When to plant in Williamstown, NJ
USDA Zone 7aEverything below — frost dates, hardiness zone, and what to plant when in Williamstown, 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 Williamstown, while your frost dates still decide when annuals go out.
The average last spring frost in Williamstown is now 9 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
GLASSBORO 2 NE · 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 Williamstown’s own odds, recorded at GLASSBORO 2 NE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 4 | Apr 22 | Apr 8 | Oct 9 | Oct 21 | Nov 2 |
| 32°F | Apr 22 | Apr 8 | Mar 27 | Oct 18 | Nov 1 | Nov 15 |
| 28°F | Apr 9 | Mar 27 | Mar 12 | Oct 30 | Nov 11 | Nov 29 |
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 Williamstown, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 21 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.
Williamstown planting FAQ
When is the last spring frost in Williamstown, NJ?
Plan for the last spring frost in Williamstown around April 8 (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 Williamstown, NJ?
The first fall frost in Williamstown typically arrives around November 1 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Williamstown in?
Williamstown 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 Williamstown?
There are roughly 207 frost-free days in Williamstown (a moderate growing season), running from the average last frost around April 8 to the first fall frost near November 1.
When should I plant tomatoes in Williamstown?
In Williamstown, start tomato seeds indoors around February 11–February 25, then transplant seedlings outdoors around April 15 once the danger of frost has passed.
Never miss a window in Williamstown
An email when it’s time to start seeds, transplant, and sow — timed to Williamstown’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Sicklerville · 7 km
- Pine Hill · 11 km
- Glassboro · 12 km
- Lindenwold · 15 km
- Hammonton · 17 km
- Echelon · 18 km
- Springdale · 21 km
- Bellmawr · 23 km
Frost dates recorded at GLASSBORO 2 NE, 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 Williamstown, NJ — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00283291. Retrieved from https://blissgarden.com/new-jersey/williamstown.