When to plant in Hillsborough, NJ
USDA Zone 7aEverything below — frost dates, hardiness zone, and what to plant when in Hillsborough, New Jersey — is derived from the closest NOAA station with complete climate normals.
Zone 7a means many perennials and even some tender shrubs overwinter in Hillsborough, while your frost dates still decide when annuals go out.
The average first fall frost in Hillsborough 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 Hillsborough’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 Hillsborough, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 13 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.
Hillsborough planting FAQ
When is the last spring frost in Hillsborough, NJ?
Hillsborough's average last spring frost falls near April 30 — 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 Hillsborough, NJ?
The first fall frost in Hillsborough typically arrives around October 20 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Hillsborough in?
Hillsborough 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 Hillsborough?
There are roughly 173 frost-free days in Hillsborough (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 Hillsborough?
In Hillsborough, 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 Hillsborough
An email when it’s time to start seeds, transplant, and sow — timed to Hillsborough’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Blackwells Mills · 6 km
- Manville · 7 km
- Bradley Gardens · 7 km
- Somerville · 8 km
- Franklin Park · 12 km
- Bound Brook · 12 km
- Martinsville · 12 km
- Somerset · 13 km
Frost dates recorded at SOMERVILLE 4 NW, 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 Hillsborough, NJ — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00288194. Retrieved from https://blissgarden.com/new-jersey/hillsborough.