US Grow Zones

South Burlington, Vermont: planting zone & frost dates

Last updated · Sources: PRISM/OSU 2023 ZIP zone listings; NOAA NCEI 1991–2020 Climate Normals (station USW00014742); U.S. Census Bureau — see methodology

South Burlington is in USDA plant hardiness zone 5a, where the average coldest winter night reaches -20 to -15°F (-28.9 to -26.1°C). The typical last spring frost is around May 3 and the first fall frost around Oct 9.

Hardiness zone5A-20 to -15°F
Last spring frostMay 330% chance of frost after
First fall frostOct 930% chance of frost before
Growing season169 daysmedian frost-free days

Frost dates

ProbabilityLast spring frost (32°F)First fall frost (32°F)
Safer (10% risk)May 11Oct 2
Typical planning date (30% risk)May 3Oct 9
Median (50%)Apr 29Oct 15

How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.

Frost data comes from NOAA station BURLINGTON INTL AP, VT (USW00014742), 2.7 mi (4.4 km) from the city center and 52 ft lower than the city center (-16 m). Record used for the 1991–2020 normals: 29 years.

Frost probability in spring and fall, South Burlington, VTChance of a 32°F frost in South Burlington, VT, NOAA 1991–2020. Spring: the chance of another frost falls from 90% on Apr 17 to 10% on May 11. Fall: the chance that the first frost has arrived rises from 10% on Oct 2 to 90% on Nov 1.0%50%100%Spring: later frostApr 1Apr 15May 1May 1530%: May 3Fall: frost arrivedOct 1Oct 15Nov 1Nov 1530%: Oct 932°F frost28°F hard freezeplanning date
Shaded areas show the chance of a 32°F frost: falling through spring, rising through fall. The dashed line is the 28°F hard-freeze curve. Data: NOAA 1991–2020 Normals, station USW00014742.
Frost-free growing season in South Burlington, VT1 in 10 risk: May 11 to Oct 2 (144 days); 3 in 10 risk: May 3 to Oct 9 (159 days); Median (50%): Apr 29 to Oct 15 (169 days); No 28°F freeze: Apr 18 to Oct 28 (193 days). In 9 of 10 years the 32°F-free season is at least 149 days.Frost-free days, spring to fallJFMAMJJASOND1 in 10 risk144 days3 in 10 risk159 daysMedian (50%)169 daysNo 28°F freeze193 days
Frost-free window at three risk levels, plus the window between 28°F hard freezes. Read about what the probabilities mean.

Why your yard may differ from the station: microclimates.

Hardiness zone across South Burlington

All 1 ZIP code covering South Burlington is in zone 5a.

ZIP codes in South Burlington and their zones
ZIPZoneShare of city land
054035a99.4%

Vegetable planting calendar for South Burlington

Dates are counted from the 30%-risk frost dates above (last frost May 3, first frost Oct 9). Shift a week later in cold spots or low-lying ground.

CropStart indoorsTransplant / plant outDirect sowFall crop sow/plant
TomatoMar 8 – Mar 22May 10 – May 24——
PepperFeb 22 – Mar 8May 17 – May 31——
LettuceMar 22 – Apr 5Apr 19 – May 10Apr 5 – May 17Jul 31 – Aug 28
Green Beans——May 10 – Jun 14Jul 17 – Jul 31
Sweet Corn——May 10 – Jun 7—
Zucchini & Summer SquashApr 5 – Apr 12May 10 – May 24May 10 – May 31Jul 17 – Jul 31
CucumberApr 5 – Apr 12May 17 – May 24May 10 – May 31Jul 17 – Jul 31
Carrot——Apr 12 – May 17Jul 17 – Jul 31
OnionFeb 8 – Feb 22Apr 5 – Apr 19——
Potato—Apr 5 – Apr 26——
BasilMar 22 – Apr 5May 17 – May 31May 17 – Jun 7—
Spinach——Mar 22 – Apr 19Aug 14 – Sep 11
KaleMar 8 – Mar 22Apr 5 – Apr 26Apr 5 – Apr 26Jul 31 – Aug 28
BroccoliMar 8 – Mar 22Apr 19 – May 10—Jul 17 – Jul 31
Peas——Mar 22 – Apr 12Jul 31 – Aug 14
EggplantFeb 22 – Mar 8May 17 – May 31——
CabbageMar 8 – Mar 22Apr 5 – Apr 19—Jul 17 – Jul 31
Radish——Mar 29 – May 17Aug 28 – Sep 25
Strawberry—Apr 5 – Apr 26——
Beets——Apr 12 – May 24Jul 31 – Aug 14

Nearby cities in Vermont

More: all Vermont cities · other zone 5a cities: Minneapolis, MN, St. Paul, MN, Anchorage, AK, Sioux Falls, SD, Cedar Rapids, IA, Billings, MT, Bloomington, MN, Sioux City, IA

South Burlington gardening questions

When is the last frost in South Burlington, VT?

Plan around May 3. At NOAA's Burlington Int'l Airport, VT station, 2.7 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 29, and after May 11 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 18. The last frost is fairly predictable here: only 24 days separate the 90% and 10% dates (median for cities on this site: 36 days).

When should I plant tomatoes in South Burlington, VT?

Start seeds indoors Mar 8 – Mar 22 and set transplants outside May 10 – May 24, once nights stay above 50°F and the soil is near 60°F. That leaves 159 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.

How long is the growing season in South Burlington?

About 169 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 149 days, and in 1 year in 10 it runs 187 days or more. In fall there is a 10% chance of frost by Oct 2 and a 30% chance by Oct 9.

When should I plant a fall garden in South Burlington?

Count back from the first fall frost (Oct 9): transplant broccoli Jul 17 – Jul 31; sow kale Jul 31 – Aug 28; sow lettuce Jul 31 – Aug 28; sow radishes Aug 28 – Sep 25. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 28. How the math works: succession and fall planting.

Did South Burlington's hardiness zone change on the 2023 map?

No. Going by the zone that covers most of the city's land, South Burlington is zone 5a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.