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When to Plant Kale in Grafton County, NH

Grafton County, New Hampshire Zone 5a May

Your May planting checklist for Grafton County, New Hampshire

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. Time to transplant kale

    Your last frost (May 12) has passed. These warm-season crops can handle outdoor soil now.

Get ahead of June
  • Starting indoors: kale

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Kale is an exceptionally hardy, nutrient-dense green available in curly, lacinato, and Russian varieties. It tolerates heavy frost and often tastes sweeter after cold exposure.

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 Kale 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 (38 days to spare)
Start indoors: Apr 1 Transplant: May 6 🍅 Harvest: Jul 1 – Aug 26
Recommended (50%) ✓ Fits season (36 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jul 7 – Sep 1
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Apr 20 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 14

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 Kale's growing requirements.

Soil pH

Your soil pH (5.2–6.3) is more acidic than Kale prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Kale

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Kale

3
successive plantings in your 148-day season

Sow every 5.7 weeks. Last sowing by Jul 29 to harvest before frost.

For a dedicated fall crop, sow by Jul 29.

Plant Water Budget

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

Monthly Watering Guide for Kale

Kale needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Kale 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 3.5" 3.6" 0" ✅ Rainfall sufficient
Jun 3.5" 4.5" 0" ✅ Rainfall sufficient
Jul 3.5" 4.9" 0" ✅ Rainfall sufficient
Aug 3.5" 3.9" 0" ✅ Rainfall sufficient
Sep 3.5" 3.6" 0" ✅ Rainfall sufficient
Oct 3.5" 3.6" 0" ✅ Rainfall sufficient
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.

Kale 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.

Kale needs ~600 GDD — county provides 1,480 GDD Excellent fit

Kale Planting Timeline — Grafton County, NH

Kale Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 12 May 12 – May 26
Direct Sow April 28 Apr 28 – May 19
Harvest July 7 Jul 7 – Sep 1
Fall Sowing July 29 Jul 29 – Aug 12

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5a

📆 Growing Season

148 days in Grafton County

Growing Tips for Kale in Grafton County

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

Common pests for Kale in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow or transplant in early spring or late summer. Harvest outer leaves first to keep plants productive. Kale overwinters in many climates and can provide greens all year.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Kale Seeds
Life Cycle Biennial
Pollination Cross-Pollinated (insects)
How to Collect Allow 2nd year flower stalks to dry. Harvest pods when tan.
Storage Store airtight; viable 5 years at 35°F, under 50% humidity.

Isolate 1/2 mile from other brassicas (broccoli, cabbage, etc.) — they all cross.

Frequently Asked Questions

When should I plant Kale in Grafton County, NH?

Grafton County is in Zone 5a with an average last frost of May 12. Plan your Kale 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.

Instant PDF download. No spam, unsubscribe any time.

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.