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When to Plant Mustard Greens in Coos County, OR

Coos County, Oregon Zone 9a May

Your May gardening checklist

A quick May briefing for Coos County, Oregon gardeners — what's urgent, what's next, and what can wait.

Avg. last frost March 22
Avg. first frost November 19
Soil temp (4") 71°F
Watering High
Pest pressure High
Daylight 14.5 hrs
  1. Bring in the mustard greens

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Get ahead of June
  • First harvests: 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.

Coos County, Oregon is in USDA Zone 9a. The average last spring frost is March 22 and the first fall frost is November 19, giving you a growing season of approximately 242 days.

At an elevation of 96 feet, Coos County receives approximately 38.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Mustard Greens during the growing season.

Coos County, OR (Zone 9a) Long season
242 days
Last Spring Frost March 22
242 growing days
First Fall Frost November 19

Coos County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (141 days to spare)
Start indoors: Feb 7 Transplant: Mar 7 🍅 Harvest: Apr 11 – Jun 13
Recommended (50%) ✓ Fits season (144 days to spare)
Start indoors: Feb 22 Transplant: Mar 22 🍅 Harvest: Apr 26 – Jun 28
Safe Start (90%) ✓ Fits season (139 days to spare)
Start indoors: Mar 25 Transplant: Apr 22 🍅 Harvest: May 27 – Jul 29

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 Coos County

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

Soil pH

Your soil pH (5.4–6.8) overlaps with Mustard Greens's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.7%) — Mustard Greens will thrive.

How to Plant Mustard Greens

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Mustard Greens

9
successive plantings in your 242-day season

Sow every 3.4 weeks. Last sowing by Sep 30 to harvest before frost.

For a dedicated fall crop, sow by Sep 24.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 57 gal / 100 sq ft

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 5.5" 0" ❄️ Dormant
Feb 4.5" 0" ❄️ Dormant
Mar 3" 4.4" 0" ✅ Rainfall sufficient
Apr 3" 3.1" 0" ✅ Rainfall sufficient
May 3" 2.3" 0.7" 💧 Light watering
Jun 3" 1.6" 1.4" 💧 Light watering
Jul 3" 0.6" 2.4" 🚿 Regular watering
Aug 3" 0.8" 2.2" 🚿 Regular watering
Sep 3" 1.4" 1.6" 🚿 Regular watering
Oct 3" 3.3" 0" ✅ Rainfall sufficient
Nov 3" 5.9" 0" ✅ Rainfall sufficient
Dec 5.5" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Coos 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 ~670 GDD — county provides 4,053 GDD Excellent fit

Mustard Greens Planting Timeline — Coos County, OR

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 – Mar 8
Transplant Outdoors March 22 Mar 22 – Apr 5
Direct Sow March 1 Mar 1 – Mar 22
Harvest April 26 Apr 26 – Jun 28
Fall Sowing September 24 Sep 24 – Oct 8

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

242 days in Coos County

Growing Tips for Mustard Greens in Coos County

Direct sow Mustard Greens outdoors after March 22 in Coos County when soil has warmed and frost danger has passed.

Your generous 242.0-day season in Coos County allows multiple plantings of Mustard Greens. Sow every 15.0 days for continuous harvest.

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 Coos County, OR?

Coos County is in Zone 9a with an average last frost of March 22. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Coos County, OR?

Coos County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is March 22 and first fall frost is November 19.

🌱

Your Coos County Garden Planner — Free

A 24-page printable planner built for Coos County (Zone 9a). 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 Coos County, OR. 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.