When to plant in Watertown, MA
USDA Zone 6bEverything below — frost dates, hardiness zone, and what to plant when in Watertown, Massachusetts — is derived from the closest NOAA station with complete climate normals.
In zone 6b, Watertown gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in Watertown is now 7 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
JAMAICA PLAIN · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Watertown’s own odds, recorded at JAMAICA PLAIN.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 16 | May 2 | Apr 20 | Sep 30 | Oct 10 | Oct 25 |
| 32°F | May 3 | Apr 19 | Apr 6 | Oct 8 | Oct 23 | Nov 5 |
| 28°F | Apr 21 | Apr 5 | Mar 25 | Oct 19 | Nov 3 | Nov 19 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Watertown, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 14 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Watertown planting FAQ
When is the last spring frost in Watertown, MA?
Plan for the last spring frost in Watertown around April 19 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Watertown, MA?
Expect Watertown's first fall frost near October 23 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Watertown in?
Watertown is in USDA hardiness zone 6b. In zone 6b, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Watertown?
Watertown has about 187 frost-free days — a moderate growing season — between the average last spring frost (April 19) and first fall frost (October 23).
When should I plant tomatoes in Watertown?
For Watertown, sow tomatoes indoors about February 22–March 8 and move the seedlings out around April 26, after the last spring frost.
Never miss a window in Watertown
An email when it’s time to start seeds, transplant, and sow — timed to Watertown’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at JAMAICA PLAIN, 9 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Watertown, MA — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00193890. Retrieved from https://blissgarden.com/massachusetts/watertown.