When to plant in Marlborough, MA
USDA Zone 6bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Marlborough, Massachusetts — all computed from Marlborough's nearest NOAA weather station.
Zone 6b means Marlborough sees real winter cold, but a good range of perennials survive; the frost dates above govern when annual vegetables go out.
Frost probability
MAYNARD 2 · 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 Marlborough’s own odds, recorded at MAYNARD 2.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 27 | May 13 | Apr 30 | Sep 14 | Sep 27 | Oct 8 |
| 32°F | May 16 | May 2 | Apr 22 | Sep 25 | Oct 6 | Oct 22 |
| 28°F | May 5 | Apr 21 | Apr 8 | Oct 2 | Oct 18 | Nov 3 |
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 Marlborough, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 25 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.
Marlborough planting FAQ
When is the last spring frost in Marlborough, MA?
Plan for the last spring frost in Marlborough around May 2 (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 Marlborough, MA?
Expect Marlborough's first fall frost near October 6 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Marlborough in?
Marlborough 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 Marlborough?
There are roughly 157 frost-free days in Marlborough (a moderate growing season), running from the average last frost around May 2 to the first fall frost near October 6.
When should I plant tomatoes in Marlborough?
In Marlborough, start tomato seeds indoors around March 7–March 21, then transplant seedlings outdoors around May 9 once the danger of frost has passed.
Never miss a window in Marlborough
An email when it’s time to start seeds, transplant, and sow — timed to Marlborough’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at MAYNARD 2, 12 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 Marlborough, MA — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00194580. Retrieved from https://blissgarden.com/massachusetts/marlborough.