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Seed Starting Calendar for Pennsylvania

Median last frost from Apr 9 to May 17 across Pennsylvania

NOAA stations
157
Median last frost, Pittsburgh
Apr 18
Passed in 9 of 10 years
May 6
Last frost

Last spring frost dates in Pennsylvania

Philadelphia reaches its median last frost around Mar 30, Pittsburgh around Apr 18, Altoona and Selinsgrove in late April, and Bradford on the northern plateau around May 18.

Three dates per station from the NOAA 1991 to 2020 normals. The median is the date half of springs run past. The last column is the date the last 32°F night has passed by in 9 years out of 10, the one to hold tender transplants for.

StationElevationEarly (1 in 10 years later than this)Median last frostPassed in 9 of 10 yearsMedian first fall frost
PhiladelphiaPhila Franklin Inst, USC0036688660 ftMar 15Mar 30Apr 12Nov 17
PittsburghPittsburgh Allegheny County Airport, USW000147621,248 ftApr 2Apr 18May 6Oct 28
Altoona Blair County AirportAltoona Blair County Airport, USW000147361,480 ftApr 8Apr 23May 11Oct 21
Selinsgrove Penn Vly AirportSelinsgrove Penn Vly Airport, USW00014770444 ftApr 13Apr 27May 12Oct 16
BradfordBradford 4SW Rsch 5, USC003608681,660 ftApr 30May 18May 31Oct 4
Crop chart

When to start seeds in Pennsylvania, spring 2027

Counted back from the median last frost at Pittsburgh, April 18. Pick another station to redraw the chart for it.

Seed starting calendar for Pittsburgh, Pennsylvania, spring 2027JanFebMarAprMayOnion (from seed)Onion (from seed): start indoors Jan 10 to Jan 24Onion (from seed): harden off Mar 7 to Mar 21Onion (from seed): set out Mar 21 to Mar 28PepperPepper: start indoors Feb 21 to Mar 7Pepper: harden off Apr 18 to May 2Pepper: set out May 2 to May 9EggplantEggplant: start indoors Feb 21 to Mar 7Eggplant: harden off Apr 18 to May 2Eggplant: set out May 2 to May 9TomatoTomato: start indoors Feb 28 to Mar 14Tomato: harden off Apr 11 to Apr 25Tomato: set out Apr 25 to May 2BroccoliBroccoli: start indoors Feb 7 to Feb 21Broccoli: harden off Mar 7 to Mar 21Broccoli: set out Mar 21 to Apr 4CabbageCabbage: start indoors Feb 7 to Feb 21Cabbage: harden off Mar 7 to Mar 21Cabbage: set out Mar 21 to Mar 28LettuceLettuce: start indoors Feb 14 to Feb 21Lettuce: harden off Mar 7 to Mar 21Lettuce: set out Mar 21 to Mar 28BasilBasil: start indoors Mar 7 to Mar 21Basil: harden off Apr 18 to May 2Basil: set out May 2 to May 9CucumberCucumber: start indoors Mar 28 to Apr 4Cucumber: harden off Apr 11 to Apr 25Cucumber: set out Apr 25 to May 2Cucumber: sow outdoors Apr 18 to Apr 25Summer squashSummer squash: start indoors Apr 4 to Apr 11Summer squash: harden off Apr 18 to May 2Summer squash: set out May 2 to May 9Summer squash: sow outdoors Apr 18 to Apr 25PeasPeas: sow outdoors Mar 21 to Apr 4CarrotCarrot: sow outdoors Apr 4 to Apr 18BeansBeans: sow outdoors Apr 18 to Apr 25Sweet cornSweet corn: sow outdoors Apr 18 to Apr 25Median last frost Apr 189 in 10 years May 6
Start indoorsHarden offSet outSow outdoorsMedian last frostLast freeze passed in 9 of 10 years
Every crop, counted from a median last frost of April 18
CropStart indoorsSet outSow outdoorsFrost class
TomatoFeb 28 to Mar 14Apr 25 to May 2Tender, very tender
PepperFeb 21 to Mar 7May 2 to May 9Tender, very tender
EggplantFeb 21 to Mar 7May 2 to May 9Tender, very tender
BasilMar 7 to Mar 21May 2 to May 9Tender
CeleryJan 24 to Feb 7Apr 18 to Apr 25Tender
CucumberMar 28 to Apr 4Apr 25 to May 2Apr 18 to Apr 25Tender
Summer squashApr 4 to Apr 11May 2 to May 9Apr 18 to Apr 25Tender
Winter squashApr 4 to Apr 11May 2 to May 9May 2 to May 9Tender, very tender
PumpkinApr 4 to Apr 11May 2 to May 9May 2 to May 9Tender, very tender
Melon (cantaloupe)Apr 4 to Apr 11May 2 to May 9Tender, very tender
WatermelonMar 28 to Apr 11May 2 to May 9Tender, very tender
Onion (from seed)Jan 10 to Jan 24Mar 21 to Mar 28Hardy
LeekJan 10 to Jan 24Mar 21 to Mar 28Hardy
ParsleyJan 17 to Jan 24Mar 28 to Apr 4Half-hardy
BroccoliFeb 7 to Feb 21Mar 21 to Apr 4Hardy
Brussels sproutsFeb 7 to Feb 21Mar 21 to Apr 4Hardy
CabbageFeb 7 to Feb 21Mar 21 to Mar 28Hardy
CauliflowerFeb 21 to Mar 7Apr 4 to Apr 11Half-hardy
KaleFeb 7 to Feb 21Mar 21 to Mar 28Hardy
LettuceFeb 14 to Feb 21Mar 21 to Mar 28Hardy
Swiss chardFeb 21 to Mar 7Apr 4 to Apr 11Mar 21 to Mar 28Half-hardy
SpinachJan 24 to Feb 7Mar 7 to Mar 28Mar 21 to Apr 4Hardy
PeasMar 21 to Apr 4Hardy
RadishMar 21 to Apr 4Hardy
CarrotApr 4 to Apr 18Half-hardy
BeetApr 4 to Apr 18Half-hardy
BeansApr 18 to Apr 25Tender
Sweet cornApr 18 to Apr 25Tender
Six square pots of dark compost seen from above, each holding a single seedling with two narrow seed leaves
Tomato seedlings at the seed leaf stage, one to a pot. The University of Minnesota Extension holds off on fertilizer until a seedling has several sets of true leaves, then feeds at quarter strength once a week. “Tomato Seedlings (49768696597)” by Amanda Slater from Coventry, West Midlands, UK, CC BY-SA 2.0
Extension guide

