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When to Plant Mustard Greens in Moffat County, CO

Moffat County, Colorado Zone 5b May

May in Moffat County, Colorado — your action list

May is a pivotal month for Moffat County, Colorado gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost June 7
Avg. first frost September 14
Soil temp (4") 39°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
  1. Scatter mustard greens into prepared beds

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Before June arrives, get these ready
  • Transplants going out: mustard greens

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Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

Moffat County, Colorado is in USDA Zone 5b. The average last spring frost is June 7 and the first fall frost is September 14, giving you a growing season of approximately 99 days.

At an elevation of 6,597 feet, Moffat County receives approximately 12.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Mustard Greens during the growing season. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.

Moffat County, CO (Zone 5b) Very short season
99 days
Last Spring Frost June 7
99 growing days
First Fall Frost September 14
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Moffat County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Apr 23 Transplant: May 28 🍅 Harvest: Jul 2 – Sep 3
Recommended (50%) ✓ Fits season (1 days to spare)
Start indoors: May 3 Transplant: Jun 7 🍅 Harvest: Jul 12 – Sep 13
Safe Start (90%) ✓ Fits season (1 days to spare)
Start indoors: May 16 Transplant: Jun 20 🍅 Harvest: Jul 25 – Sep 26

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 Moffat County

How your county's soil matches Mustard Greens's growing requirements.

Soil pH

Your soil pH (6.8–8.3) is more alkaline than Mustard Greens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Moffat County is excellent for Mustard Greens — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Mustard Greens.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Mustard Greens.

How to Plant Mustard Greens

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Mustard Greens

3
successive plantings in your 99-day season

Sow every 3.4 weeks. Last sowing by Jul 26 to harvest before frost.

For a dedicated fall crop, sow by Jul 06.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.5″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 410 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mustard Greens

Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mustard Greens Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.2" 0" ❄️ Dormant
May 1.4" 0" ❄️ Dormant
Jun 3" 0.8" 2.2" 🚿 Regular watering
Jul 3" 1" 2" 🚿 Regular watering
Aug 3" 1.4" 1.6" 🚿 Regular watering
Sep 3" 1.1" 1.9" 🚿 Regular watering
Oct 1" 0" ❄️ Dormant
Nov 0.8" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Moffat County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Mustard Greens 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.

Mustard Greens needs ~580 GDD — county provides 1,435 GDD Excellent fit

Mustard Greens Planting Timeline — Moffat County, CO

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors May 3 May 3 – May 17
Transplant Outdoors June 7 Jun 7 – Jun 21
Direct Sow May 24 May 24 – Jun 14
Harvest July 12 Jul 12 – Sep 13
Fall Sowing July 6 Jul 6 – Jul 20

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · 1-2 times/week

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

99 days in Moffat County

Growing Tips for Mustard Greens in Moffat County

Direct sow Mustard Greens outdoors after June 07 in Moffat County when soil has warmed and frost danger has passed.

Common pests for Mustard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mustard Greens in Moffat County, CO?

Moffat County is in Zone 5b with an average last frost of June 7. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Moffat County, CO?

Moffat County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 7 and first fall frost is September 14.

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Your Moffat County Garden Planner — Free

A 24-page printable planner built for Moffat 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 Moffat County, CO. Local conditions may vary. Last updated: May 2026.

Sources & credits

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