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When to Plant Mizuna in Palo Alto County, IA

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.

Palo Alto County, Iowa is in USDA Zone 4b. The average last spring frost is April 27 and the first fall frost is October 8, giving you a growing season of approximately 164 days.

At an elevation of 1,358 feet, Palo Alto County receives approximately 34.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Mizuna to ensure they mature before fall.

Palo Alto County, IA (Zone 4b) Moderate season
164 days
Last Spring Frost April 27
164 growing days
First Fall Frost October 8

Palo Alto County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (102 days to spare)
Start indoors: Mar 10 Transplant: Apr 21 🍅 Harvest: May 26 – Jun 23
Recommended (50%) ✓ Fits season (101 days to spare)
Start indoors: Mar 16 Transplant: Apr 27 🍅 Harvest: Jun 1 – Jun 29
Safe Start (90%) ✓ Fits season (102 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jun 18 – Jul 16

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 195 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Mizuna needs ~403 GDD — county provides 1,763 GDD Excellent fit

Mizuna Planting Timeline โ€” Palo Alto County, IA

Mizuna Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 โ€“ Mar 30
Transplant Outdoors April 27 Apr 27 โ€“ May 11
Direct Sow April 20 Apr 20 โ€“ May 11
Fall Sowing July 16 Jul 16 โ€“ Jul 30
Harvest June 1 Jun 1 โ€“ Jun 29

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

30โ€“45 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4b

Growing Season

164 days

Growing Tips for Palo Alto County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Mizuna in Palo Alto County, IA?

Palo Alto County is in Zone 4b with an average last frost of April 27. Plan your Mizuna planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Palo Alto County, IA?

Palo Alto County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 27 and first fall frost is October 8.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Palo Alto County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

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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 Palo Alto County, IA. Local conditions may vary. Last updated: April 2026.