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When to Plant Roses in Coos County, NH

Coos County, New Hampshire Zone 4b June

This month in Coos County, New Hampshire

June is a pivotal month for Coos County, New Hampshire gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 18
Avg. first frost September 30
Soil temp (4") 64°F
Watering Moderate
Pest pressure High
Daylight 15.4 hrs
  1. Time to transplant roses

    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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Roses (Rosa spp.) are the world's most beloved flowering shrubs, grown for centuries for their exquisite blooms, fragrance, and versatility. Modern repeat-blooming cultivars deliver continuous color from late spring through the first hard frost, while old garden roses typically offer a single magnificent spring flush. Hardy shrub roses such as the Knock Out® and Canadian Explorer series tolerate Zone 3–4 winters without protection. With correct siting (6+ hours of sun, good air circulation), disease- resistant varieties thrive with moderate maintenance.

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 Roses to ensure they mature before fall.

Perennial Blooms in Multi-season Pollinator-friendly Good for cutting Fragrant
Coos County, NH (Zone 4b) Short season
135 days
Last Spring Frost May 18
135 growing days
First Fall Frost September 30

Coos County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Roses Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 23 Transplant: May 25 🌸 Bloom: Aug 17 – Nov 2
Recommended (50%) ✗ May not fit
Start indoors: Mar 2 Transplant: Jun 1 🌸 Bloom: Aug 24 – Nov 9
Safe Start (90%) ✗ May not fit
Start indoors: Mar 17 Transplant: Jun 16 🌸 Bloom: Sep 8 – Nov 24

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 Roses's growing requirements.

Soil pH

Your soil pH (5.2–6.6) is more acidic than Roses prefers (6.0–6.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Roses

2"
Planting Depth
36"
Between Plants
48"
Between Rows

Roses Water Budget

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

Monthly Watering Guide for Roses

Roses needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Roses 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 4.3" 3.6" 0.7" 💧 Light watering
Jun 4.3" 3.5" 0.8" 💧 Light watering
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
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.

Roses 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.

Roses needs ~1,755 GDD — county provides 1,755 GDD Tight fit

Roses Planting Timeline — Coos County, NH

Roses Planting Calendar

Activity When Date Range
Start Indoors March 2 Mar 2 – Mar 16
Transplant Outdoors June 1 Jun 1 – Jun 15
Bloom August 24 Aug 24 – Nov 9

Plant 2" deep · 36" apart · Rows 48" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–180 days

🧪 Soil pH

Needs 6–6.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 4b

📆 Growing Season

135 days in Coos County

Growing Tips for Roses in Coos County

Direct sow Roses outdoors after May 18 in Coos County when soil has warmed and frost danger has passed.

Your 135.0-day growing season in Coos County is tight for Roses (90.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Plant bare-root roses in early spring as soon as soil is workable, or set container-grown plants from spring through early fall. Dig a wide, deep hole; amend with compost and a handful of bone meal. Set the graft union 1–2 inches below soil level in Zones 3–6 for winter protection, at soil level in Zones 7+. Water deeply twice weekly until established. Fertilize with a balanced rose food every 4–6 weeks during the growing season. Prune hybrid teas and grandifloras to outward-facing buds in early spring when forsythia blooms. Deadhead to encourage repeat bloom. Fall planting (Zones 5+) can improve establishment in subsequent years. Year 2+ plants deliver the fullest bloom display.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Brassicas

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Roses in Coos County, NH?

Coos County is in Zone 4b with an average last frost of May 18. Plan your Roses 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 22-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: June 2026.

Sources & credits

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