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When to plant Mitsuba in Davis County, IA

Davis County gardeners should plant Mitsuba between April 5 and April 26 in spring. With Davis County's Zone 5b climate (last frost April 19), Mitsuba needs 50–70 days to mature — plant by August 7 for a full harvest. A second sowing from August 7 to August 21 extends the harvest into fall.

When to Plant Mitsuba in Davis County, IA

Davis County, Iowa Zone 5b August

Top priorities for Davis County, Iowa gardeners in August

August is a pivotal month for Davis County, Iowa gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 19
Avg. first frost October 16
Soil temp (4") 76°F
Watering High
Pest pressure High
Daylight 13.6 hrs
  1. Basket week: mitsuba

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

  2. Start your fall crops: mitsuba

    Count back from your first frost (October 16) — these need to mature before the cold arrives.

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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.

Davis County, Iowa is in USDA Zone 5b. The average last spring frost is April 19 and the first fall frost is October 16, giving you a growing season of approximately 180 days.

At an elevation of 859 feet, Davis County receives approximately 30.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Mitsuba during the growing season.

Davis County, IA (Zone 5b) Moderate season
180 days
Last Spring Frost April 19
180 growing days
First Fall Frost October 16

Davis County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.7

Drainage

Well Drained

Mitsuba Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Start indoors: Mar 9 Transplant: Apr 6 🍅 Harvest: Jun 1 – Jul 27
Recommended (50%) ✓ Fits season (75 days to spare)
Start indoors: Mar 15 Transplant: Apr 12 🍅 Harvest: Jun 7 – Aug 2
Safe Start (90%) ✓ Fits season (73 days to spare)
Start indoors: Mar 29 Transplant: Apr 26 🍅 Harvest: Jun 21 – Aug 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.

Soil Compatibility in Davis County

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

Soil pH

Your soil pH (6.2–6.7) is within Mitsuba's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — 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

4
successive plantings in your 180-day season

Sow every 5.7 weeks. Last sowing by Aug 07 to harvest before frost.

For a dedicated fall crop, sow by Aug 07.

Mitsuba Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 469 gal / 100 sq ft

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 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 2.9" 1.4" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 2.6" 1.7" 💧 Light watering
Sep 4.3" 2.3" 2" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Davis 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 2,475 GDD Excellent fit

Mitsuba Planting Timeline — Davis County, IA

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 – Mar 29
Transplant Outdoors April 12 Apr 12 – Apr 26
Direct Sow April 5 Apr 5 – Apr 26
Harvest June 7 Jun 7 – Aug 2
Fall Sowing August 7 Aug 7 – Aug 21

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

180 days in Davis County

Growing Tips for Mitsuba in Davis County

Direct sow Mitsuba outdoors after April 19 in Davis 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 Davis County, IA?

Davis County is in Zone 5b with an average last frost of April 19. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is Davis County, IA?

Davis County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 19 and first fall frost is October 16.

When should I plant Mitsuba in Davis County, IA?

In Davis County, IA, plant Mitsuba after the last frost (around April 19) and before the first frost (around October 16). Best results when soil holds above 50°F.

What growing zone is Davis County, IA for Mitsuba?

Davis County sits in USDA Zone 5b. Mitsuba grows reliably in zones 4a through 9b, so it's a good fit here.

Can Mitsuba grow in Davis County's climate?

Yes — Mitsuba grows well in Davis County's temperate climate. Davis County averages a 180-day frost-free season, with last frost around April 19 and first frost around October 16.

🌱

Your Davis County Garden Planner — Free

A 22-page printable planner built for Davis County (Zone 5b). 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 Davis County, IA. Local conditions may vary. Last updated: August 2026.

Sources & credits

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