USDA zone 6b in New Jersey
USDA plant hardiness zone 6b covers 11 locations across New Jersey (average annual extreme minimum −5 to 0 °F): Beattystown, NJ, Bernardsville, NJ, Brookside, NJ, Flagtown, NJ, Franklin, NJ, Glen Gardner, NJ, and 5 more. Average last spring frost across this group ranges April 14 (Mountain Lakes) to May 1 (Franklin), and growing seasons run 163–196 days (Layton to Mountain Lakes) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every New Jersey location's own frost dates; the printable planting calendar uses Bernardsville, this group's median-season location.
- USDA zone
- 6b−5 to 0 °F
- Last frost range
- Apr 14–May 1avg, 32°F
- First frost range
- Oct 11–Oct 28avg, 32°F
- Growing season range
- 163–196days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Beattystown | Brass Castle, Vienna, Great Meadows, Hainesburg, Pen Argyl, Wind Gap, +6 more | Belvidere Brg | Apr 30 | Oct 18 | 168 |
| Bernardsville * | Mendham, Long Valley, Chester, Califon | Somerville Somerset Ap | Apr 26 | Oct 18 | 176 |
| Brookside | Mount Tabor, Victory Gardens | Boonton 1 Se | Apr 17 | Oct 23 | 189 |
| Flagtown | — | Wertsville 4 Ne | Apr 16 | Oct 27 | 192 |
| Franklin | Highland Lakes, Vernon Center, Vernon Valley, Warwick, Ogdensburg, Ross Corner, +1 more | Sussex Ap | May 1 | Oct 12 | 164 |
| Glen Gardner | — | Flemington 5 Nnw | Apr 24 | Oct 21 | 179 |
| Hopatcong | Flanders, Lake Hopatcong, Succasunna, Ledgewood, Budd Lake, Hackettstown, +10 more | Andover Aeroflex Ap | Apr 25 | Oct 19 | 175 |
| Kinnelon | Oak Ridge, Newfoundland, Hewitt, Tuxedo Park, Boonton, Hibernia, +2 more | Charlotteburg Rsvr | Apr 25 | Oct 17 | 174 |
| Layton | Crandon Lakes, Pocono Mountain Lake Estates, Birchwood Lakes, Sussex, Milford, Unionville | Sussex 3 Wnw | Apr 30 | Oct 11 | 163 |
| Morris Plains | — | Canoe Brook | Apr 18 | Oct 27 | 189 |
| Mountain Lakes | Mount Tabor | Caldwell Essex Co Ap | Apr 14 | Oct 28 | 196 |
* Bernardsville is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Bernardsville, representative)
Computed from Bernardsville's average frost dates — the median-season location in this New Jerseyzone 6b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Mar 1 – Mar 15 | May 3 – May 10 | Jul 2 – Jul 22 | — | matures comfortably |
| Pepper | Very tender | Feb 15 – Mar 1 | May 10 – May 17 | Jul 9 – Aug 8 | — | matures comfortably |
| Cucumber | Tender | Mar 29 – Apr 5 | May 3 – May 10 | Jun 22 – Jul 12 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | May 3 – May 10 | Jun 17 – Jul 2 | — | matures comfortably |
| Bush bean | Tender | — | May 3 – May 10 | Jun 22 – Jul 2 | Aug 19 – Aug 29 | matures comfortably |
| Sweet corn | Tender | — | Apr 26 – May 10 | Jun 25 – Jul 25 | — | matures comfortably |
| Basil | Very tender | Mar 15 – Mar 29 | May 3 – May 10 | Jun 2 – Jun 17 | — | matures comfortably |
| Lettuce | Half-hardy | Mar 15 – Mar 29 | Mar 29 – Apr 12 | May 13 – May 28 | Aug 5 – Aug 20 | matures comfortably |
| Pea | Hardy | — | Mar 15 – Mar 29 | May 9 – May 24 | Jul 26 – Aug 10 | matures comfortably |
| Spinach | Hardy | — | Mar 15 – Mar 29 | Apr 24 – May 4 | Aug 15 – Aug 25 | matures comfortably |
| Carrot | Half-hardy | — | Apr 5 – Apr 12 | Jun 4 – Jun 24 | Jul 16 – Aug 5 | matures comfortably |
| Broccoli | Half-hardy | Mar 1 – Mar 15 | Mar 29 – Apr 12 | May 23 – Jun 12 | Jul 21 – Aug 10 | matures comfortably |
Which crops fit this growing season
Using Bernardsville's own 176-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Bernardsville)
From NOAA's 1991–2020 Climate Normals at station USW00054785. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | May 7 | May 23 | Oct 7 | Oct 21 | 152 |
| 32°F (freeze) | Apr 26 | May 13 | Oct 18 | Nov 2 | 176 |
| 28°F | Apr 11 | Apr 28 | Oct 30 | Nov 13 | 202 |
| 24°F | Mar 30 | Apr 13 | Nov 11 | Nov 30 | 226 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 11 locations is 3,151; Bernardsville's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,215 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,532 | cool-season crops (brassicas, greens) |
Hardiness zone 6b in New Jersey
Zone 6b means an average annual extreme minimum winter temperature of about −5 to 0 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. New Jersey spans 4 hardiness zones in this dataset — see all New Jersey locations for the full range, including zones7a, 7b, 8a.
Explore zone 6b in other states at zone 6b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 6b mean in New Jersey?
- Zone 6b means an average annual extreme minimum winter temperature of −5 to 0 °F — the standard USDA measure of which perennials survive winter. 11 locations in New Jersey fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in New Jersey's zone 6b is the growing season longest?
- Mountain Lakes runs the longest season on this page at about 196 days; Layton is shortest at about 163 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in New Jersey's zone 6b?
- Using Bernardsville's frost dates (this page's median-season location): start seeds indoors about Mar 1 – Mar 15, then transplant outside about May 3 – May 10. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in New Jersey's zone 6b have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 11 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.