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When to Plant Komatsuna in Divide County, ND

Divide County, North Dakota Zone 4a May

Your May gardening checklist

Your garden in Divide County, North Dakota is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 15
Avg. first frost September 20
Soil temp (4") 52°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Set out komatsuna seedlings

    Your last frost (May 15) has passed. These warm-season crops can handle outdoor soil now.

  2. Outdoor sowing time: komatsuna

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

To set up a strong June, finish these tasks
  • Starting indoors: komatsuna
  • First harvests: komatsuna
  • Fall sowing: 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.

Divide County, North Dakota is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 20, giving you a growing season of approximately 128 days.

At an elevation of 994 feet, Divide County receives approximately 20.5 inches of rainfall annually with predominantly loam soil. Summer highs average 79°F, so choose short-season varieties of Komatsuna to ensure they mature before fall.

Divide County, ND (Zone 4a) Short season
128 days
Last Spring Frost May 15
128 growing days
First Fall Frost September 20
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Divide County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Jun 16 – Jul 21
Recommended (50%) ✓ Fits season (58 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jun 19 – Jul 24
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 15 Transplant: May 27 🍅 Harvest: Jul 1 – Aug 5

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 Divide County

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

Soil pH

Your soil pH (6.2–7.6) overlaps with Komatsuna's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Komatsuna.

How to Plant Komatsuna

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 Komatsuna

4
successive plantings in your 128-day season

Sow every 4 weeks. Last sowing by Aug 01 to harvest before frost.

For a dedicated fall crop, sow by Jun 28.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 447 gal / 100 sq ft
Drought risk

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

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 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 2.8" 1.5" 💧 Light watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 2.1" 2.2" 🚿 Regular watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Divide 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 ~393 GDD — county provides 1,184 GDD Excellent fit

Komatsuna Planting Timeline — Divide County, ND

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest June 19 Jun 19 – Jul 24
Fall Sowing June 28 Jun 28 – Jul 12

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Fall Sowing 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 · 1-2 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

128 days in Divide County

Growing Tips for Komatsuna in Divide County

Direct sow Komatsuna outdoors after May 15 in Divide County when soil has warmed and frost danger has passed.

Your generous 128.0-day season in Divide 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.

Divide County receives only 20" 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 Divide County, ND?

Divide County is in Zone 4a with an average last frost of May 15. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Divide County, ND?

Divide County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 20.

🌱

Your Divide County Garden Planner — Free

A 24-page printable planner built for Divide County (Zone 4a). 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 Divide County, ND. 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.