When to Plant Thyme in Snohomish County, WA
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.
Snohomish County, Washington is in USDA Zone 8a. The average last spring frost is March 25 and the first fall frost is November 2, giving you a growing season of approximately 222 days.
At an elevation of 230 feet, Snohomish County receives approximately 50.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Thyme during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Thyme root diseases.
Snohomish County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.8
Drainage
Well Drained
Plant Planting Risk Windows
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 Snohomish County
How your county's soil matches Thyme's growing requirements.
Soil pH
Your soil pH (5.7–6.8) overlaps with Thyme's range (6.0–8.0), though not a perfect match.
Soil Texture
The silt loam soil in Snohomish County is excellent for Thyme — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.4%) — Thyme will thrive.
How to Plant Thyme
Succession Planting Thyme
Sow every 8 weeks. Last sowing by Aug 04 to harvest before frost.
Plant Water Budget
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 | — | 7.7" | 0" | ❄️ Dormant |
| Feb | — | 5.6" | 0" | ❄️ Dormant |
| Mar | 1.3" | 5" | 0" | ✅ Rainfall sufficient |
| Apr | 1.3" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 2.6" | 0" | ✅ Rainfall sufficient |
| Jun | 1.3" | 1.6" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 0.7" | 0.6" | 💧 Light watering |
| Aug | 1.3" | 1" | 0.3" | 💧 Light watering |
| Sep | 1.3" | 2" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 4.2" | 0" | ✅ Rainfall sufficient |
| Nov | 1.3" | 8" | 0" | ✅ Rainfall sufficient |
| Dec | — | 8.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Snohomish 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 Planting Timeline — Snohomish County, WA
Thyme Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 1 | Apr 1 – Apr 15 |
| Harvest | June 10 | Jun 10 – Aug 12 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | — |
| 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: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
222 days in Snohomish County
Growing Tips for Thyme in Snohomish County
Direct sow Thyme outdoors after March 25 in Snohomish 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 →
Thyme in Other Locations
Frequently Asked Questions
When should I plant Thyme in Snohomish County, WA?
Snohomish County is in Zone 8a with an average last frost of March 25. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.
What planting zone is Snohomish County, WA?
Snohomish County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is March 25 and first fall frost is November 2.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Snohomish County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.
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