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When to Plant Mitsuba in St. Charles Parish, LA

St. Charles Parish, Louisiana Zone 9a April

April in the garden — St. Charles Parish, Louisiana

If you only do a handful of things in the garden this April, make it these. They're sequenced around your zone's frost timing.

Avg. last frost February 20
Avg. first frost December 1
Soil temp (4") 68°F
Watering Low
Pest pressure High
Daylight 12.7 hrs
  1. Harvest mitsuba as they ripen

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

To set up a strong May, finish these tasks
  • 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.

St. Charles Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 20 and the first fall frost is December 1, giving you a growing season of approximately 284 days.

At an elevation of 154 feet, St. Charles Parish receives approximately 54.3 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 103°F, so Mitsuba may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Mitsuba will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Mitsuba root diseases.

St. Charles Parish, LA (Zone 9a) Year-round
284 days
Last Spring Frost February 20
284 growing days
First Fall Frost December 1
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St. Charles Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

4.9-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (183 days to spare)
Start indoors: Jan 9 Transplant: Jan 30 🍅 Harvest: Mar 27 – May 22
Recommended (50%) ✓ Fits season (179 days to spare)
Start indoors: Jan 23 Transplant: Feb 13 🍅 Harvest: Apr 10 – Jun 5
Safe Start (90%) ✓ Fits season (166 days to spare)
Start indoors: Feb 22 Transplant: Mar 15 🍅 Harvest: May 10 – Jul 5

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 St. Charles Parish

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

Soil pH

Your soil pH (4.9–6.3) is more acidic than Mitsuba prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in St. Charles Parish warms quickly in spring but drains fast. Mitsuba will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Mitsuba.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Mitsuba.

How to Plant Mitsuba

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Mitsuba

6
successive plantings in your 284-day season

Sow every 5.7 weeks. Last sowing by Sep 22 to harvest before frost.

For a dedicated fall crop, sow by Oct 06.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 4.3" 0" ❄️ Dormant
Feb 4.3" 4.8" 0" ✅ Rainfall sufficient
Mar 4.3" 4.9" 0" ✅ Rainfall sufficient
Apr 4.3" 4.2" 0.1" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.6" 0" ✅ Rainfall sufficient
Jul 4.3" 5.9" 0" ✅ Rainfall sufficient
Aug 4.3" 5" 0" ✅ Rainfall sufficient
Sep 4.3" 4.5" 0" ✅ Rainfall sufficient
Oct 4.3" 3" 1.3" 💧 Light watering
Nov 4.3" 4.3" 0" ✅ Rainfall sufficient
Dec 4.3" 4" 0.3" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in St. Charles Parish). 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 ~1,635 GDD — county provides 7,766 GDD Excellent fit

Mitsuba Planting Timeline — St. Charles Parish, LA

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors January 23 Jan 23 – Feb 6
Transplant Outdoors February 13 Feb 13 – Feb 27
Direct Sow January 30 Jan 30 – Feb 20
Harvest April 10 Apr 10 – Jun 5
Fall Sowing October 6 Oct 6 – Oct 20

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

284 days in St. Charles Parish

Growing Tips for Mitsuba in St. Charles Parish

Direct sow Mitsuba outdoors after February 20 in St. Charles Parish when soil has warmed and frost danger has passed.

Sandy soil in St. Charles Parish dries quickly — mulch Mitsuba with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 103°F in St. Charles Parish, provide afternoon shade for Mitsuba and water deeply in the morning.

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 St. Charles Parish, LA?

St. Charles Parish is in Zone 9a with an average last frost of February 20. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Charles Parish, LA?

St. Charles Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 20 and first fall frost is December 1.

🌱

Your St. Charles Parish Garden Planner — Free

A 24-page printable planner built for St. Charles Parish (Zone 9a). 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 St. Charles Parish, LA. 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.