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When to Plant Mitsuba in Tama County, IA

Tama County, Iowa Zone 5a May

May in the garden — Tama County, Iowa

We've pulled the most time-sensitive tasks for Tama County, Iowa this May and put them front and centre. Tackle them in order.

Avg. last frost April 28
Avg. first frost October 8
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
Coming up in June — start thinking about
  • Starting indoors: mitsuba
  • First harvests: mitsuba

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Mitsuba (Japanese parsley) is a shade-loving herb with trefoil leaves and a mild celery-parsley flavor. It is essential in Japanese cuisine for soups, salads, and garnishes.

Tama County, Iowa is in USDA Zone 5a. The average last spring frost is April 28 and the first fall frost is October 8, giving you a growing season of approximately 163 days.

At an elevation of 1,268 feet, Tama County receives approximately 38.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Mitsuba during the growing season.

Tama County, IA (Zone 5a) Moderate season
163 days
Last Spring Frost April 28
163 growing days
First Fall Frost October 8

Tama County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (59 days to spare)
Start indoors: Mar 18 Transplant: Apr 15 🍅 Harvest: Jun 10 – Aug 5
Recommended (50%) ✓ Fits season (58 days to spare)
Start indoors: Mar 24 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 11
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Apr 7 Transplant: May 5 🍅 Harvest: Jun 30 – Aug 25

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 Tama County

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

Soil pH

Your soil pH (5.8–6.9) overlaps with Mitsuba's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Mitsuba.

Organic Matter

Organic matter is excellent (5.1%) — Mitsuba will thrive.

How to Plant Mitsuba

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Mitsuba

3
successive plantings in your 163-day season

Sow every 5.7 weeks. Last sowing by Jul 30 to harvest before frost.

For a dedicated fall crop, sow by Jul 30.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 527 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mitsuba

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

Month Mitsuba Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 3" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

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

Mitsuba 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.

Mitsuba needs ~825 GDD — county provides 2,241 GDD Excellent fit

Mitsuba Planting Timeline — Tama County, IA

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 – Apr 7
Transplant Outdoors April 21 Apr 21 – May 5
Direct Sow April 14 Apr 14 – May 5
Harvest June 16 Jun 16 – Aug 11
Fall Sowing July 30 Jul 30 – Aug 13

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

163 days in Tama County

Growing Tips for Mitsuba in Tama County

Direct sow Mitsuba outdoors after April 28 in Tama County when soil has warmed and frost danger has passed.

Common pests for Mitsuba in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow or start indoors in partial shade. Mitsuba prefers cool, moist conditions. Harvest outer stems as needed. Self-sows readily in shaded garden areas.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mitsuba in Tama County, IA?

Tama County is in Zone 5a with an average last frost of April 28. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is Tama County, IA?

Tama County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 28 and first fall frost is October 8.

🌱

Your Tama County Garden Planner — Free

A 24-page printable planner built for Tama County (Zone 5a). 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 Tama County, IA. 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.