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When to plant Cumin in Rangely, CO

The best window to plant Cumin in Rangely, is May 19–June 9, when soil warms to 50°F. Last frost typically hits June 2; first frost September 17. A second sowing from July 9 to July 23 extends the harvest into fall.

When to Plant Cumin in Rangely, CO

Rio Blanco County, Colorado Zone 5b June

What to do in June

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost June 2
Avg. first frost September 17
Soil temp (4") 48°F
Watering High
Pest pressure High
Daylight 14.8 hrs
A few tasks this June that'll pay off in July
  • Starting indoors: cumin
  • Fall sowing: cumin

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Cumin is a warm-season annual herb whose seeds are one of the most widely used spices globally. It requires a long, hot growing season of 3-4 months.

Rangely, 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 Cumin during the growing season. With low rainfall, drip irrigation is essential for growing Cumin successfully. Mulch heavily to conserve soil moisture.

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

Rangely Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Cumin Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 14 Transplant: May 12 🍅 Harvest: Aug 25 – Oct 27
Recommended (50%) ✗ May not fit
Start indoors: Apr 28 Transplant: May 26 🍅 Harvest: Sep 8 – Nov 10
Safe Start (90%) ✗ May not fit
Start indoors: May 16 Transplant: Jun 13 🍅 Harvest: Sep 26 – Nov 28

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 Rangely

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

Soil pH

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

Soil Texture

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

Organic Matter

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

How to Plant Cumin

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Cumin Water Budget

Plant needs
0.5″/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 Cumin

Cumin needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Cumin 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 2.2" 1.3" 0.9" 💧 Light watering
Jul 2.2" 1.4" 0.8" 💧 Light watering
Aug 2.2" 1.9" 0.3" 💧 Light watering
Sep 2.2" 1.6" 0.6" 💧 Light watering
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.

Cumin 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.

Cumin needs ~1,595 GDD — county provides 1,551 GDD Tight fit

Cumin Planting Timeline — Rangely, CO

Cumin Planting Calendar

Activity When Date Range
Start Indoors April 28 Apr 28 – May 12
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest September 8 Sep 8 – Nov 10
Fall Sowing July 9 Jul 9 – Jul 23

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing
August
September Harvest
October Harvest
November Harvest
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–8 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

107 days in Rio Blanco County

Growing Tips for Cumin in Rangely

Direct sow Cumin outdoors after June 02 in Rio Blanco County when soil has warmed and frost danger has passed.

Your 107.0-day growing season in Rio Blanco County is tight for Cumin (100.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Cumin in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

Rio Blanco County receives only 19" of rain annually. Cumin needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 4 weeks before last frost. Transplant after all danger of frost. Harvest when seed heads turn brown. Requires consistent warmth for proper seed development.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

When should I plant Cumin in Rangely, CO?

In Rangely, CO, plant Cumin 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 Rangely, CO for Cumin?

Rangely sits in USDA Zone 5b. Cumin grows reliably in zones 5a through 11b, so it's a good fit here.

Can Cumin grow in Rangely's climate?

Yes — Cumin grows well in Rangely's temperate climate. Rangely 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: June 2026.