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When to Plant Komatsuna in Pend Oreille County, WA

Pend Oreille County, Washington Zone 6a May

This month in Pend Oreille County, Washington

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

Avg. last frost May 10
Avg. first frost September 23
Soil temp (4") 48°F
Watering Critical
Pest pressure Low
Daylight 15 hrs
  1. Set out komatsuna seedlings

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

Before June arrives, get these ready
  • Starting indoors: komatsuna
  • First harvests: komatsuna

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Komatsuna (Japanese mustard spinach) is a versatile Asian green with glossy, dark leaves and a mild, sweet flavor. It is extremely cold-hardy and heat-tolerant.

Pend Oreille County, Washington is in USDA Zone 6a. The average last spring frost is May 10 and the first fall frost is September 23, giving you a growing season of approximately 136 days.

At an elevation of 3,807 feet, Pend Oreille County receives approximately 13.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Komatsuna during the growing season. With low rainfall, drip irrigation is essential for growing Komatsuna successfully. Mulch heavily to conserve soil moisture.

Pend Oreille County, WA (Zone 6a) Short season
136 days
Last Spring Frost May 10
136 growing days
First Fall Frost September 23
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Pend Oreille County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (67 days to spare)
Start indoors: Mar 27 Transplant: May 1 🍅 Harvest: Jun 5 – Jul 10
Recommended (50%) ✓ Fits season (66 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jun 14 – Jul 19
Safe Start (90%) ✓ Fits season (64 days to spare)
Start indoors: Apr 26 Transplant: May 31 🍅 Harvest: Jul 5 – Aug 9

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 Pend Oreille County

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

Soil pH

Your soil pH (5.3–6.6) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Pend Oreille County is excellent for Komatsuna — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Komatsuna.

Organic Matter

Organic matter is excellent (5.0%) — Komatsuna will thrive.

How to Plant Komatsuna

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 Komatsuna

4
successive plantings in your 136-day season

Sow every 4 weeks. Last sowing by Aug 04 to harvest before frost.

For a dedicated fall crop, sow by Jul 15.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,080 gal / 100 sq ft

Monthly Watering Guide for Komatsuna

Komatsuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Komatsuna Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 0.9" 0" ❄️ Dormant
May 4.3" 0.8" 3.5" 🚿 Regular watering
Jun 4.3" 0.5" 3.8" 🚿 Regular watering
Jul 4.3" 0.2" 4.1" 🚿 Regular watering
Aug 4.3" 0.2" 4.1" 🚿 Regular watering
Sep 4.3" 0.6" 3.7" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 2.1" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Komatsuna 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.

Komatsuna needs ~616 GDD — county provides 1,972 GDD Excellent fit

Komatsuna Planting Timeline — Pend Oreille County, WA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow April 26 Apr 26 – May 17
Harvest June 14 Jun 14 – Jul 19
Fall Sowing July 15 Jul 15 – Jul 29

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
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

136 days in Pend Oreille County

Growing Tips for Komatsuna in Pend Oreille County

Direct sow Komatsuna outdoors after May 10 in Pend Oreille County when soil has warmed and frost danger has passed.

Your generous 136.0-day season in Pend Oreille County allows multiple plantings of Komatsuna. Sow every 17.0 days for continuous harvest.

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

Pend Oreille County receives only 13" of rain annually. Komatsuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. One of the most forgiving Asian greens for all seasons. Harvest outer leaves or cut whole plants. Excellent for stir-fries, soups, or salads.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Komatsuna in Pend Oreille County, WA?

Pend Oreille County is in Zone 6a with an average last frost of May 10. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pend Oreille County, WA?

Pend Oreille County, Washington is in USDA Hardiness Zone 6a. The average last spring frost is May 10 and first fall frost is September 23.

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Your Pend Oreille County Garden Planner — Free

A 24-page printable planner built for Pend Oreille County (Zone 6a). 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 Pend Oreille 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.