When to plant in Waltham, MA
USDA Zone 6bEverything below — frost dates, hardiness zone, and what to plant when in Waltham, Massachusetts — is derived from the closest NOAA station with complete climate normals.
In zone 6b, Waltham gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average last spring frost in Waltham is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
BEDFORD HANSCOM FLD · 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 Waltham’s own odds, recorded at BEDFORD HANSCOM FLD.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 23 | May 10 | Apr 28 | Sep 17 | Oct 1 | Oct 13 |
| 32°F | May 12 | Apr 28 | Apr 13 | Sep 28 | Oct 10 | Oct 28 |
| 28°F | Apr 29 | Apr 12 | Apr 1 | Oct 7 | Oct 25 | Nov 8 |
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 Waltham, 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.
Waltham planting FAQ
When is the last spring frost in Waltham, MA?
Waltham's average last spring frost falls near April 28 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Waltham, MA?
Expect Waltham's first fall frost near October 10 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Waltham in?
Waltham 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 Waltham?
Waltham has about 165 frost-free days — a moderate growing season — between the average last spring frost (April 28) and first fall frost (October 10).
When should I plant tomatoes in Waltham?
For Waltham, sow tomatoes indoors about March 3–March 17 and move the seedlings out around May 5, after the last spring frost.
Never miss a window in Waltham
An email when it’s time to start seeds, transplant, and sow — timed to Waltham’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reachFrost dates recorded at BEDFORD HANSCOM FLD, 10 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 Waltham, MA — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00014702. Retrieved from https://blissgarden.com/massachusetts/waltham.