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When to Plant Kale in Coos County, NH

Coos County, New Hampshire Zone 4b May

This month in Coos County, New Hampshire

Welcome to May in Zone 4b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 18
Avg. first frost September 30
Soil temp (4") 54°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Plant out kale

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

  2. Outdoor sowing time: kale

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Looking ahead to 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.

Coos County, New Hampshire is in USDA Zone 4b. The average last spring frost is May 18 and the first fall frost is September 30, giving you a growing season of approximately 135 days.

At an elevation of 604 feet, Coos County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Kale to ensure they mature before fall.

Coos County, NH (Zone 4b) Short season
135 days
Last Spring Frost May 18
135 growing days
First Fall Frost September 30
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Coos County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (20 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Jul 6 – Aug 31
Recommended (50%) ✓ Fits season (23 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jul 13 – Sep 7
Safe Start (90%) ✓ Fits season (25 days to spare)
Start indoors: Apr 21 Transplant: Jun 2 🍅 Harvest: Jul 28 – Sep 22

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 Coos County

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

Soil pH

Your soil pH (5.2–6.6) is more acidic than Kale prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Kale.

How to Plant Kale

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Kale

3
successive plantings in your 135-day season

Sow every 5.7 weeks. Last sowing by Jul 22 to harvest before frost.

For a dedicated fall crop, sow by Jul 08.

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 3.2" 0" ❄️ Dormant
Feb 2.9" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 3.5" 3.6" 0" ✅ Rainfall sufficient
Jun 3.5" 3.5" 0" ✅ Rainfall sufficient
Jul 3.5" 3.9" 0" ✅ Rainfall sufficient
Aug 3.5" 4" 0" ✅ Rainfall sufficient
Sep 3.5" 3.7" 0" ✅ Rainfall sufficient
Oct 3.1" 0" ❄️ Dormant
Nov 3.1" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Coos 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 ~780 GDD — county provides 1,755 GDD Excellent fit

Kale Planting Timeline — Coos County, NH

Kale Planting Calendar

Activity When Date Range
Start Indoors April 6 Apr 6 – Apr 20
Transplant Outdoors May 18 May 18 – Jun 1
Direct Sow May 11 May 11 – Jun 1
Harvest July 13 Jul 13 – Sep 7
Fall Sowing July 8 Jul 8 – Jul 22

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing Harvest
August Harvest
September Harvest
October
November
December
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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 4b

📆 Growing Season

135 days in Coos County

Growing Tips for Kale in Coos County

Direct sow Kale outdoors after May 18 in Coos 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 Coos County, NH?

Coos County is in Zone 4b with an average last frost of May 18. Plan your Kale planting based on this frost date — see the calendar above for exact timing.

What planting zone is Coos County, NH?

Coos County, New Hampshire is in USDA Hardiness Zone 4b. The average last spring frost is May 18 and first fall frost is September 30.

🌱

Your Coos County Garden Planner — Free

A 24-page printable planner built for Coos County (Zone 4b). 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 Coos 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.