Acton, MA planting zone & frost dates

Acton is in USDA hardiness zone 6b. The last spring frost usually comes around May 2 and the first fall frost around October 6, for a growing season of about 156 days.

USDA hardiness zone6bavg. extreme winter low -5°F to 0°F

Average last spring frostMay 290% chance of no frost after May 16

Average first fall frostOctober 610% chance of frost by September 25

Growing season156 daysfrost-free days in an average year

Planting calendar for Acton

Dates are counted from the average last spring frost (May 2) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.

Crop	When
Tomatoes	Start seeds indoors: Mar 7 – Mar 21 Transplant outdoors: May 9 – May 16
Peppers	Start seeds indoors: Feb 21 – Mar 7 Transplant outdoors: May 16 – May 23
Eggplant	Start seeds indoors: Feb 21 – Mar 7 Transplant outdoors: May 16 – May 23
Broccoli	Start seeds indoors: Feb 21 – Mar 7 Transplant outdoors: Apr 4 – Apr 18
Cabbage	Start seeds indoors: Feb 21 – Mar 7 Transplant outdoors: Apr 4 – Apr 18
Onions (sets)	Plant outdoors: Apr 4 – Apr 18
Peas	Sow outdoors: Mar 21 – Apr 4
Spinach	Sow outdoors: Mar 21 – Apr 4
Lettuce	Sow outdoors: Apr 4 – Apr 18
Carrots	Sow outdoors: Apr 4 – Apr 18
Potatoes	Plant outdoors: Apr 4 – Apr 18
Beans	Sow outdoors: May 9 – May 16
Sweet corn	Sow outdoors: May 9 – May 16
Cucumbers	Sow outdoors: May 9 – May 16
Squash & zucchini	Sow outdoors: May 9 – May 16
Basil	Start seeds indoors: Mar 21 – Apr 4 Transplant outdoors: May 9 – May 16

Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 11 (8 weeks before the average first fall frost on Oct 6).

Useful for zone 6b gardens

Seed starting kit with dome — to start seeds indoors before the last frost
LED grow light for seedlings — stops leggy seedlings
Frost cloth / plant covers — for late spring and early fall frosts
Soil thermometer — warm-season crops need soil above 60°F
Cold frame / mini greenhouse — adds weeks to a short season

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Frost risk in detail

	90% chance	50% chance	10% chance
Last 32°F frost in spring is after	Apr 22	May 2	May 16
First 32°F frost in fall is before	Oct 22	Oct 6	Sep 25

How to read it: in spring there is a 10% chance of a frost after May 16, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 25. A hard freeze (28°F) usually ends around April 21.

Hardiness zone by ZIP code in Acton

01720 zone 6b

Nearby cities

Maynard zone 6b, last frost May 2
Concord zone 6b, last frost Apr 28
Westford zone 6a, last frost Apr 30
Sudbury zone 6b, last frost May 2
Chelmsford zone 6b, last frost Apr 30
Wayland zone 6b, last frost Apr 26
Bedford zone 6b, last frost Apr 27
Hudson zone 6b, last frost May 2

All cities in Massachusetts → · Other zone 6b cities →

Questions

What growing zone is Acton, MA?

Acton is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map.

When is the last frost in Acton?

The average last spring frost (32°F) in Acton is May 2. There is still a 10% chance of frost until May 16.

When can I plant tomatoes in Acton?

Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 9 – May 16. Start seeds indoors 6–8 weeks before the last frost.

Frost dates: NOAA U.S. Climate Normals 1991–2020, station Maynard 2, MA (USC00194580), 6.3 km (3.9 mi) from the city center, elevation 62 m, based on 19 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.