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When to Plant Lemon Balm in Monroe County, IL

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.

Monroe County, Illinois is in USDA Zone 6b. The average last spring frost is April 14 and the first fall frost is October 24, giving you a growing season of approximately 193 days.

At an elevation of 1,278 feet, Monroe County receives approximately 34.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Lemon Balm during the growing season.

Monroe County, IL (Zone 6b) Moderate season
193 days
Last Spring Frost April 14
193 growing days
First Fall Frost October 24

Monroe County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Transplant: Apr 13 🍅 Harvest: Jun 15 – Aug 3
Recommended (50%) ✓ Fits season (74 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 23 – Aug 11
Safe Start (90%) ✓ Fits season (76 days to spare)
Transplant: May 2 🍅 Harvest: Jul 4 – Aug 22

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 527 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Lemon Balm needs ~1,040 GDD — county provides 3,088 GDD Excellent fit

Lemon Balm Planting Timeline โ€” Monroe County, IL

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors April 21 Apr 21 โ€“ May 5
Harvest June 23 Jun 23 โ€“ Aug 11

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June Harvest
July Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“70 days

Soil pH

5.5 โ€“ 7.5

USDA Zone

Zone 6b

Growing Season

193 days

Growing Tips for Monroe County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Lemon Balm in Monroe County, IL?

Monroe County is in Zone 6b with an average last frost of April 14. Plan your Lemon Balm planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Monroe County, IL?

Monroe County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 14 and first fall frost is October 24.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Monroe County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

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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 Monroe County, IL. Local conditions may vary. Last updated: April 2026.