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When to plant Thyme in Rio Blanco County, CO

Plant Thyme in Rio Blanco County during the brief June 9–June 23 window. With 107 frost-free days, fall plantings can't mature before September 17.

When to Plant Thyme in Rio Blanco County, CO

Thyme
Rio Blanco County, Colorado Zone 5b July

Rio Blanco County, Colorado gardeners: here's your July plan

Welcome to July in Zone 5b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost June 2
Avg. first frost September 17
Soil temp (4") 54°F
Watering High
Pest pressure High
Daylight 14.6 hrs
Coming up in August — start thinking about
  • First harvests: 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.

Rio Blanco County, Colorado is in USDA Zone 5b. The average last spring frost is June 2 and the first fall frost is September 17, giving you a growing season of approximately 107 days.

At an elevation of 6,974 feet, Rio Blanco County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Thyme during the growing season. With low rainfall, drip irrigation is essential for growing Thyme successfully. Mulch heavily to conserve soil moisture.

Rio Blanco County, CO (Zone 5b) Short season
107 days
Last Spring Frost June 2
107 growing days
First Fall Frost September 17

Rio Blanco County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Thyme Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 26 🍅 Harvest: Aug 4 – Oct 6
Recommended (50%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Aug 18 – Oct 20
Safe Start (90%) ✗ May not fit
Transplant: Jun 27 🍅 Harvest: Sep 5 – Nov 7

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 Rio Blanco County

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

Soil pH

Your soil pH (6.4–7.7) is within Thyme's preferred range (6.0–8.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Thyme.

How to Plant Thyme

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

Thyme Water Budget

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

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 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 2.1" 0" ❄️ Dormant
Jun 1.3" 1.3" 0" ✅ Rainfall sufficient
Jul 1.3" 1.4" 0" ✅ Rainfall sufficient
Aug 1.3" 1.9" 0" ✅ Rainfall sufficient
Sep 1.3" 1.6" 0" ✅ Rainfall sufficient
Oct 1.6" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Rio Blanco 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 ~1,160 GDD — county provides 1,551 GDD Excellent fit

Thyme Planting Timeline — Rio Blanco County, CO

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors June 9 Jun 9 – Jun 23
Harvest August 18 Aug 18 – Oct 20

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

Month-by-Month Timeline

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

107 days in Rio Blanco County

Growing Tips for Thyme in Rio Blanco County

Direct sow Thyme outdoors after June 02 in Rio Blanco 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 Rio Blanco County, CO?

Rio Blanco County is in Zone 5b with an average last frost of June 2. Plan your Thyme planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rio Blanco County, CO?

Rio Blanco County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 2 and first fall frost is September 17.

When should I plant Thyme in Rio Blanco County, CO?

In Rio Blanco County, CO, plant Thyme after the last frost (around June 2) and before the first frost (around September 17). Best results when soil holds above 50°F.

What growing zone is Rio Blanco County, CO for Thyme?

Rio Blanco 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 Rio Blanco County's climate?

Yes — Thyme grows well in Rio Blanco County's temperate climate. Rio Blanco County averages a 107-day frost-free season, with last frost around June 2 and first frost around September 17.

🌱

Your Rio Blanco County Garden Planner — Free

A 22-page printable planner built for Rio Blanco 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.

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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 Rio Blanco County, CO. Local conditions may vary. Last updated: July 2026.

Sources & credits

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