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When to Plant Mizuna in Fall River County, SD

Fall River County, South Dakota Zone 5a May

May to-do list for Fall River County, South Dakota

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 14
Avg. first frost October 1
Soil temp (4") 54°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
  1. Set out mizuna seedlings

    Frost risk is low now in Fall River County, South Dakota. If you've been covering beds overnight, you can stop.

June prep starts now
  • 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.

Fall River County, South Dakota is in USDA Zone 5a. The average last spring frost is May 14 and the first fall frost is October 1, giving you a growing season of approximately 140 days.

At an elevation of 1,056 feet, Fall River County receives approximately 25.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Mizuna to ensure they mature before fall.

Fall River County, SD (Zone 5a) Short season
140 days
Last Spring Frost May 14
140 growing days
First Fall Frost October 1

Fall River County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (69 days to spare)
Start indoors: Apr 6 Transplant: May 11 🍅 Harvest: Jun 15 – Jul 13
Recommended (50%) ✓ Fits season (77 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jun 18 – Jul 16
Safe Start (90%) ✓ Fits season (75 days to spare)
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Jun 30 – Jul 28

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 Fall River County

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

Soil pH

Your soil pH (6.5–7.2) is within Mizuna's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.6%). Annual compost additions will help Mizuna.

How to Plant Mizuna

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 Mizuna

5
successive plantings in your 140-day season

Sow every 3.4 weeks. Last sowing by Aug 17 to harvest before frost.

For a dedicated fall crop, sow by Jul 23.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 356 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 1.8" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 2.8" 1.5" 💧 Light watering
Jun 4.3" 1.8" 2.5" 🚿 Regular watering
Jul 4.3" 2" 2.3" 🚿 Regular watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 Light watering
Oct 4.3" 2.2" 2.1" 💧 Light watering
Nov 1.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Fall River 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 ~488 GDD — county provides 1,820 GDD Excellent fit

Mizuna Planting Timeline — Fall River County, SD

Mizuna Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 14 May 14 – May 28
Direct Sow April 30 Apr 30 – May 21
Harvest June 18 Jun 18 – Jul 16
Fall Sowing July 23 Jul 23 – Aug 6

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
September
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

30–45 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

140 days in Fall River County

Growing Tips for Mizuna in Fall River County

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

Your generous 140.0-day season in Fall River 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 Fall River County, SD?

Fall River County is in Zone 5a 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 Fall River County, SD?

Fall River County, South Dakota is in USDA Hardiness Zone 5a. The average last spring frost is May 14 and first fall frost is October 1.

🌱

Your Fall River County Garden Planner — Free

A 24-page printable planner built for Fall River County (Zone 5a). 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 Fall River County, SD. Local conditions may vary. Last updated: May 2026.

Sources & credits

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