When to plant in Somerville, NJ
USDA Zone 7aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Somerville, New Jersey — all computed from Somerville's nearest NOAA weather station.
Zone 7a means many perennials and even some tender shrubs overwinter in Somerville, while your frost dates still decide when annuals go out.
The average first fall frost in Somerville is now 6 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SOMERVILLE 4 NW · 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 Somerville’s own odds, recorded at SOMERVILLE 4 NW.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 24 | May 10 | Apr 27 | Sep 28 | Oct 9 | Oct 24 |
| 32°F | May 14 | Apr 30 | Apr 15 | Oct 5 | Oct 20 | Nov 3 |
| 28°F | May 1 | Apr 15 | Apr 1 | Oct 15 | Oct 31 | Nov 12 |
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 Somerville, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 18 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.
Somerville planting FAQ
When is the last spring frost in Somerville, NJ?
Plan for the last spring frost in Somerville around April 30 (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 Somerville, NJ?
Expect Somerville's first fall frost near October 20 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Somerville in?
Somerville is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Somerville?
There are roughly 173 frost-free days in Somerville (a moderate growing season), running from the average last frost around April 30 to the first fall frost near October 20.
When should I plant tomatoes in Somerville?
In Somerville, start tomato seeds indoors around March 5–March 19, then transplant seedlings outdoors around May 7 once the danger of frost has passed.
Never miss a window in Somerville
An email when it’s time to start seeds, transplant, and sow — timed to Somerville’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Manville · 4 km
- Martinsville · 5 km
- Bradley Gardens · 5 km
- Bound Brook · 6 km
- Hillsborough · 8 km
- Middlesex · 9 km
- The Hills · 9 km
- Blackwells Mills · 10 km
Frost dates recorded at SOMERVILLE 4 NW, 6 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 Somerville, NJ — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00288194. Retrieved from https://blissgarden.com/new-jersey/somerville.