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When to Plant Komatsuna in St. John the Baptist Parish, LA

St. John the Baptist Parish, Louisiana Zone 9b May

Your May planting checklist for St. John the Baptist Parish, Louisiana

May is a pivotal month for St. John the Baptist Parish, Louisiana gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost February 20
Avg. first frost December 1
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Bring in the komatsuna

    If you can't use it all right away, check the food-preservation section of your planner.

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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. John the Baptist Parish, Louisiana is in USDA Zone 9b. 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 309 feet, St. John the Baptist Parish receives approximately 53.7 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 103°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. John the Baptist Parish, LA (Zone 9b) Year-round
284 days
Last Spring Frost February 20
284 growing days
First Fall Frost December 1

St. John the Baptist Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

4.8-6.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (218 days to spare)
Start indoors: Jan 9 Transplant: Feb 6 🍅 Harvest: Mar 13 – Apr 17
Recommended (50%) ✓ Fits season (214 days to spare)
Start indoors: Jan 23 Transplant: Feb 20 🍅 Harvest: Mar 27 – May 1
Safe Start (90%) ✓ Fits season (201 days to spare)
Start indoors: Feb 22 Transplant: Mar 22 🍅 Harvest: Apr 26 – May 31

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. John the Baptist Parish

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

Soil pH

Your soil pH (4.8–6.1) is more acidic than Komatsuna prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in St. John the Baptist 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 (2.1%). 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 284-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
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

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" 0" ❄️ Dormant
Feb 4.3" 4" 0.3" 💧 Light watering
Mar 4.3" 4.6" 0" ✅ Rainfall sufficient
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 4.7" 0" ✅ Rainfall sufficient
Jun 4.3" 5" 0" ✅ Rainfall sufficient
Jul 4.3" 6.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.7" 0" ✅ Rainfall sufficient
Sep 4.3" 4.3" 0" ✅ Rainfall sufficient
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 4.3" 3.5" 0.8" 💧 Light watering
Dec 4.3" 4.8" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in St. John the Baptist 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 ~1,158 GDD — county provides 7,766 GDD Excellent fit

Komatsuna Planting Timeline — St. John the Baptist Parish, LA

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors January 23 Jan 23 – Feb 6
Transplant Outdoors February 20 Feb 20 – Mar 6
Direct Sow January 30 Jan 30 – Feb 20
Harvest March 27 Mar 27 – May 1
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 Harvest
June
July
August
September
October Fall Sowing
November
December

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 9b

📆 Growing Season

284 days in St. John the Baptist Parish

Growing Tips for Komatsuna in St. John the Baptist Parish

Direct sow Komatsuna outdoors after February 20 in St. John the Baptist Parish when soil has warmed and frost danger has passed.

Sandy soil in St. John the Baptist 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 103°F in St. John the Baptist Parish, provide afternoon shade for Komatsuna and water deeply in the morning.

Your generous 285.0-day season in St. John the Baptist 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. John the Baptist Parish, LA?

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

What planting zone is St. John the Baptist Parish, LA?

St. John the Baptist Parish, Louisiana is in USDA Hardiness Zone 9b. The average last spring frost is February 20 and first fall frost is December 1.

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Your St. John the Baptist Parish Garden Planner — Free

A 24-page printable planner built for St. John the Baptist Parish (Zone 9b). 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. John the Baptist 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.