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When to Plant Lemon Balm in St. Tammany Parish, LA

St. Tammany Parish, Louisiana Zone 9a May

May in the garden — St. Tammany Parish, Louisiana

May is a pivotal month for St. Tammany 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 November 23
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. It's harvest week for lemon balm

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

Before June arrives, get these ready
  • First harvests: lemon balm

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Lemon balm is a vigorous perennial herb with bright green, lemon-scented leaves. It makes a refreshing tea and is easy to grow but can spread aggressively.

St. Tammany Parish, Louisiana is in USDA Zone 9a. The average last spring frost is February 20 and the first fall frost is November 23, giving you a growing season of approximately 276 days.

At an elevation of 321 feet, St. Tammany Parish receives approximately 57.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 96°F, so Lemon Balm may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Lemon Balm will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Lemon Balm root diseases.

St. Tammany Parish, LA (Zone 9a) Year-round
276 days
Last Spring Frost February 20
276 growing days
First Fall Frost November 23
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St. Tammany 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 (170 days to spare)
Transplant: Feb 6 🍅 Harvest: Apr 10 – May 29
Recommended (50%) ✓ Fits season (157 days to spare)
Transplant: Feb 27 🍅 Harvest: May 1 – Jun 19
Safe Start (90%) ✓ Fits season (144 days to spare)
Transplant: Apr 6 🍅 Harvest: Jun 8 – Jul 27

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. Tammany Parish

How your county's soil matches Lemon Balm's growing requirements.

Soil pH

Your soil pH (4.8–6.1) is more acidic than Lemon Balm prefers (5.5–7.5). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Lemon Balm.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Lemon Balm.

How to Plant Lemon Balm

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

Succession Planting Lemon Balm

5
successive plantings in your 276-day season

Sow every 6.9 weeks. Last sowing by Sep 14 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Lemon Balm

Lemon Balm needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Lemon Balm Needs Rainfall You Supplement Action
Jan 4.5" 0" ❄️ Dormant
Feb 2.2" 4.5" 0" ✅ Rainfall sufficient
Mar 2.2" 5.8" 0" ✅ Rainfall sufficient
Apr 2.2" 4.2" 0" ✅ Rainfall sufficient
May 2.2" 5.2" 0" ✅ Rainfall sufficient
Jun 2.2" 4.6" 0" ✅ Rainfall sufficient
Jul 2.2" 6.8" 0" ✅ Rainfall sufficient
Aug 2.2" 5.3" 0" ✅ Rainfall sufficient
Sep 2.2" 4.2" 0" ✅ Rainfall sufficient
Oct 2.2" 4.1" 0" ✅ Rainfall sufficient
Nov 2.2" 4.3" 0" ✅ Rainfall sufficient
Dec 4.3" 0" ❄️ Dormant

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

Lemon Balm 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.

Lemon Balm needs ~1,430 GDD — county provides 6,094 GDD Excellent fit

Lemon Balm Planting Timeline — St. Tammany Parish, LA

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors February 27 Feb 27 – Mar 13
Harvest May 1 May 1 – Jun 19

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

Month-by-Month Timeline

MonthActivities
January
February Transplant Outdoors
March Transplant Outdoors
April
May Harvest
June Harvest
July
August
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

276 days in St. Tammany Parish

Growing Tips for Lemon Balm in St. Tammany Parish

Direct sow Lemon Balm outdoors after February 20 in St. Tammany Parish when soil has warmed and frost danger has passed.

Sandy soil in St. Tammany Parish dries quickly — mulch Lemon Balm 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. Tammany Parish, provide afternoon shade for Lemon Balm and water deeply in the morning.

With 58" of annual rainfall in St. Tammany Parish, ensure good drainage for Lemon Balm — excess moisture can promote root rot and fungal diseases.

General growing tips

Start from seed, cuttings, or divisions. Contain in pots or use barriers to prevent spreading. Harvest frequently to keep plants bushy and prevent flowering.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Lemon Balm in St. Tammany Parish, LA?

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

What planting zone is St. Tammany Parish, LA?

St. Tammany Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is February 20 and first fall frost is November 23.

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Your St. Tammany Parish Garden Planner — Free

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