown on the first warm day ripens a median September 2, and 30 or more days before Halloween in 91.3% of ZIP codes and 60 or more in 49.8%. In Raleigh it is ripe August 9, in Chicago September 3 and in Dallas July 16. The Old Farmer’s Almanac sets the late limit instead: seeds in by late May in northern climates, or as late as early July in the deep South, should leave most varieties time to mature before frost.²⁰

The sweet spot is a sowing date that ripens the fruit in the last weeks before Halloween, not on the earliest warm day. Our harvest guide covers curing and storing a pumpkin that is ready early.

Short seasons in the North and mountain West

In cold places the window is short. A pumpkin sown on the first warm day ripens after the median first frost in 3.2% of ZIP codes if it takes 90 days, 6.6% if it takes 100 and 16.6% if it takes 120, and a further 11.8% of 120-day sowings leave less than two weeks to spare. Concord, New Hampshire, opens June 13 and has a median first frost on October 3, so a 100-day pumpkin has 12 days to go in and a 120-day pumpkin cannot fit in the median year. Boise has 11 days, and Minneapolis and Denver 34.

The sources offer four ways to buy time. Choose a shorter variety: Arkansas lists 90-day types for pies and decorating.⁵ Start seeds indoors: Cornell and Iowa State say to start them 3 to 4 weeks before planting out,^6,12 though Arkansas does not recommend transplanting because of the taproot⁵ and UNH says pumpkins dislike root disturbance.⁹ Use plastic: Penn State says plastic mulch warms soil 8 to 12 degrees over bare soil,³ and Utah State says plastic and row covers allow seeds or plants to go out two weeks before the last frost.⁴ Our dates assume no cover. On the Pacific coast the limit is warmth, not frost: Portland opens June 25 and Seattle June 30, and their first frosts come in December and November.

Hot summers and planting into July

Penn State gives 65 to 95°F as the best growing range and says growth and maturity slow above 95°F.³ Oregon State’s table puts the germination maximum at 100°F.¹⁰ In Texas, Texas A&M AgriLife says pumpkins thrive in early summers there and puts the best planting from early May through June.¹⁸ In 5.2% of ZIP codes the normal daily high on the 100-day count-back date, July 23, is 95°F or more, and in 24.7% it is 90°F or more; Dallas is at 97.0°F and Columbia, South Carolina, at 95.1°F. These are normals, and individual days run hotter.

Frost-free ZIP codes have no frost count, so use the months: Phoenix (ZIP 85001) has normal highs of 95°F or more from June through September. Florida’s advice conflicts on a single page: UF/IFAS Gardening Solutions says to plant by early July for Halloween, and also that pumpkins do best planted in late March and early April, with later plantings smaller and more affected by virus and fungal disease.¹⁶ North Florida’s county office says early July for Halloween.¹⁷ Our table has no frost dates for 104 of Hawaii’s 135 ZIP codes, so we give no Hawaii dates.

What extension sources say, side by side

Table 3 lines up the published rules. Soil lines range from 60 to 70°F and calendars from late May in the north to mid-July in the Gulf states, which is why a single rule cannot work everywhere.

How published local calendars compare

Fourteen published dates from 12 extension offices could be converted; Table 4 sets each beside ours. Our spring dates sit inside the ranges of Illinois, Penn State and Colorado State, nine days after Iowa State’s mid-May, three days after the end of New Hampshire’s range and four days before Texas A&M’s early May. For the Halloween rows we compare against our count-back range of 120 to 90 days. The southern windows begin at or before our 120-day date, and Georgia’s calendar for an early October harvest falls inside our count-back from October 1.¹³ Iowa State’s mid-June last practical date is a week before our 120-day date in Des Moines.

How we calculated these dates

Daily temperatures are NOAA’s monthly normals placed on the 15th of each month and interpolated linearly, for the station nearest each ZIP code.¹ Frost dates are the median and 10% 32°F dates. The 65°F and 50°F lines come from the sources above and are applied to air temperature, not soil. Last sowing is October 31 or the median first frost, whichever is earlier, minus the days to maturity; it assumes no slowdown in cool autumn weather, which the sources do not quantify. Individual years vary by weeks, and the seed packet’s number is a guide, not a promise. The USDA hardiness zone map cannot decide any of this: it is based on the average annual extreme minimum winter temperature.²²

Next steps

Look up your own dates with our frost date lookup and read what a last frost date means. Pumpkins share their warm-soil start with cucumbers and tomatoes; green beans use a lower 60°F soil line. To start seeds indoors, count back on our seed-starting guide, and for late sowings use the formula in our fall vegetable planting guide. Cover young vines on a cold night using our frost-cover guide, and see more crops in our vegetable guides.