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Seed Starting Calendar for Connecticut

Median last frost from Apr 14 to May 8 across Connecticut

NOAA stations
22
Median last frost, Hartford
Apr 17
Passed in 9 of 10 years
May 1
Last frost

Last spring frost dates in Connecticut

Bridgeport on Long Island Sound reaches its median last frost around Apr 5, while Norfolk in the Litchfield Hills waits until about May 3, four weeks later for the same tomato.

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
BridgeportBridgeport Sikorsky Memorial Airport, USW000947025 ftMar 25Apr 5Apr 17Nov 6
Groton New London AirportGroton New London Airport, USW0001470710 ftApr 3Apr 16Apr 30Oct 28
HartfordHartford Brainard Field, USW0001475219 ftApr 1Apr 17May 1Oct 26
W Thompson LakeW Thompson Lake, USC00069388360 ftApr 20May 1May 17Oct 9
NorfolkNorfolk 2 SW, USC000654451,340 ftApr 21May 3May 17Oct 11
Crop chart

When to start seeds in Connecticut, spring 2027

Counted back from the median last frost at Hartford, April 17. Pick another station to redraw the chart for it.

Seed starting calendar for Hartford, Connecticut, spring 2027JanFebMarAprMayOnion (from seed)Onion (from seed): start indoors Jan 9 to Jan 23Onion (from seed): harden off Mar 6 to Mar 20Onion (from seed): set out Mar 20 to Mar 27PepperPepper: start indoors Feb 20 to Mar 6Pepper: harden off Apr 17 to May 1Pepper: set out May 1 to May 8EggplantEggplant: start indoors Feb 20 to Mar 6Eggplant: harden off Apr 17 to May 1Eggplant: set out May 1 to May 8TomatoTomato: start indoors Feb 27 to Mar 13Tomato: harden off Apr 10 to Apr 24Tomato: set out Apr 24 to May 1BroccoliBroccoli: start indoors Feb 6 to Feb 20Broccoli: harden off Mar 6 to Mar 20Broccoli: set out Mar 20 to Apr 3CabbageCabbage: start indoors Feb 6 to Feb 20Cabbage: harden off Mar 6 to Mar 20Cabbage: set out Mar 20 to Mar 27LettuceLettuce: start indoors Feb 13 to Feb 20Lettuce: harden off Mar 6 to Mar 20Lettuce: set out Mar 20 to Mar 27BasilBasil: start indoors Mar 6 to Mar 20Basil: harden off Apr 17 to May 1Basil: set out May 1 to May 8CucumberCucumber: start indoors Mar 27 to Apr 3Cucumber: harden off Apr 10 to Apr 24Cucumber: set out Apr 24 to May 1Cucumber: sow outdoors Apr 17 to Apr 24Summer squashSummer squash: start indoors Apr 3 to Apr 10Summer squash: harden off Apr 17 to May 1Summer squash: set out May 1 to May 8Summer squash: sow outdoors Apr 17 to Apr 24PeasPeas: sow outdoors Mar 20 to Apr 3CarrotCarrot: sow outdoors Apr 3 to Apr 17BeansBeans: sow outdoors Apr 17 to Apr 24Sweet cornSweet corn: sow outdoors Apr 17 to Apr 24Median last frost Apr 179 in 10 years May 1
Start indoorsHarden offSet outSow outdoorsMedian last frostLast freeze passed in 9 of 10 years
Every crop, counted from a median last frost of April 17
CropStart indoorsSet outSow outdoorsFrost class
TomatoFeb 27 to Mar 13Apr 24 to May 1Tender, very tender
PepperFeb 20 to Mar 6May 1 to May 8Tender, very tender
EggplantFeb 20 to Mar 6May 1 to May 8Tender, very tender
BasilMar 6 to Mar 20May 1 to May 8Tender
CeleryJan 23 to Feb 6Apr 17 to Apr 24Tender
CucumberMar 27 to Apr 3Apr 24 to May 1Apr 17 to Apr 24Tender
Summer squashApr 3 to Apr 10May 1 to May 8Apr 17 to Apr 24Tender
Winter squashApr 3 to Apr 10May 1 to May 8May 1 to May 8Tender, very tender
PumpkinApr 3 to Apr 10May 1 to May 8May 1 to May 8Tender, very tender
Melon (cantaloupe)Apr 3 to Apr 10May 1 to May 8Tender, very tender
WatermelonMar 27 to Apr 10May 1 to May 8Tender, very tender
Onion (from seed)Jan 9 to Jan 23Mar 20 to Mar 27Hardy
LeekJan 9 to Jan 23Mar 20 to Mar 27Hardy
ParsleyJan 16 to Jan 23Mar 27 to Apr 3Half-hardy
BroccoliFeb 6 to Feb 20Mar 20 to Apr 3Hardy
Brussels sproutsFeb 6 to Feb 20Mar 20 to Apr 3Hardy
CabbageFeb 6 to Feb 20Mar 20 to Mar 27Hardy
CauliflowerFeb 20 to Mar 6Apr 3 to Apr 10Half-hardy
KaleFeb 6 to Feb 20Mar 20 to Mar 27Hardy
LettuceFeb 13 to Feb 20Mar 20 to Mar 27Hardy
Swiss chardFeb 20 to Mar 6Apr 3 to Apr 10Mar 20 to Mar 27Half-hardy
SpinachJan 23 to Feb 6Mar 6 to Mar 27Mar 20 to Apr 3Hardy
PeasMar 20 to Apr 3Hardy
RadishMar 20 to Apr 3Hardy
CarrotApr 3 to Apr 17Half-hardy
BeetApr 3 to Apr 17Half-hardy
BeansApr 17 to Apr 24Tender
Sweet cornApr 17 to Apr 24Tender
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 UConn Extension / UConn Home and Garden Education Center advises

UConn Extension / UConn Home and Garden Education Center publishes the planting guide Connecticut gardeners work from, Vegetable Garden: Basics and Plant Selections.

“Seed or transplant info will say “Plant after all danger of frost has past”. This varies from year to year. May 15th is only an average.”
UConn Extension / UConn Home and Garden Education Center, Vegetable Garden: Basics and Plant Selections, quoted exactly.
“Seedlings that have a 4-6 week headstart indoors can extend that period.”
UConn Extension / UConn Home and Garden Education Center, Seed Starting, UConn Home and Garden Education Center, quoted exactly.
“Seeds must be started indoors 6 weeks before the last frost date (average of mid-May in CT) or you can buy plants to put in the ground in early June.”
UConn Extension / UConn Home and Garden Education Center, on tomato, quoted exactly.
“Seeds of vegetables, such as tomatoes, peppers, eggplants, and herbs that require 10-12 weeks of growth before transplanting can be started indoors this month.”
UConn Extension / UConn Home and Garden Education Center, on pepper, quoted exactly.
“Vegetable Gardening Weather permitting, direct sow​ ​peas, ​carrots, ​radishes, ​lettuces, ​and​ ​spinach every two weeks through mid-May for staggered harvests.”
UConn Extension / UConn Home and Garden Education Center, on peas, quoted exactly.
“Seed packet will say “Plant as early as soil can be worked”.”
UConn Extension / UConn Home and Garden Education Center, on lettuce, 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 Connecticut

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

First frost in ConnecticutThe 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.Connecticut 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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