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When to Plant Mustard Greens in Eagle County, CO

Eagle County, Colorado Zone 4b April

This month in Eagle County, Colorado

We've pulled the most time-sensitive tasks for Eagle County, Colorado this April and put them front and centre. Tackle them in order.

Avg. last frost June 16
Avg. first frost September 7
Soil temp (4") 21°F
Watering Moderate
Pest pressure Low
Daylight 13.1 hrs

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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.

Eagle County, Colorado is in USDA Zone 4b. The average last spring frost is June 16 and the first fall frost is September 7, giving you a growing season of approximately 83 days.

At an elevation of 7,116 feet, Eagle County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.

Eagle County, CO (Zone 4b) Very short season
83 days
Last Spring Frost June 16
83 growing days
First Fall Frost September 7

Eagle County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 24 Transplant: Jun 5 🍅 Harvest: Jul 10 – Sep 11
Recommended (50%) ✗ May not fit
Start indoors: May 5 Transplant: Jun 16 🍅 Harvest: Jul 21 – Sep 22
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: May 16 Transplant: Jun 27 🍅 Harvest: Aug 1 – Oct 3

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 Eagle County

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

Soil pH

Your soil pH (6.6–7.7) 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 Eagle County is excellent for Mustard Greens — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). 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 12 weeks before your first frost date for a fall harvest.

Succession Planting Mustard Greens

3
successive plantings in your 83-day season

Sow every 3.4 weeks. Last sowing by Jul 19 to harvest before frost.

For a dedicated fall crop, sow by Jun 15.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.8" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 3.2" 0" ❄️ Dormant
Jun 3" 1.6" 1.4" 💧 Light watering
Jul 3" 2.1" 0.9" 💧 Light watering
Aug 3" 2.4" 0.6" 💧 Light watering
Sep 3" 1.8" 1.2" 💧 Light watering
Oct 2" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Eagle 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 ~430 GDD — county provides 892 GDD Excellent fit

Mustard Greens Planting Timeline — Eagle County, CO

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors May 5 May 5 – May 19
Transplant Outdoors June 16 Jun 16 – Jun 30
Direct Sow June 9 Jun 9 – Jun 30
Harvest July 21 Jul 21 – Sep 22
Fall Sowing June 15 Jun 15 – Jun 29

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

83 days in Eagle County

Growing Tips for Mustard Greens in Eagle County

Direct sow Mustard Greens outdoors after June 16 in Eagle 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 Eagle County, CO?

Eagle County is in Zone 4b with an average last frost of June 16. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Eagle County, CO?

Eagle County, Colorado is in USDA Hardiness Zone 4b. The average last spring frost is June 16 and first fall frost is September 7.

🌱

Your Eagle County Garden Planner — Free

A 24-page printable planner built for Eagle County (Zone 4b). 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 Eagle County, CO. Local conditions may vary. Last updated: April 2026.

Sources & credits

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