When to Plant Tomatoes in New Hampshire
Published: April 21, 2026
New Hampshire gardeners in Zone 5b have a 28-week frost-free window for tomato (April 7 to October 22). Warm-season crops like tomato must be started indoors early to maximize the short window — New Hampshire's late spring and early fall frost dates leave little room for error. This guide gives exact dates for New Hampshire based on your local frost calendar.
Tomato Planting Dates for New Hampshire
| Start seeds indoors | February 24–March 3 |
| Last frost (average) | April 7 |
| Transplant outdoors | April 21–May 1 |
| Expect first harvest | June 20 – July 15 |
| Fall crop start | July 30–August 9 |
| Fall harvest | September 28 |
| First fall frost (average) | October 22 |
Dates above assume Zone 5b, the most common zone in New Hampshire. Gardeners in cooler Nashua (Zone 5b) plant 1–2 weeks later; warmer Portsmouth (Zone 5a) can plant 1–2 weeks earlier.
⚠ Warm-climate gardeners (TX, FL, AZ) can grow TWO crops: spring (Feb–March transplant) and fall (July transplant for October harvest).
Growing Tomatoes in New Hampshire's Climate
New Hampshire's cold Zone 5b climate puts warm-season tomato at the edge of viability — but the edge is workable with good planning. Starting seeds indoors under lights in late winter is the most important step; skipping this puts the whole harvest at risk from the short outdoor growing window.
Season extenders pay for themselves many times over in New Hampshire. Row covers placed over transplants in early spring add 5°F to 8°F of protection and can extend the season two to three weeks on each end. Black plastic mulch warms the soil to the temperatures tomato needs for aggressive root growth.
Common tomato pests to watch for in New Hampshire include Tomato Hornworm and Aphids. The first line of defense is companion planting: Basil and Marigold planted nearby discourage several of these pests by confusing host-plant identification or repelling adults before they can lay eggs. Weekly garden walks in the early morning catch problems when they're still manageable.
Tomato Garden Calendar for New Hampshire
| Month | Task | Notes |
|---|---|---|
| January | — | Dormant season |
| February | Start seeds indoors | Use grow lights; warm soil to 70–75°F for best germination |
| March | — | Dormant season |
| April | Transplant outdoors | Soil temp must be 60°F+; nighttime lows above 50°F |
| May ← | — | Dormant season |
| June | Peak growth; water 1 inch/week | Monitor for pests daily; stake or support as needed |
| July | Start fall crop seeds | Fall transplants go in 12 weeks before first frost |
| August | — | Dormant season |
| September | — | Dormant season |
| October | First frost approaches | Harvest remaining tomato; cover plants on frost nights |
| November | — | Dormant season |
| December | — | Dormant season |
Tomato Growing Tips for New Hampshire Gardeners
- •Bury the stem 2/3 deep when transplanting — roots grow from the buried stem for a stronger plant.
- •Consistent watering prevents blossom end rot and fruit cracking; uneven moisture causes both.
- •New Hampshire's short growing season means start seeds indoors under grow lights — don't rely on windowsill light which produces leggy, weak seedlings that struggle outdoors.
- •Cover young transplants with floating row covers for the first 2–3 weeks outside. The 3–5°F of protection reduces frost damage risk and accelerates early growth.
- •Stop heavy nitrogen once flowers appear — it causes leafy plants with few tomatoes.
Companion Planting for Tomatoes in New Hampshire
In New Hampshire's cold climate, planting tomato with Basil and Marigold helps deter pests and improve soil. Avoid planting near Potato and Fennel, which inhibit tomato growth through root chemistry or shared pest pressure. See the full tomato companion planting guide for the complete list.
Tomatoes Planting Dates by City in New Hampshire
Top cities in New Hampshire — select for city-level frost dates and planting calendars.
Frequently Asked Questions
When should I plant tomato in New Hampshire?
In New Hampshire (Zone 5b), start tomato seeds indoors around February 24–March 3 and transplant outdoors around April 21–May 1 — 2 weeks after the state's average last frost of April 7.
What is the last frost date in New Hampshire?
New Hampshire's average last frost date is April 7 in the state's most common Zone 5b. Frost dates vary by city — higher elevations and northern counties run 1 to 3 weeks later than the state average. See the city list below for city-level frost dates.
Can I grow tomato year-round in New Hampshire?
Not year-round — New Hampshire's cold season stops tomato production. The tomato season runs April 7 to October 22, roughly 28 weeks. A fall crop extends harvest into late autumn.
What tomato varieties grow best in New Hampshire?
For New Hampshire's Zone 5b, Early-maturing varieties like Early Girl, Fourth of July, and Stupice (60 days) produce before frost cuts the season short.
When do I start tomato seeds indoors in New Hampshire?
Start tomato seeds indoors in New Hampshire around February 24–March 3, which is 6 weeks before the state's average last frost of April 7. Use grow lights and keep soil temperatures at 70–75°F for fastest germination.