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When to Plant Mizuna in Morton County, ND

Morton County, North Dakota Zone 4a May

Your May game plan for Morton County, North Dakota

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Morton County, North Dakota.

Avg. last frost May 14
Avg. first frost September 23
Soil temp (4") 55°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Transplant mizuna outside

    Your last frost (May 14) has passed. These warm-season crops can handle outdoor soil now.

  2. Put mizuna seeds straight in the ground

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Get ahead of June
  • Starting indoors: mizuna
  • First harvests: mizuna

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Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.

Morton County, North Dakota is in USDA Zone 4a. The average last spring frost is May 14 and the first fall frost is September 23, giving you a growing season of approximately 132 days.

At an elevation of 752 feet, Morton County receives approximately 33 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Mizuna to ensure they mature before fall.

Morton County, ND (Zone 4a) Short season
132 days
Last Spring Frost May 14
132 growing days
First Fall Frost September 23
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Morton County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (68 days to spare)
Start indoors: Mar 29 Transplant: May 10 🍅 Harvest: Jun 14 – Jul 12
Recommended (50%) ✓ Fits season (69 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jun 18 – Jul 16
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 22 Transplant: Jun 3 🍅 Harvest: Jul 8 – 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 Morton County

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

Soil pH

Your soil pH (6.3–7.6) overlaps with Mizuna's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.1%) — Mizuna will thrive.

How to Plant Mizuna

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 Mizuna

5
successive plantings in your 132-day season

Sow every 3.4 weeks. Last sowing by Aug 09 to harvest before frost.

For a dedicated fall crop, sow by Jul 01.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mizuna

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

Month Mizuna Needs Rainfall You Supplement Action
Jan 2.2" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 2.2" 2.1" 💧 Light watering
Jul 4.3" 2.8" 1.5" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.4" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Mizuna 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.

Mizuna needs ~375 GDD — county provides 1,320 GDD Excellent fit

Mizuna Planting Timeline — Morton County, ND

Mizuna Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 7 May 7 – May 28
Harvest June 18 Jun 18 – Jul 16
Fall Sowing July 1 Jul 1 – Jul 15

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 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 · Natural rainfall sufficient

📅 Days to Maturity

30–45 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

132 days in Morton County

Growing Tips for Mizuna in Morton County

Direct sow Mizuna outdoors after May 14 in Morton County when soil has warmed and frost danger has passed.

Your generous 132.0-day season in Morton County allows multiple plantings of Mizuna. Sow every 15.0 days for continuous harvest.

Common pests for Mizuna 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 spring or fall. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mizuna in Morton County, ND?

Morton County is in Zone 4a with an average last frost of May 14. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Morton County, ND?

Morton County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 14 and first fall frost is September 23.

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Your Morton County Garden Planner — Free

A 24-page printable planner built for Morton 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 Morton 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.