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When to Plant Komatsuna in St. Martin Parish, LA

St. Martin Parish, Louisiana Zone 9a May

May in St. Martin Parish, Louisiana — your action list

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

Avg. last frost February 13
Avg. first frost December 5
Soil temp (4") 75°F
Watering Moderate
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. Martin Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 13 and the first fall frost is December 5, giving you a growing season of approximately 295 days.

At an elevation of 417 feet, St. Martin Parish receives approximately 55.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°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. Martin Parish, LA (Zone 9a) Year-round
295 days
Last Spring Frost February 13
295 growing days
First Fall Frost December 5
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St. Martin Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

5.2-6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (229 days to spare)
Start indoors: Jan 3 Transplant: Jan 31 🍅 Harvest: Mar 7 – Apr 11
Recommended (50%) ✓ Fits season (225 days to spare)
Start indoors: Jan 16 Transplant: Feb 13 🍅 Harvest: Mar 20 – Apr 24
Safe Start (90%) ✓ Fits season (215 days to spare)
Start indoors: Feb 9 Transplant: Mar 9 🍅 Harvest: Apr 13 – May 18

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. Martin Parish

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

Soil pH

Your soil pH (5.2–6.0) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Komatsuna.

Organic Matter

Organic matter is moderate (2.3%). 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

10
successive plantings in your 295-day season

Sow every 4 weeks. Last sowing by Oct 16 to harvest before frost.

For a dedicated fall crop, sow by Oct 10.

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 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 5.1" 0" ❄️ Dormant
Feb 4.3" 4.4" 0" ✅ Rainfall sufficient
Mar 4.3" 5.7" 0" ✅ Rainfall sufficient
Apr 4.3" 3.8" 0.5" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 6.4" 0" ✅ Rainfall sufficient
Aug 4.3" 5.6" 0" ✅ Rainfall sufficient
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 4.3" 4.4" 0" ✅ Rainfall sufficient
Dec 4.3" 4.1" 0.2" 💧 Light watering

Water needs are for active growing months only (Feb–Dec in St. Martin 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 ~935 GDD — county provides 6,512 GDD Excellent fit

Komatsuna Planting Timeline — St. Martin Parish, LA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 – Jan 30
Transplant Outdoors February 13 Feb 13 – Feb 27
Direct Sow January 23 Jan 23 – Feb 13
Harvest March 20 Mar 20 – Apr 24
Fall Sowing October 10 Oct 10 – Oct 24

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

Month-by-Month Timeline

MonthActivities
January Start Indoors Direct Sow
February Transplant Outdoors Direct Sow
March 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 · Natural rainfall sufficient

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

295 days in St. Martin Parish

Growing Tips for Komatsuna in St. Martin Parish

Direct sow Komatsuna outdoors after February 13 in St. Martin Parish when soil has warmed and frost danger has passed.

Sandy soil in St. Martin 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 96°F in St. Martin Parish, provide afternoon shade for Komatsuna and water deeply in the morning.

Your generous 296.0-day season in St. Martin 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. Martin Parish, LA?

St. Martin Parish is in Zone 9a with an average last frost of February 13. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Martin Parish, LA?

St. Martin Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 13 and first fall frost is December 5.

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Your St. Martin Parish Garden Planner — Free

A 24-page printable planner built for St. Martin 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. Martin 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.