Frost dates for Trenton, New Jersey
In Trenton, half of springs have had their last frost by April 10 (and 1 spring in 10 still has one after April 25), and half of falls have had their first frost by November 1, leaving about 202 frost-free days in a typical year. Here is how sure those dates are, what they mean for planting, and where they come from.
Frost dates for
Trenton, New Jersey
Last spring frost
April 10
Half of springs have their last frost by this date. For a safer bet, wait until April 25: only 1 spring in 10 has a frost after that.
First fall frost
November 1
Half of falls have their first frost by this date. In 1 fall in 10 it comes by October 15.
Growing season
202 days
Frost-free days in a typical year. 9 years in 10 get at least 180.
Hardiness zone
Not listed
This ZIP code isn't in the USDA's ZIP code list for the 2023 map.
Stations near you disagree. NOAA's Trenton Mercer Co Airport (5 miles away, at 180 feet above sea level), the one we used, gives a typical last frost of April 10 and a typical first frost of November 1. NOAA's Hightstown 2 W (10 miles away, at 100 feet above sea level) gives a typical last frost of April 25 and a typical first frost of October 16. So the typical last frost could fall anywhere from April 10 to 25 and the typical first frost from October 16 to November 1, depending on whether your garden is more like one or the other. Local terrain matters: hillsides, valley floors, water and city heat can change frost dates a lot over a few miles. Treat the dates here as a starting point, and compare with a nearby gardener or your county extension office.
Print a year planner for Trenton
Frost risk through the year
How sure are these dates?
A frost date is a probability, not a promise. NOAA worked out, from 30 years of nightly lows, how often the last spring frost and the first fall frost fall on each date. The middle column is the typical year. The outer columns are the early and late years that come about once a decade.
| Early year 1 in 10 | Typical year 1 in 2 | Late year 1 in 10 | |
|---|---|---|---|
| Last frost in spring | March 30 | April 10 | April 25 |
| First frost in fall | October 15 | November 1 | November 13 |
The frost-free season between them runs 202 days in a typical year. In 1 year in 10 it is 223 days or longer, and in 1 year in 10 it is 180 days or shorter.
- Hard freeze (28°F): typically last on March 31 and first on November 12. It is a harder freeze than the 32°F frost line, cold enough to damage many garden plants; how hardy a crop is decides whether it comes through. (The National Weather Service's own hard-freeze threshold varies from office to office.)
- Frost possible (36°F at the station): typically last on April 25 and first on October 20. On clear, still nights the ground can be several degrees colder than the thermometer, so frost can form on plants when the official reading is in the mid-30s.
In 8 springs out of 10, the last frost in Trenton comes between March 30 and April 25, a window of 26 days. That is narrower than at most NOAA stations (the typical window is 31 days), so the typical date is a steadier guide here than in most places.
Among New Jersey's 48 NOAA stations with a frost every year, 77 percent have their typical last frost later than Trenton does.
Planting calendar for Trenton
These dates count from the typical last and first frosts, using the planting rules published by Colorado State University Extension (spring), Virginia Cooperative Extension (fall crops) and University of Minnesota Extension (garlic, where winters are hard). Weather in any one year can run early or late, so check the forecast before you plant tender crops.
| When | What to do | Why then |
|---|---|---|
| January | ||
| January 23 to February 20 | Broccoli and cabbage Start seeds indoors | 5 to 7 weeks before planting them out |
| February | ||
| February 6 to March 6 | Cauliflower Start seeds indoors | 5 to 7 weeks before planting out |
| February 20 to March 13 | Eggplant Start seeds indoors | 6 to 9 weeks before planting out |
| February 27 to March 13 | Peppers Start seeds indoors | 6 to 8 weeks before planting out |
| March | ||
| March 6 to 20 | Tomatoes Start seeds indoors | 5 to 7 weeks before planting out |
| March 13 to 27 | Peas, spinach, lettuce, radishes, onion sets, turnips Sow outdoors, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 13 to 27 | Broccoli and cabbage Plant out, as early as | hardy crops: 2 to 4 weeks before the typical last frost |
| March 27 to April 10 | Beets, carrots, potatoes, Swiss chard Plant outdoors, as early as | semi-hardy crops: up to 2 weeks before the typical last frost |
| March 27 to April 10 | Cauliflower Plant out, as early as | semi-hardy: up to 2 weeks before the typical last frost |
| April | ||
| April 10 | Snap beans, sweet corn, cucumbers, summer squash Sow outdoors around | tender crops: around the typical last frost date |
| April 24 | Tomatoes, peppers, eggplant Plant out from | very tender: 2 weeks or more after the typical last frost |
| April 24 | Melons, winter squash, pumpkins, lima beans Sow outdoors from | very tender: 2 weeks or more after the typical last frost |
| June | ||
| June 6 to 20 | Cabbage for fall Start seeds | set the plants out by July 25 |
| June 26 to July 10 | Broccoli for fall Start seeds | set the plants out by August 14 |
| August | ||
| August 5 | Snap beans for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 9 | Carrots for fall Last date to sow | 70 days to harvest, plus 2 weeks for slower fall growth |
| August 10 | Cucumbers for fall Last date to sow | 55 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 14 | Peas for fall Last date to sow | 65 days to harvest, plus 2 weeks for slower fall growth |
| August 15 | Summer squash for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth, plus 2 weeks because frost kills it |
| August 19 | Leaf lettuce and beets for fall Last date to sow | 60 days to harvest, plus 2 weeks for slower fall growth |
| August 29 | Turnips and kohlrabi for fall Last date to sow | 50 days to harvest, plus 2 weeks for slower fall growth |
| September | ||
| September 8 | Spinach for fall Last date to sow | 40 days to harvest, plus 2 weeks for slower fall growth |
| September 18 | Radishes for fall Last date to sow | 30 days to harvest, plus 2 weeks for slower fall growth |
| October | ||
| October 15 | Tomatoes, peppers, squash, melons, cucumbers Watch the forecast from | in 1 fall in 10 the first frost comes by this date; pick tender crops before a frost |
| November | ||
| November 19 to 26 | Garlic Plant cloves | one or two weeks after the typical first hard freeze (28°F), our reading of the first killing frost |
Want more insurance? Shift every spring date 15 days later. That plans around April 25, the date after which only 1 spring in 10 has a frost.
For spring bulbs such as tulips and daffodils, plant once the soil has cooled to about 50 to 55°F and keep going until a couple of weeks before the ground freezes. Our guide to fall planting explains how to tell.
Where these numbers come from
These dates come from NOAA's weather station Trenton Mercer Co Airport (station USW00014792), 5 miles from the center of Trenton. It sits 120 feet higher, at 180 feet above sea level. NOAA rates this station's record as representative: at least 10 of the 30 years, with the gaps filled from nearby stations.
The same station also gives the frost dates for Princeton.
Our ZIP code lookup matches these 6 ZIP codes to the same station, so they get the same dates: 08534, 08560, 08628, 18940, 18977, 19067. Hardiness zones are worked out separately for each ZIP code.
Nearby places
- Philadelphia, Pennsylvania: last frost around April 4, first frost around November 7 (25 miles away)
- Allentown, Pennsylvania: last frost around April 20, first frost around October 24 (45 miles away)
- Newark, New Jersey: last frost around April 2, first frost around November 10 (45 miles away)
See frost dates across New Jersey, or look up your own ZIP code for the station nearest you. Want the background? Read what a last frost date really means.