In most of New Jersey, you can safely transplant tomatoes outdoors between mid-May and early June, after the last frost has passed and soil temperatures reach at least 55°F. The exact timing depends on where you are in the state, since northern and southern New Jersey have different frost schedules separated by roughly two weeks.
Last Frost Dates Across New Jersey
New Jersey spans multiple USDA hardiness zones, which means spring arrives earlier in the southern counties than in the north. In the southern part of the state, from around Trenton down through Camden and Cape May, the average last frost falls in mid to late April. Central New Jersey typically sees its last frost in late April to early May. Northern counties, including Sussex, Passaic, and Morris, may not be frost-free until mid-May or even later in higher elevations.
These are averages, not guarantees. A surprise frost can hit a week or two after the “average last frost” date, so many experienced NJ gardeners wait an extra week or two beyond that date before putting tomatoes in the ground. For southern NJ, that means transplanting around May 10 to 15. For central NJ, aim for May 15 to 25. For northern NJ, late May through the first week of June is the safer window.
Soil Temperature Matters More Than Air Temperature
A warm sunny day in late April can be misleading. Tomatoes need soil temperatures of at least 55 to 60°F to develop healthy roots after transplanting. Below that range, plants sit dormant, become stressed, and are more vulnerable to disease. You can check soil temperature with an inexpensive probe thermometer pushed about 4 inches into the ground. Take readings in the morning, when the soil is coolest, for the most accurate number.
In practice, NJ soils don’t consistently hit 60°F until mid-May in most areas. Raised beds warm up faster than in-ground plots, so if you garden in raised beds, you may be able to transplant a week earlier than your neighbors growing in the ground.
Starting Seeds Indoors
If you’re growing tomatoes from seed rather than buying transplants, start them indoors 5 to 6 weeks before your planned outdoor planting date. For most of New Jersey, that means sowing seeds between early and mid-April. Southern NJ gardeners can start as early as late March.
Use a seed-starting mix in small pots or cell trays, keep them in a warm spot (around 70 to 75°F), and provide strong light once seedlings emerge. A sunny south-facing window can work, but a simple grow light kept a few inches above the seedlings produces sturdier, stockier plants. Before moving them outside, harden them off by setting them outdoors in a sheltered spot for a few hours each day over the course of a week, gradually increasing their exposure to direct sun and wind.
Protecting Early Transplants From Late Frost
If you want to push your planting date a couple of weeks earlier, frost protection makes it possible. Plastic sheeting stretched over short garden stakes works well for raised beds or in-ground rows. The key is keeping the plastic from touching the plants directly, since that air gap provides the insulation. Old bedsheets and lightweight fleece blankets also work in a pinch.
For individual plants, glass or plastic cloches are ideal. If you don’t have those, upturned buckets, empty pots, or even large plastic cups can shield a single transplant from an overnight frost. Just remember to remove covers in the morning so plants get sunlight and airflow. This approach lets some NJ gardeners transplant as early as late April in central areas, though it does require watching the forecast closely every night.
Best Varieties for New Jersey
New Jersey’s hot, humid summers make disease resistance an important factor when choosing varieties. Rutgers University has tested dozens of cultivars in NJ conditions and publishes specific recommendations. Here are some of the top performers, organized by how quickly they produce fruit.
Early Season (49 to 72 Days)
- Fourth of July: One of the fastest to harvest at 49 days. Small 4-ounce fruits on indeterminate vines with strong disease resistance.
- Early Girl: Ready in about 50 days, producing 4-ounce fruits. A reliable choice if you want tomatoes on the table by mid-July.
- Red Deuce: A determinate plant producing large 10-ounce fruits in about 72 days, with good disease resistance for NJ’s humid conditions.
Mid-Season (66 to 78 Days)
- Celebrity: A semi-determinate variety with excellent disease resistance and 10-ounce fruits. One of the most dependable all-around choices for NJ gardens.
- Better Boy: Large 12-ounce fruits on indeterminate vines. A classic backyard slicer that performs well in NJ heat.
- Big Beef: Produces 10-ounce fruits with broad disease resistance, including tolerance to tobacco mosaic virus.
- Rutgers 250: A semi-determinate variety developed at Rutgers University, producing 10-ounce fruits with the flavor profile of the original Rutgers tomato that helped make NJ famous for tomatoes.
- Mountain Magic: Smaller 2-ounce fruits but notable for its resistance to early blight, one of the most common fungal problems in NJ gardens.
Late Season (85 Days)
- Ramapo: Another Rutgers-bred variety, producing large 12-ounce fruits prized for their flavor. Requires a long growing season, so plant it on time to ensure harvest before fall frost.
Determinate varieties grow to a fixed size and produce most of their fruit within a few weeks, making them good for canning. Indeterminate varieties keep growing and producing until frost kills them, giving you a steady supply through the season.
Planting Tips for NJ Conditions
Bury tomato transplants deep. Strip off the lower leaves and set the plant so that two-thirds of the stem is underground. Tomatoes grow roots along buried stems, and a deeper root system helps plants access moisture during NJ’s sometimes dry July and August stretches.
Space plants 24 to 36 inches apart for determinate types and 36 to 48 inches apart for indeterminate types. New Jersey’s summer humidity creates ideal conditions for fungal diseases like early blight and septoria leaf spot. Good spacing improves airflow around the foliage, which is one of the simplest ways to reduce disease pressure. Staking or caging plants to keep foliage off the ground helps for the same reason.
Mulch around the base of plants with straw, shredded leaves, or untreated wood chips once the soil has warmed. This conserves moisture, suppresses weeds, and prevents soil from splashing onto lower leaves during rain, which is a common way fungal spores spread. Water at the base of the plant rather than overhead to keep foliage dry.
NJ’s growing season is long enough to harvest even late-season varieties if you transplant by early June. The first fall frost typically arrives in mid to late October in southern NJ and early to mid-October in the north, giving you roughly 4 to 5 months of growing time from a mid-May transplant.