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When to Plant Thyme in Northumberland County, PA

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.

Northumberland County, Pennsylvania is in USDA Zone 6a. The average last spring frost is April 17 and the first fall frost is October 26, giving you a growing season of approximately 192 days.

At an elevation of 324 feet, Northumberland County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Thyme during the growing season.

Northumberland County, PA (Zone 6a) Moderate season
192 days
Last Spring Frost April 17
192 growing days
First Fall Frost October 26

Northumberland County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 29 – Aug 31
Recommended (50%) ✓ Fits season (52 days to spare)
Transplant: Apr 24 🍅 Harvest: Jul 3 – Sep 4
Safe Start (90%) ✓ Fits season (44 days to spare)
Transplant: May 14 🍅 Harvest: Jul 23 – Sep 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.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~1,460 GDD — county provides 3,504 GDD Excellent fit

Thyme Planting Timeline โ€” Northumberland County, PA

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 24 Apr 24 โ€“ May 8
Harvest July 3 Jul 3 โ€“ Sep 4

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

70โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 6a

Growing Season

192 days

Growing Tips for Northumberland County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Thyme in Northumberland County, PA?

Northumberland County is in Zone 6a with an average last frost of April 17. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Northumberland County, PA?

Northumberland County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is April 17 and first fall frost is October 26.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Northumberland County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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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 Northumberland County, PA. Local conditions may vary. Last updated: April 2026.