What does USDA hardiness zone 5a mean in Vermont?

Zone 5a means an average annual extreme minimum winter temperature of −20 to −15 °F — the standard USDA measure of which perennials survive winter. 24 locations in Vermont fall in this zone. It does not set planting dates; see the frost calendar below for that.

Where in Vermont's zone 5a is the growing season longest?

South Burlington runs the longest season on this page at about 169 days; East Barre is shortest at about 119 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.

When should I plant tomatoes in Vermont's zone 5a?

Using Killington's frost dates (this page's median-season location): start seeds indoors about Mar 18 – Apr 1, then transplant outside about May 20 – May 27. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.

Does every location in Vermont's zone 5a have the same frost dates?

No — they do not all share a weather station, so frost dates vary by a week or more across the 24 locations listed (see the table above for each location's own dates).

USDA zone 5a in Vermont

−20 to −15 °F avg. annual extreme minimum · 24 locations in this group · NOAA 1991–2020 normals

USDA plant hardiness zone 5a covers 24 locations across Vermont (average annual extreme minimum −20 to −15 °F): Arlington, VT, Bristol, VT, Cambridge, VT, Chelsea, VT, Chelsea, VT, East Barre, VT, and 18 more. Average last spring frost across this group ranges April 29 (South Burlington) to May 25 (East Barre), and growing seasons run 119–169 days (East Barre to South Burlington) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Vermont location's own frost dates; the printable planting calendar uses Killington, this group's median-season location.

USDA zone: 5a−20 to −15 °F
Last frost range: Apr 29–May 25avg, 32°F
First frost range: Sep 22–Oct 17avg, 32°F
Growing season range: 119–169days

Locations in this group

Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.

Own frost dates per location.
Location	Also covers	Nearest station	Last frost	First frost	Season (days)
Arlington	Manchester	Sunderland 2	May 13	Sep 29	137
Bristol	Waitsfield, Hanksville	S Lincoln	May 21	Sep 25	124
Cambridge	Jeffersonville, Stowe, Underhill Flats, Underhill Center	Mt Mansfield	May 23	Sep 30	130
Chelsea	—	Chelsea 2 Nw	May 9	Oct 1	143
Chelsea	—	Corinth	May 14	Sep 29	136
East Barre	Groton, Plainfield, Worcester	Plainfield	May 25	Sep 22	119
Essex Junction	Fairfax, Westford	Essex Junction 1 N	May 2	Oct 11	160
Fairlee	—	Wentworth	May 12	Oct 6	146
Killington *	Quechee, Woodstock, South Royalton, Hartland, West Woodstock	Woodstock	May 13	Oct 1	141
Killington	Randolph, South Lincoln, Bethel, Chelsea, Rochester, Chittenden	Rochester	May 13	Oct 2	141
Lowell	St. Albans, Bakersfield, Highgate Center	Enosburg Falls	May 14	Oct 1	139
Ludlow	Windsor, Jamaica, South Londonderry, Londonderry, Weston, Grafton	Springfield Hartness Ap	May 13	Oct 3	143
Manchester Center	East Dorset, Dorset, Jamaica	Peru	May 16	Oct 2	140
Middlebury	Ticonderoga, Benson, Mineville, Brandon, New Haven, Vergennes, +3 more	Cornwall	May 5	Oct 3	151
Montpelier	Williamstown, East Barre, Northfield, Websterville, Graniteville, Waterbury, +1 more	Barre Montpelier Ap	May 16	Sep 29	136
Newbury	North Haverhill, Lisbon, Wells River, Woodsville, North Woodstock, Bradford, +1 more	Benton 5 Sw	May 15	Sep 28	133
North Hyde Park	Johnson, Waterbury Center	Morrisville Stowe State Ap	May 20	Sep 28	129
Rutland	Killington, Proctor, West Rutland, Pittsford, Wallingford, North Clarendon, +3 more	Rutland	May 15	Sep 27	132
South Burlington	Willsboro, Winooski, Richmond, Hinesburg, St. George, West Charlotte, +2 more	Burlington Intl Ap	Apr 29	Oct 15	169
Stratton Mountain	South Shaftsbury, Chimney Hill, Wardsboro	Bennington Morse St Ap	May 11	Oct 2	143
Swanton	—	St Albans Radio	May 1	Oct 12	161
Troy	—	Jay Peak	May 14	Oct 1	138
Vergennes	—	Vergennes	Apr 30	Oct 17	168
Worcester	—	Worcester 2 W	May 4	Oct 5	153

* Killington is this group's median-season location — the calendar below is computed from its data.

Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.

Planting calendar (Killington, representative)

Computed from Killington's average frost dates — the median-season location in this Vermontzone 5a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).

Crop

JanFebMarAprMayJunJulAugSepOctNovDec

Tomato

Pepper

Cucumber

Summer squash / zucchini

Start indoors
Plant out
Fall sowing
First harvest

Planting windows for Killington (Vermont, zone 5a), this group's representative location.
Crop	Frost tolerance	Start indoors	Plant out	First harvest	Fall planting	Season fit
Tomato	Tender	Mar 18 – Apr 1	May 20 – May 27	Jul 19 – Aug 8	—	matures comfortably
Pepper	Very tender	Mar 4 – Mar 18	May 27 – Jun 3	Jul 26 – Aug 25	—	matures comfortably
Cucumber	Tender	Apr 15 – Apr 22	May 20 – May 27	Jul 9 – Jul 29	—	matures comfortably
Summer squash / zucchini	Tender	—	May 20 – May 27	Jul 4 – Jul 19	—	matures comfortably
Bush bean	Tender	—	May 20 – May 27	Jul 9 – Jul 19	Aug 2 – Aug 12	matures comfortably
Sweet corn	Tender	—	May 13 – May 27	Jul 12 – Aug 11	—	matures comfortably
Basil	Very tender	Apr 1 – Apr 15	May 20 – May 27	Jun 19 – Jul 4	—	matures comfortably
Lettuce	Half-hardy	Apr 1 – Apr 15	Apr 15 – Apr 29	May 30 – Jun 14	Jul 19 – Aug 3	matures comfortably
Pea	Hardy	—	Apr 1 – Apr 15	May 26 – Jun 10	Jul 9 – Jul 24	matures comfortably
Spinach	Hardy	—	Apr 1 – Apr 15	May 11 – May 21	Jul 29 – Aug 8	matures comfortably
Carrot	Half-hardy	—	Apr 22 – Apr 29	Jun 21 – Jul 11	Jun 29 – Jul 19	matures comfortably
Broccoli	Half-hardy	Mar 18 – Apr 1	Apr 15 – Apr 29	Jun 9 – Jun 29	Jul 4 – Jul 24	matures comfortably

Which crops fit this growing season

Using Killington's own 141-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.

Frost & freeze dates (Killington)

From NOAA's 1991–2020 Climate Normals at station USC00439984. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.

Freeze probabilities by temperature threshold (MM/DD, NOAA 1991–2020), Killington.
Threshold	Last spring — avg	Last spring — 90%-safe	First fall — avg	First fall — 90%-safe	Season (days)
36°F	May 24	Jun 6	Sep 23	Oct 3	121
32°F (freeze)	May 13	May 27	Oct 1	Oct 15	141
28°F	Apr 30	May 15	Oct 12	Oct 31	164
24°F	Apr 16	Apr 29	Oct 25	Nov 9	191

Growing degree days

Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 24 locations is 2,009; Killington's own reading is shown below.

Annual growing degree days for Killington (°F·days, NOAA 1991–2020).
Model	°F·days	Used for
Base 50°F (warm-season)	2,230	standard warm-season base (tomato, corn, beans)
Base 40°F (cool-season)	4,088	cool-season crops (brassicas, greens)

Hardiness zone 5a in Vermont

Zone 5a means an average annual extreme minimum winter temperature of about −20 to −15 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Vermont spans 4 hardiness zones in this dataset — see all Vermont locations for the full range, including zones4a, 4b, 5b.

Explore zone 5a in other states at zone 5a, or see all USDA hardiness zones.

Frequently asked questions

What does USDA hardiness zone 5a mean in Vermont?: Zone 5a means an average annual extreme minimum winter temperature of −20 to −15 °F — the standard USDA measure of which perennials survive winter. 24 locations in Vermont fall in this zone. It does not set planting dates; see the frost calendar below for that.
Where in Vermont's zone 5a is the growing season longest?: South Burlington runs the longest season on this page at about 169 days; East Barre is shortest at about 119 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
When should I plant tomatoes in Vermont's zone 5a?: Using Killington's frost dates (this page's median-season location): start seeds indoors about Mar 18 – Apr 1, then transplant outside about May 20 – May 27. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
Does every location in Vermont's zone 5a have the same frost dates?: No — they do not all share a weather station, so frost dates vary by a week or more across the 24 locations listed (see the table above for each location's own dates).

Sources & method

Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.