Trenton, New Jersey: planting zone & frost dates
Trenton is in USDA plant hardiness zone 7a, where the average coldest winter night reaches 0 to 5°F (-17.8 to -15.0°C). The typical last spring frost is around Apr 25 and the first fall frost around Oct 21.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 6 | Oct 11 |
| Typical planning date (30% risk) | Apr 25 | Oct 21 |
| Median (50%) | Apr 17 | Oct 28 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station TRENTON STATE COLLEGE, NJ (USC00288880), 3.6 mi (5.8 km) from the city center and 46 ft higher than the city center (+14 m). Record used for the 1991–2020 normals: 11 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Trenton
Trenton spans more than one half-zone. Share of the city's land area by zone (via its 7 ZIP codes): 7a (61%), 7b (39%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Trenton
Dates are counted from the 30%-risk frost dates above (last frost Apr 25, first frost Oct 21). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 28 – Mar 14 | May 2 – May 16 | — | — |
| Pepper | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Lettuce | Mar 14 – Mar 28 | Apr 11 – May 2 | Mar 28 – May 9 | Aug 12 – Sep 9 |
| Green Beans | — | — | May 2 – Jun 6 | Jul 29 – Aug 12 |
| Sweet Corn | — | — | May 2 – May 30 | — |
| Zucchini & Summer Squash | Mar 28 – Apr 4 | May 2 – May 16 | May 2 – May 23 | Jul 29 – Aug 12 |
| Cucumber | Mar 28 – Apr 4 | May 9 – May 16 | May 2 – May 23 | Jul 29 – Aug 12 |
| Carrot | — | — | Apr 4 – May 9 | Jul 29 – Aug 12 |
| Onion | Jan 31 – Feb 14 | Mar 28 – Apr 11 | — | — |
| Potato | — | Mar 28 – Apr 18 | — | — |
| Basil | Mar 14 – Mar 28 | May 9 – May 23 | May 9 – May 30 | — |
| Spinach | — | — | Mar 14 – Apr 11 | Aug 26 – Sep 23 |
| Kale | Feb 28 – Mar 14 | Mar 28 – Apr 18 | Mar 28 – Apr 18 | Aug 12 – Sep 9 |
| Broccoli | Feb 28 – Mar 14 | Apr 11 – May 2 | — | Jul 29 – Aug 12 |
| Peas | — | — | Mar 14 – Apr 4 | Aug 12 – Aug 26 |
| Eggplant | Feb 14 – Feb 28 | May 9 – May 23 | — | — |
| Cabbage | Feb 28 – Mar 14 | Mar 28 – Apr 11 | — | Jul 29 – Aug 12 |
| Radish | — | — | Mar 21 – May 9 | Sep 9 – Oct 7 |
| Strawberry | — | Mar 28 – Apr 18 | — | — |
| Beets | — | — | Apr 4 – May 16 | Aug 12 – Aug 26 |
Nearby cities in New Jersey
- Elizabeth — zone 7b, last frost Apr 6, first frost Nov 4
- Newark — zone 7b, last frost Apr 8, first frost Nov 1
- Jersey City — zone 7b, last frost Apr 8, first frost Nov 1
- Clifton — zone 7a, last frost Apr 20, first frost Oct 22
- Paterson — zone 7a, last frost Apr 20, first frost Oct 22
More: all New Jersey cities · other zone 7a cities: Louisville, KY, Wichita, KS, Cleveland, OH, Lexington, KY, St. Louis, MO, Boise, ID, Amarillo, TX, Providence, RI
Trenton gardening questions
When is the last frost in Trenton, NJ?
Plan around Apr 25. At NOAA's Trenton State College, NJ station, 3.6 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 17, and after May 6 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 2. The 90% and 10% dates are 34 days apart, close to the 36-day median for cities on this site.
When should I plant tomatoes in Trenton, NJ?
Start seeds indoors Feb 28 – Mar 14 and set transplants outside May 2 – May 16, once nights stay above 50°F and the soil is near 60°F. That leaves 179 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Trenton?
About 192 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 168 days, and in 1 year in 10 it runs 214 days or more. In fall there is a 10% chance of frost by Oct 11 and a 30% chance by Oct 21. That is the shortest of the 6 New Jersey cities on this site.
When should I plant a fall garden in Trenton?
Count back from the first fall frost (Oct 21): transplant broccoli Jul 29 – Aug 12; sow kale Aug 12 – Sep 9; sow lettuce Aug 12 – Sep 9; sow radishes Sep 9 – Oct 7. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 7. How the math works: succession and fall planting.
Did Trenton's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Trenton is zone 7a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of Trenton in zone 7a?
No. Zone 7a covers about 61% of the city's land; the rest is in 7b (39%), measured across the city's 7 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.