When to plant Thyme in Jefferson County, MT
Plant Thyme in Jefferson County, between June 22 and July 6 — the only viable window. Zone 5a's short season (84 frost-free days) rules out a fall crop.
When to Plant Thyme in Jefferson County, MT
July in the garden — Jefferson County, Montana
A quick July briefing for Jefferson County, Montana gardeners — what's urgent, what's next, and what can wait.
Before August arrives, get these ready
- First harvests: thyme
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.
Jefferson County, Montana is in USDA Zone 5a. The average last spring frost is June 15 and the first fall frost is September 7, giving you a growing season of approximately 84 days.
At an elevation of 7,214 feet, Jefferson County receives approximately 21.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Thyme to ensure they mature before fall.
Jefferson County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.9
Drainage
Well Drained
Thyme 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 Jefferson County
How your county's soil matches Thyme's growing requirements.
Soil pH
Your soil pH (6.4–7.9) is within Thyme's preferred range (6.0–8.0).
Soil Texture
The loam soil in Jefferson County is excellent for Thyme — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Thyme.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Thyme.
How to Plant Thyme
Thyme Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 2" | 0" | ❄️ Dormant |
| May | — | 2.5" | 0" | ❄️ Dormant |
| Jun | 1.3" | 1.5" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 2" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 2" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 2" | 0" | ✅ Rainfall sufficient |
| Oct | — | 1.8" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Jefferson 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 — Jefferson County, MT
Thyme Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | June 22 | Jun 22 – Jul 6 |
| Harvest | August 31 | Aug 31 – Nov 2 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | Transplant Outdoors |
| July | Transplant Outdoors |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| 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: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
84 days in Jefferson County
Growing Tips for Thyme in Jefferson County
Direct sow Thyme outdoors after June 15 in Jefferson County when soil has warmed and frost danger has passed.
Your 84.0-day growing season in Jefferson County is tight for Thyme (70.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.
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 Jefferson County, MT?
Jefferson County is in Zone 5a with an average last frost of June 15. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jefferson County, MT?
Jefferson County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 15 and first fall frost is September 7.
When should I plant Thyme in Jefferson County, MT?
In Jefferson County, MT, plant Thyme after the last frost (around June 15) and before the first frost (around September 7). Best results when soil holds above 50°F.
What growing zone is Jefferson County, MT for Thyme?
Jefferson County sits in USDA Zone 5a. Thyme grows reliably in zones 4a through 9b, so it's a good fit here.
Can Thyme grow in Jefferson County's climate?
Yes — Thyme grows well in Jefferson County's temperate climate. Jefferson County averages a 84-day frost-free season, with last frost around June 15 and first frost around September 7.
Your Jefferson County Garden Planner — Free
A 22-page printable planner built for Jefferson County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.