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When to Plant Mizuna in Seward County, KS

Seward County, Kansas Zone 6b May

What to do in May

Here's what deserves your attention in Seward County, Kansas this month. Everything below is tailored to Zone 6b and timed around your local frost dates.

Avg. last frost April 18
Avg. first frost October 18
Soil temp (4") 65°F
Watering Moderate
Pest pressure Low
Daylight 14 hrs
  1. Fire up the seed-starting tray: mizuna

    Your window is short. These crops want several weeks of indoor growth before they go outside.

  2. Pick mizuna

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Looking ahead to June
  • 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.

Seward County, Kansas is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 18, giving you a growing season of approximately 183 days.

At an elevation of 860 feet, Seward County receives approximately 24.1 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Mizuna during the growing season.

Seward County, KS (Zone 6b) Moderate season
183 days
Last Spring Frost April 18
183 growing days
First Fall Frost October 18

Seward 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 (121 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: May 18 – Jun 15
Recommended (50%) ✓ Fits season (120 days to spare)
Start indoors: Mar 14 Transplant: Apr 18 🍅 Harvest: May 23 – Jun 20
Safe Start (90%) ✓ Fits season (120 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jun 7 – Jul 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 Seward 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 Seward County is excellent for Mizuna — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.4%). 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

7
successive plantings in your 183-day season

Sow every 3.4 weeks. Last sowing by Sep 03 to harvest before frost.

For a dedicated fall crop, sow by Aug 09.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 873 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 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 4.3" 2.6" 1.7" 💧 Light watering
May 4.3" 3" 1.3" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 1.9" 2.4" 🚿 Regular watering
Aug 4.3" 2.5" 1.8" 💧 Light watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 1.7" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Seward 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 ~628 GDD — county provides 3,065 GDD Excellent fit

Mizuna Planting Timeline — Seward County, KS

Mizuna Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors April 18 Apr 18 – May 2
Direct Sow April 4 Apr 4 – Apr 25
Harvest May 23 May 23 – Jun 20
Fall Sowing August 9 Aug 9 – Aug 23

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

30–45 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

183 days in Seward County

Growing Tips for Mizuna in Seward County

Direct sow Mizuna outdoors after April 18 in Seward County when soil has warmed and frost danger has passed.

Your generous 183.0-day season in Seward 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.

Seward County receives only 24" of rain annually. Mizuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Seward County, KS?

Seward County is in Zone 6b with an average last frost of April 18. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Seward County, KS?

Seward County, Kansas is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 18.

🌱

Your Seward County Garden Planner — Free

A 24-page printable planner built for Seward 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Seward County, KS. 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.