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When to Plant Lemon Balm in Weld County, CO

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.

Weld County, Colorado is in USDA Zone 5a. The average last spring frost is May 2 and the first fall frost is October 7, giving you a growing season of approximately 158 days.

At an elevation of 6,992 feet, Weld County receives approximately 18.8 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Lemon Balm during the growing season. With low rainfall, drip irrigation is essential for growing Lemon Balm successfully. Mulch heavily to conserve soil moisture.

Weld County, CO (Zone 5a) Moderate season
158 days
Last Spring Frost May 2
158 growing days
First Fall Frost October 7

Weld County Soil Profile

Soil Type

Loam

Soil pH

6.6-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Transplant: May 4 🍅 Harvest: Jul 6 – Aug 24
Recommended (50%) ✓ Fits season (39 days to spare)
Transplant: May 9 🍅 Harvest: Jul 11 – Aug 29
Safe Start (90%) ✓ Fits season (34 days to spare)
Transplant: May 26 🍅 Harvest: Jul 28 – Sep 15

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
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 844 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Lemon Balm needs ~991 GDD — county provides 2,409 GDD Excellent fit

Lemon Balm Planting Timeline โ€” Weld County, CO

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors May 9 May 9 โ€“ May 23
Harvest July 11 Jul 11 โ€“ Aug 29

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June โ€”
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 5a

Growing Season

158 days

Growing Tips for Weld 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 Weld County, CO?

Weld County is in Zone 5a with an average last frost of May 2. Plan your Lemon Balm planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Weld County, CO?

Weld County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 2 and first fall frost is October 7.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Weld County gardeners in Zone 5a 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 Weld County, CO. Local conditions may vary. Last updated: April 2026.