Worcester, Massachusetts: planting zone & frost dates
Worcester is in USDA plant hardiness zone 6a, where the average coldest winter night reaches -10 to -5°F (-23.3 to -20.6°C). The typical last spring frost is around May 6 and the first fall frost around Oct 4.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 13 | Sep 28 |
| Typical planning date (30% risk) | May 6 | Oct 4 |
| Median (50%) | May 1 | Oct 10 |
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 BUFFUMVILLE LAKE, MA (USC00190998), 11.7 mi (18.9 km) from the city center and 26 ft higher than the city center (+8 m). Record used for the 1991–2020 normals: 25 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Worcester
Worcester spans more than one half-zone. Share of the city's land area by zone (via its 9 ZIP codes): 6a (59%), 6b (41%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Worcester
Dates are counted from the 30%-risk frost dates above (last frost May 6, first frost Oct 4). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 11 – Mar 25 | May 13 – May 27 | — | — |
| Pepper | Feb 25 – Mar 11 | May 20 – Jun 3 | — | — |
| Lettuce | Mar 25 – Apr 8 | Apr 22 – May 13 | Apr 8 – May 20 | Jul 26 – Aug 23 |
| Green Beans | — | — | May 13 – Jun 17 | Jul 12 – Jul 26 |
| Sweet Corn | — | — | May 13 – Jun 10 | — |
| Zucchini & Summer Squash | Apr 8 – Apr 15 | May 13 – May 27 | May 13 – Jun 3 | Jul 12 – Jul 26 |
| Cucumber | Apr 8 – Apr 15 | May 20 – May 27 | May 13 – Jun 3 | Jul 12 – Jul 26 |
| Carrot | — | — | Apr 15 – May 20 | Jul 12 – Jul 26 |
| Onion | Feb 11 – Feb 25 | Apr 8 – Apr 22 | — | — |
| Potato | — | Apr 8 – Apr 29 | — | — |
| Basil | Mar 25 – Apr 8 | May 20 – Jun 3 | May 20 – Jun 10 | — |
| Spinach | — | — | Mar 25 – Apr 22 | Aug 9 – Sep 6 |
| Kale | Mar 11 – Mar 25 | Apr 8 – Apr 29 | Apr 8 – Apr 29 | Jul 26 – Aug 23 |
| Broccoli | Mar 11 – Mar 25 | Apr 22 – May 13 | — | Jul 12 – Jul 26 |
| Peas | — | — | Mar 25 – Apr 15 | Jul 26 – Aug 9 |
| Eggplant | Feb 25 – Mar 11 | May 20 – Jun 3 | — | — |
| Cabbage | Mar 11 – Mar 25 | Apr 8 – Apr 22 | — | Jul 12 – Jul 26 |
| Radish | — | — | Apr 1 – May 20 | Aug 23 – Sep 20 |
| Strawberry | — | Apr 8 – Apr 29 | — | — |
| Beets | — | — | Apr 15 – May 27 | Jul 26 – Aug 9 |
Nearby cities in Massachusetts
- Newton — zone 6b, last frost Apr 24, first frost Oct 16
- Lowell — zone 6b, last frost May 3, first frost Oct 5
- Cambridge — zone 6b, last frost Apr 8, first frost Nov 3
- Somerville — zone 7a, last frost Apr 8, first frost Nov 3
- Springfield — zone 6a, last frost May 9, first frost Oct 3
- Lawrence — zone 6b, last frost Apr 19, first frost Oct 22
More: all Massachusetts cities · other zone 6a cities: Chicago, IL, Denver, CO, Milwaukee, WI, Colorado Springs, CO, Omaha, NE, Aurora, CO, Lincoln, NE, Fort Wayne, IN
Worcester gardening questions
When is the last frost in Worcester, MA?
Plan around May 6. At NOAA's Buffumville Lake, MA station, 11.7 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 May 1, and after May 13 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 19. The last frost is fairly predictable here: only 22 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Worcester, MA?
Start seeds indoors Mar 11 – Mar 25 and set transplants outside May 13 – May 27, once nights stay above 50°F and the soil is near 60°F. That leaves 151 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 Worcester?
About 162 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 143 days, and in 1 year in 10 it runs 180 days or more. In fall there is a 10% chance of frost by Sep 28 and a 30% chance by Oct 4. That ranks 12th longest of 13 Massachusetts cities on this site.
When should I plant a fall garden in Worcester?
Count back from the first fall frost (Oct 4): transplant broccoli Jul 12 – Jul 26; sow kale Jul 26 – Aug 23; sow lettuce Jul 26 – Aug 23; sow radishes Aug 23 – Sep 20. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 22. How the math works: succession and fall planting.
Did Worcester's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Worcester is zone 6a 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.
Is all of Worcester in zone 6a?
No. Zone 6a covers about 59% of the city's land; the rest is in 6b (41%), measured across the city's 9 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.