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When to Plant Thyme in Rockingham County, NH

Rockingham County, New Hampshire Zone 5b April

April in the garden — Rockingham County, New Hampshire

A quick April briefing for Rockingham County, New Hampshire gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 26
Avg. first frost October 17
Soil temp (4") 44°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
Get ahead of May
  • Transplants going out: thyme

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Thyme is a low-growing perennial herb with tiny, aromatic leaves and a warm, earthy flavor. It is one of the most versatile culinary and medicinal herbs.

Rockingham County, New Hampshire is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 17, giving you a growing season of approximately 174 days.

At an elevation of 444 feet, Rockingham County receives approximately 50 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Thyme to ensure they mature before fall.

Rockingham County, NH (Zone 5b) Moderate season
174 days
Last Spring Frost April 26
174 growing days
First Fall Frost October 17

Rockingham County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Transplant: Apr 27 🍅 Harvest: Jul 6 – Sep 7
Recommended (50%) ✓ Fits season (34 days to spare)
Transplant: May 3 🍅 Harvest: Jul 12 – Sep 13
Safe Start (90%) ✓ Fits season (32 days to spare)
Transplant: May 20 🍅 Harvest: Jul 29 – Sep 30

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 Rockingham County

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

Soil pH

Your soil pH (5.2–6.4) is more acidic than Thyme prefers (6.0–8.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Thyme.

How to Plant Thyme

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Thyme

2
successive plantings in your 174-day season

Sow every 8 weeks. Last sowing by Jul 19 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Thyme

Thyme needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Thyme Needs Rainfall You Supplement Action
Jan 3.8" 0" ❄️ Dormant
Feb 3.1" 0" ❄️ Dormant
Mar 4.2" 0" ❄️ Dormant
Apr 1.3" 3.9" 0" ✅ Rainfall sufficient
May 1.3" 5" 0" ✅ Rainfall sufficient
Jun 1.3" 4.9" 0" ✅ Rainfall sufficient
Jul 1.3" 4.3" 0" ✅ Rainfall sufficient
Aug 1.3" 4.6" 0" ✅ Rainfall sufficient
Sep 1.3" 4.5" 0" ✅ Rainfall sufficient
Oct 1.3" 4.4" 0" ✅ Rainfall sufficient
Nov 3.5" 0" ❄️ Dormant
Dec 4" 0" ❄️ Dormant

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

Thyme 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.

Thyme needs ~980 GDD — county provides 2,131 GDD Excellent fit

Thyme Planting Timeline — Rockingham County, NH

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors May 3 May 3 – May 17
Harvest July 12 Jul 12 – Sep 13

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–8 · Your soil: too_acidic

🗺️ USDA Zone

Zone 5b

📆 Growing Season

174 days in Rockingham County

Growing Tips for Thyme in Rockingham County

Direct sow Thyme outdoors after April 26 in Rockingham County when soil has warmed and frost danger has passed.

General growing tips

Start from seed, cuttings, or divisions. Plant in well-drained, lean soil. Prune lightly after flowering. Replace plants every 3-4 years when they become woody.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Thyme in Rockingham County, NH?

Rockingham County is in Zone 5b with an average last frost of April 26. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rockingham County, NH?

Rockingham County, New Hampshire is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 17.

🌱

Your Rockingham County Garden Planner — Free

A 24-page printable planner built for Rockingham 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.

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 Rockingham County, NH. Local conditions may vary. Last updated: April 2026.

Sources & credits

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