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When to Plant Mizuna in Ashland County, WI

Ashland County, Wisconsin Zone 3b April

What to do in April

We've pulled the most time-sensitive tasks for Ashland County, Wisconsin this April and put them front and centre. Tackle them in order.

Avg. last frost May 20
Avg. first frost September 27
Soil temp (4") 35°F
Watering None
Pest pressure Low
Daylight 13.3 hrs
May prep starts now
  • Transplants going out: mizuna
  • Direct-sowing: 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.

Ashland County, Wisconsin is in USDA Zone 3b. The average last spring frost is May 20 and the first fall frost is September 27, giving you a growing season of approximately 130 days.

At an elevation of 705 feet, Ashland County receives approximately 30.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Mizuna to ensure they mature before fall.

Ashland County, WI (Zone 3b) Short season
130 days
Last Spring Frost May 20
130 growing days
First Fall Frost September 27

Ashland County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (59 days to spare)
Start indoors: Apr 5 Transplant: May 17 🍅 Harvest: Jun 21 – Jul 19
Recommended (50%) ✓ Fits season (67 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jun 24 – Jul 22
Safe Start (90%) ✓ Fits season (65 days to spare)
Start indoors: Apr 23 Transplant: Jun 4 🍅 Harvest: Jul 9 – Aug 6

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 Ashland County

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

Soil pH

Your soil pH (6.0–7.0) is within Mizuna's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.9%) — 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 130-day season

Sow every 3.4 weeks. Last sowing by Aug 13 to harvest before frost.

For a dedicated fall crop, sow by Jul 05.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 9 gal / 100 sq ft

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 1.3" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 2.9" 1.4" 💧 Light watering
Aug 4.3" 3.6" 0.7" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 Light watering
Oct 2.7" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Ashland 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 ~347 GDD — county provides 1,202 GDD Excellent fit

Mizuna Planting Timeline — Ashland County, WI

Mizuna Planting Calendar

Activity When Date Range
Start Indoors April 8 Apr 8 – Apr 22
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 13 May 13 – Jun 3
Harvest June 24 Jun 24 – Jul 22
Fall Sowing July 5 Jul 5 – Jul 19

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 Transplant Outdoors Direct Sow Harvest
July Fall Sowing Harvest
August
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 3b

📆 Growing Season

130 days in Ashland County

Growing Tips for Mizuna in Ashland County

Direct sow Mizuna outdoors after May 20 in Ashland County when soil has warmed and frost danger has passed.

Your generous 130.0-day season in Ashland 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 Ashland County, WI?

Ashland County is in Zone 3b with an average last frost of May 20. Plan your Mizuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ashland County, WI?

Ashland County, Wisconsin is in USDA Hardiness Zone 3b. The average last spring frost is May 20 and first fall frost is September 27.

🌱

Your Ashland County Garden Planner — Free

A 24-page printable planner built for Ashland County (Zone 3b). 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 Ashland County, WI. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.