When to Plant Tomatoes in Sullivan County, NH
Your May gardening checklist
We've pulled the most time-sensitive tasks for Sullivan County, New Hampshire this May and put them front and centre. Tackle them in order.
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Move tomatoes into the garden
Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.
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Seed tomatoes outdoors
Your soil is 59°F — warm enough for these to germinate without babying.
Tomatoes are the most popular home garden crop, available in thousands of varieties from tiny cherries to massive beefsteaks. They are warm-season plants needing full sun.
Sullivan County, New Hampshire is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is October 7, giving you a growing season of approximately 148 days.
At an elevation of 495 feet, Sullivan County receives approximately 39.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Tomatoes to ensure they mature before fall.
Sullivan County Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.6
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Sullivan County
How your county's soil matches Tomatoes's growing requirements.
Soil pH
Your soil pH (5.0–6.6) is more acidic than Tomatoes prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Sullivan County is excellent for Tomatoes — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.1%). Annual compost additions will help Tomatoes.
How to Plant Tomatoes
Succession Planting Tomatoes
Sow every 6.9 weeks. Last sowing by Jul 14 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Tomatoes
Tomatoes needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.
| Month | Tomatoes Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.7" | 0" | ❄️ Dormant |
| Feb | — | 2.9" | 0" | ❄️ Dormant |
| Mar | — | 3.6" | 0" | ❄️ Dormant |
| Apr | — | 3.6" | 0" | ❄️ Dormant |
| May | 5.2" | 3.6" | 1.6" | 💧 Light watering |
| Jun | 5.2" | 3.3" | 1.9" | 💧 Light watering |
| Jul | 5.2" | 4.3" | 0.9" | 💧 Light watering |
| Aug | 5.2" | 3.3" | 1.9" | 💧 Light watering |
| Sep | 5.2" | 3.2" | 2" | 💧 Light watering |
| Oct | 5.2" | 3.1" | 2.1" | 💧 Light watering |
| Nov | — | 3" | 0" | ❄️ Dormant |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Sullivan County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Tomatoes Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Tomatoes Planting Timeline — Sullivan County, NH
Tomatoes Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | May 26 | May 26 – Jun 9 |
| Direct Sow | May 19 | May 19 – Jun 9 |
| Harvest | July 28 | Jul 28 – Oct 6 |
Plant 0.5" deep · 24" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.2"/week · Only during dry spells
📅 Days to Maturity
60–85 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
148 days in Sullivan County
Growing Tips for Tomatoes in Sullivan County
Direct sow Tomatoes outdoors after May 12 in Sullivan County when soil has warmed and frost danger has passed.
Common pests for Tomatoes in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 6-8 weeks before last frost. Bury transplants deep to encourage rooting along the stem. Provide consistent moisture to prevent blossom end rot and cracking.
Recommended Tomatoes Varieties for Sullivan County
Choose determinate, early-maturing varieties for your short season
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Isolate 25 ft between varieties for purity. Use open-pollinated varieties for true-to-type seeds.
Tomatoes in Other Locations
Frequently Asked Questions
When should I plant Tomatoes in Sullivan County, NH?
Sullivan County is in Zone 5b with an average last frost of May 12. Plan your Tomatoes planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sullivan County, NH?
Sullivan County, New Hampshire is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is October 7.
Your Sullivan County Garden Planner — Free
A 24-page printable planner built for Sullivan County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.