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When to Plant Daikon in Iron County, WI

Iron County, Wisconsin Zone 4a May

Your May game plan for Iron County, Wisconsin

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

Avg. last frost May 22
Avg. first frost September 25
Soil temp (4") 50°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Seed daikon outdoors

    Your soil is 50°F — warm enough for these to germinate without babying.

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Daikon is a large, mild Japanese radish that can grow over a foot long. It is excellent for pickling, stir-fries, and as a soil-breaking cover crop.

Iron County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 22 and the first fall frost is September 25, giving you a growing season of approximately 126 days.

At an elevation of 841 feet, Iron County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Daikon to ensure they mature before fall.

Iron County, WI (Zone 4a) Short season
126 days
Last Spring Frost May 22
126 growing days
First Fall Frost September 25

Iron County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Transplant: May 18 🍅 Harvest: Jul 13 – Aug 10
Recommended (50%) ✓ Fits season (42 days to spare)
Transplant: May 22 🍅 Harvest: Jul 17 – Aug 14
Safe Start (90%) ✓ Fits season (41 days to spare)
Transplant: Jun 6 🍅 Harvest: Aug 1 – Aug 29

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 Iron County

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

Soil pH

Your soil pH (5.7–6.9) overlaps with Daikon's range (5.8–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Daikon will thrive.

How to Plant Daikon

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 Daikon

2
successive plantings in your 126-day season

Sow every 5.7 weeks. Last sowing by Jul 17 to harvest before frost.

For a dedicated fall crop, sow by Jul 03.

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

Monthly Watering Guide for Daikon

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

Month Daikon Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 3.6" 0.7" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 2.5" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Daikon 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.

Daikon needs ~510 GDD — county provides 1,071 GDD Excellent fit

Daikon Planting Timeline — Iron County, WI

Daikon Planting Calendar

Activity When Date Range
Direct Sow May 15 May 15 – Jun 5
Harvest July 10 Jul 10 – Aug 7
Fall Sowing July 3 Jul 3 – Jul 17

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 5.8–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

126 days in Iron County

Growing Tips for Daikon in Iron County

Direct sow Daikon outdoors after May 22 in Iron County when soil has warmed and frost danger has passed.

Common pests for Daikon 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 late summer for fall harvest. Loosen soil deeply before planting. Thin seedlings to 6 inches apart. Harvest before hard freeze as exposed shoulders may crack.

Companion Planting

Good Companions

Avoid Planting Near

  • Hyssop

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Daikon in Iron County, WI?

Iron County is in Zone 4a with an average last frost of May 22. Plan your Daikon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Iron County, WI?

Iron County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 22 and first fall frost is September 25.

🌱

Your Iron County Garden Planner — Free

A 24-page printable planner built for Iron 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.

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 Iron County, WI. 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.