What Penn State Extension advises

Penn State Extension publishes the planting guide Pennsylvania gardeners work from, Cool-season vs. Warm-season Vegetables.

“Cool-season crops are the first ones to plant in the garden year. This can be anytime from several weeks to a couple of months before the last frost date.”
Penn State Extension, Cool-season vs. Warm-season Vegetables, quoted exactly.
“Starting eggplant indoors from seed at least 6 to 8 weeks before the last frost date is essential.”
Penn State Extension, on eggplant, quoted exactly.
“Sow seeds four to six weeks prior to your last average frost date in a loose starting mix.”
Penn State Extension, on melon, quoted exactly.
“Recommendations are to plant spinach about four to eight weeks before your average last frost date in the spring and six to eight weeks before the average first frost date in the fall.”
Penn State Extension, on spinach, quoted exactly.
“Sow seed ¼ inch deep outdoors in late spring to early summer after the risk of frost has passed, or start seeds indoors using a heat mat, 6 weeks before planting outside.”
Penn State Extension, on basil, quoted exactly.
A gardener kneeling beside a raised bed setting a young tomato plant into dark soil, an empty nursery pot beside her
Setting out a tomato in June at a community garden. Tender crops go out after the last frost, and after a week or two of hardening off outdoors. “Volunteer planting heirloom tomato (4704185147)”, Pacific Southwest Region 5, Public domain

Seed starting questions for Pennsylvania

Frost dates from NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal, by station (v1.0.1). Planting guidance from Penn State Extension, quoted exactly. Seed starting weeks from UNH Cooperative Extension. Compiled 2026-09-21.

First frost in PennsylvaniaThe other end of the season: when fall frost ends the tender crops.Soil temperatureBeans, corn and squash sown direct wait on warm soil as well as the last frost.Pennsylvania lawn care calendarSpring seeding, feeding and mowing dates on the same climate.Fall planting calendarGarlic, cool season crops and a second sowing window in the fall.Frost dates by ZIPFirst and last frost odds for any address.

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