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When to Plant Eggplant in Grafton County, NH

Grafton County, New Hampshire Zone 5a May

Grafton County, New Hampshire gardeners: here's your May plan

Your garden in Grafton County, New Hampshire is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 12
Avg. first frost October 7
Soil temp (4") 54°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Plant out eggplant

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Sow eggplant where they'll grow

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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Eggplant is a heat-loving solanaceous crop that produces glossy fruits in purple, white, or striped varieties. It requires long, warm growing seasons for best production.

Grafton County, New Hampshire is in USDA Zone 5a. 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 524 feet, Grafton County receives approximately 44.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Eggplant to ensure they mature before fall.

Grafton County, NH (Zone 5a) Short season
148 days
Last Spring Frost May 12
148 growing days
First Fall Frost October 7

Grafton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Start indoors: Feb 25 Transplant: May 20 🍅 Harvest: Jul 29 – Sep 30
Recommended (50%) ✓ Fits season (1 days to spare)
Start indoors: Mar 3 Transplant: May 26 🍅 Harvest: Aug 4 – Oct 6
Safe Start (90%) ✓ Fits season (1 days to spare)
Start indoors: Mar 16 Transplant: Jun 8 🍅 Harvest: Aug 17 – Oct 19

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 Grafton County

How your county's soil matches Eggplant's growing requirements.

Soil pH

Your soil pH (5.2–6.3) overlaps with Eggplant's range (5.5–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Grafton County is excellent for Eggplant — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.5%). Annual compost additions will help Eggplant.

How to Plant Eggplant

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Eggplant

2
successive plantings in your 148-day season

Sow every 7.4 weeks. Last sowing by Jul 14 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Eggplant

Eggplant needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Eggplant Needs Rainfall You Supplement Action
Jan 3.5" 0" ❄️ Dormant
Feb 3.3" 0" ❄️ Dormant
Mar 3.2" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.8" 3.6" 1.2" 💧 Light watering
Jun 4.8" 4.5" 0.3" 💧 Light watering
Jul 4.8" 4.9" 0" ✅ Rainfall sufficient
Aug 4.8" 3.9" 0.9" 💧 Light watering
Sep 4.8" 3.6" 1.2" 💧 Light watering
Oct 4.8" 3.6" 1.2" 💧 Light watering
Nov 3.5" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Grafton County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Eggplant 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.

Eggplant needs ~750 GDD — county provides 1,480 GDD Excellent fit

Eggplant Planting Timeline — Grafton County, NH

Eggplant Planting Calendar

Activity When Date Range
Start Indoors March 3 Mar 3 – Mar 17
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest August 4 Aug 4 – Oct 6

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July
August Harvest
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Natural rainfall sufficient

📅 Days to Maturity

65–85 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

148 days in Grafton County

Growing Tips for Eggplant in Grafton County

Direct sow Eggplant outdoors after May 12 in Grafton County when soil has warmed and frost danger has passed.

Common pests for Eggplant 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 8-10 weeks before last frost. Transplant only after nighttime temperatures stay above 55F. Mulch to retain moisture and warmth around roots.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Kohlrabi

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Eggplant in Grafton County, NH?

Grafton County is in Zone 5a with an average last frost of May 12. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Grafton County, NH?

Grafton County, New Hampshire is in USDA Hardiness Zone 5a. The average last spring frost is May 12 and first fall frost is October 7.

🌱

Your Grafton County Garden Planner — Free

A 24-page printable planner built for Grafton County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Grafton County, NH. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.