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When to Plant Mustard Greens in Sioux County, IA

Sioux County, Iowa Zone 4b April

April in the garden — Sioux County, Iowa

Your Sioux County, Iowa garden is entering a new phase. Here's what's on the schedule for April and why each task matters now.

Avg. last frost May 1
Avg. first frost October 3
Soil temp (4") 42°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
  1. Seed mustard greens outdoors

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Coming up in May — start thinking about
  • Transplants going out: mustard greens

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Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

Sioux County, Iowa is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 3, giving you a growing season of approximately 155 days.

At an elevation of 1,212 feet, Sioux County receives approximately 39.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Mustard Greens to ensure they mature before fall.

Sioux County, IA (Zone 4b) Moderate season
155 days
Last Spring Frost May 1
155 growing days
First Fall Frost October 3

Sioux County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 14 Transplant: Apr 25 🍅 Harvest: May 30 – Aug 1
Recommended (50%) ✓ Fits season (57 days to spare)
Start indoors: Mar 20 Transplant: May 1 🍅 Harvest: Jun 5 – Aug 7
Safe Start (90%) ✓ Fits season (54 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jun 19 – Aug 21

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 Sioux County

How your county's soil matches Mustard Greens's growing requirements.

Soil pH

Your soil pH (6.3–7.0) is within Mustard Greens's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — Mustard Greens will thrive.

How to Plant Mustard Greens

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 Mustard Greens

6
successive plantings in your 155-day season

Sow every 3.4 weeks. Last sowing by Aug 14 to harvest before frost.

For a dedicated fall crop, sow by Jul 11.

Plant Water Budget

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

Monthly Watering Guide for Mustard Greens

Mustard Greens needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Mustard Greens Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 4" 0" ❄️ Dormant
May 3" 4.8" 0" ✅ Rainfall sufficient
Jun 3" 4.4" 0" ✅ Rainfall sufficient
Jul 3" 4" 0" ✅ Rainfall sufficient
Aug 3" 3.9" 0" ✅ Rainfall sufficient
Sep 3" 3.8" 0" ✅ Rainfall sufficient
Oct 3" 3.3" 0" ✅ Rainfall sufficient
Nov 2.4" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Mustard Greens 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.

Mustard Greens needs ~490 GDD — county provides 1,898 GDD Excellent fit

Mustard Greens Planting Timeline — Sioux County, IA

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 1 May 1 – May 15
Direct Sow April 24 Apr 24 – May 15
Harvest June 5 Jun 5 – Aug 7
Fall Sowing July 11 Jul 11 – Jul 25

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

155 days in Sioux County

Growing Tips for Mustard Greens in Sioux County

Direct sow Mustard Greens outdoors after May 01 in Sioux County when soil has warmed and frost danger has passed.

Your generous 155.0-day season in Sioux County allows multiple plantings of Mustard Greens. Sow every 15.0 days for continuous harvest.

Common pests for Mustard Greens 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 early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mustard Greens in Sioux County, IA?

Sioux County is in Zone 4b with an average last frost of May 1. Plan your Mustard Greens planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sioux County, IA?

Sioux County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 3.

🌱

Your Sioux County Garden Planner — Free

A 24-page printable planner built for Sioux County (Zone 4b). 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 Sioux County, IA. 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.