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When to Plant Komatsuna in St. Landry Parish, LA

St. Landry Parish, Louisiana Zone 9a May

May to-do list for St. Landry Parish, Louisiana

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in St. Landry Parish, Louisiana.

Avg. last frost February 19
Avg. first frost December 1
Soil temp (4") 72°F
Watering Low
Pest pressure High
Daylight 13.5 hrs

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Komatsuna (Japanese mustard spinach) is a versatile Asian green with glossy, dark leaves and a mild, sweet flavor. It is extremely cold-hardy and heat-tolerant.

St. Landry Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 19 and the first fall frost is December 1, giving you a growing season of approximately 285 days.

At an elevation of 370 feet, St. Landry Parish receives approximately 59.8 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 97°F, so Komatsuna may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Komatsuna will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Komatsuna root diseases.

St. Landry Parish, LA (Zone 9a) Year-round
285 days
Last Spring Frost February 19
285 growing days
First Fall Frost December 1
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St. Landry Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

4.8-6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (216 days to spare)
Start indoors: Jan 10 Transplant: Feb 7 🍅 Harvest: Mar 14 – Apr 18
Recommended (50%) ✓ Fits season (215 days to spare)
Start indoors: Jan 22 Transplant: Feb 19 🍅 Harvest: Mar 26 – Apr 30
Safe Start (90%) ✓ Fits season (209 days to spare)
Start indoors: Feb 11 Transplant: Mar 11 🍅 Harvest: Apr 15 – May 20

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. Landry Parish

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

Soil pH

Your soil pH (4.8–6.0) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

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

How to Plant Komatsuna

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Komatsuna

9
successive plantings in your 285-day season

Sow every 4 weeks. Last sowing by Oct 12 to harvest before frost.

For a dedicated fall crop, sow by Oct 06.

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 310 gal / 100 sq ft

Monthly Watering Guide for Komatsuna

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

Month Komatsuna Needs Rainfall You Supplement Action
Jan 4.4" 0" ❄️ Dormant
Feb 4.3" 4.7" 0" ✅ Rainfall sufficient
Mar 4.3" 6" 0" ✅ Rainfall sufficient
Apr 4.3" 4.1" 0.2" 💧 Light watering
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 7" 0" ✅ Rainfall sufficient
Aug 4.3" 6.4" 0" ✅ Rainfall sufficient
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 4.3" 0" ✅ Rainfall sufficient
Nov 4.3" 4" 0.3" 💧 Light watering
Dec 4.3" 5.6" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in St. Landry Parish). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Komatsuna 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.

Komatsuna needs ~967 GDD — county provides 6,506 GDD Excellent fit

Komatsuna Planting Timeline — St. Landry Parish, LA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors January 22 Jan 22 – Feb 5
Transplant Outdoors February 19 Feb 19 – Mar 5
Direct Sow January 29 Jan 29 – Feb 19
Harvest March 26 Mar 26 – Apr 30
Fall Sowing October 6 Oct 6 – Oct 20

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

285 days in St. Landry Parish

Growing Tips for Komatsuna in St. Landry Parish

Direct sow Komatsuna outdoors after February 19 in St. Landry Parish when soil has warmed and frost danger has passed.

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

With summer highs reaching 97°F in St. Landry Parish, provide afternoon shade for Komatsuna and water deeply in the morning.

Your generous 286.0-day season in St. Landry Parish allows multiple plantings of Komatsuna. Sow every 17.0 days for continuous harvest.

Common pests for Komatsuna 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 spring or fall. One of the most forgiving Asian greens for all seasons. Harvest outer leaves or cut whole plants. Excellent for stir-fries, soups, or salads.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Komatsuna in St. Landry Parish, LA?

St. Landry Parish is in Zone 9a with an average last frost of February 19. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Landry Parish, LA?

St. Landry Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 19 and first fall frost is December 1.

🌱

Your St. Landry Parish Garden Planner — Free

A 24-page printable planner built for St. Landry 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. Landry Parish, LA. 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.