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When to Plant Mustard Greens in Okanogan County, WA

Okanogan County, Washington Zone 6b May

This month in Okanogan County, Washington

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

Avg. last frost May 13
Avg. first frost September 26
Soil temp (4") 49°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Get mustard greens in the ground

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

To set up a strong June, finish these tasks
  • Starting indoors: mustard greens
  • 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.

Okanogan County, Washington is in USDA Zone 6b. The average last spring frost is May 13 and the first fall frost is September 26, giving you a growing season of approximately 136 days.

At an elevation of 3,788 feet, Okanogan County receives approximately 21.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.

Okanogan County, WA (Zone 6b) Short season
136 days
Last Spring Frost May 13
136 growing days
First Fall Frost September 26

Okanogan County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (33 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jun 12 – Aug 14
Recommended (50%) ✓ Fits season (38 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Jun 17 – Aug 19
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: May 2 Transplant: Jun 6 🍅 Harvest: Jul 11 – Sep 12

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 Okanogan County

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

Soil pH

Your soil pH (5.4–6.5) is more acidic than Mustard Greens prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Okanogan 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 excellent (5.6%) — Mustard Greens will thrive.

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

5
successive plantings in your 136-day season

Sow every 3.4 weeks. Last sowing by Aug 07 to harvest before frost.

For a dedicated fall crop, sow by Jul 18.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 305 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 2.9" 0" ❄️ Dormant
Feb 2.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 3" 1.3" 1.7" 🚿 Regular watering
Jun 3" 0.7" 2.3" 🚿 Regular watering
Jul 3" 0.3" 2.7" 🚿 Regular watering
Aug 3" 0.4" 2.6" 🚿 Regular watering
Sep 3" 0.7" 2.3" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 3.6" 0" ❄️ Dormant
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Okanogan 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 ~490 GDD — county provides 1,666 GDD Excellent fit

Mustard Greens Planting Timeline — Okanogan County, WA

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 8 Apr 8 – Apr 22
Transplant Outdoors May 13 May 13 – May 27
Direct Sow April 29 Apr 29 – May 20
Harvest June 17 Jun 17 – Aug 19
Fall Sowing July 18 Jul 18 – Aug 1

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 6b

📆 Growing Season

136 days in Okanogan County

Growing Tips for Mustard Greens in Okanogan County

Direct sow Mustard Greens outdoors after May 13 in Okanogan County when soil has warmed and frost danger has passed.

Your generous 136.0-day season in Okanogan 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 Okanogan County, WA?

Okanogan County is in Zone 6b with an average last frost of May 13. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Okanogan County, WA?

Okanogan County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 13 and first fall frost is September 26.

🌱

Your Okanogan County Garden Planner — Free

A 24-page printable planner built for Okanogan County (Zone 6b). 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 Okanogan County, WA. 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.