When to plant Thyme in Iowa County, IA
Plant Thyme in Iowa County, between May 2 and May 16 — the only viable window. Zone 5b's short season (169 frost-free days) rules out a fall crop.
When to Plant Thyme in Iowa County, IA
What to do in June
Your Iowa County, Iowa garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.
A few tasks this June that'll pay off in July
- 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.
Iowa County, Iowa is in USDA Zone 5b. The average last spring frost is April 25 and the first fall frost is October 11, giving you a growing season of approximately 169 days.
At an elevation of 1,014 feet, Iowa County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Thyme during the growing season.
Iowa County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.3
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 Iowa County
How your county's soil matches Thyme's growing requirements.
Soil pH
Your soil pH (6.1–7.3) is within Thyme's preferred range (6.0–8.0).
Soil Texture
The silt loam soil in Iowa County is excellent for Thyme — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Thyme.
Organic Matter
Organic matter is excellent (4.7%) — Thyme will thrive.
How to Plant Thyme
Succession Planting Thyme
Sow every 8 weeks. Last sowing by Jul 13 to harvest before frost.
Thyme Water Budget
Water stress score is 6/10 — 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 | — | 1.9" | 0" | ❄️ Dormant |
| Feb | — | 1.7" | 0" | ❄️ Dormant |
| Mar | — | 3.1" | 0" | ❄️ Dormant |
| Apr | 1.3" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 5" | 0" | ✅ Rainfall sufficient |
| Jun | 1.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 4.2" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 3.6" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 3.5" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Iowa 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 — Iowa County, IA
Thyme Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Harvest | July 11 | Jul 11 – Sep 12 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
169 days in Iowa County
Growing Tips for Thyme in Iowa County
Direct sow Thyme outdoors after April 25 in Iowa 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 Iowa County, IA?
Iowa County is in Zone 5b with an average last frost of April 25. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iowa County, IA?
Iowa County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 25 and first fall frost is October 11.
When should I plant Thyme in Iowa County, IA?
In Iowa County, IA, plant Thyme after the last frost (around April 25) and before the first frost (around October 11). Best results when soil holds above 50°F.
What growing zone is Iowa County, IA for Thyme?
Iowa County sits in USDA Zone 5b. Thyme grows reliably in zones 4a through 9b, so it's a good fit here.
Can Thyme grow in Iowa County's climate?
Yes — Thyme grows well in Iowa County's temperate climate. Iowa County averages a 169-day frost-free season, with last frost around April 25 and first frost around October 11.
Your Iowa County Garden Planner — Free
A 22-page printable planner built for Iowa 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.