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When to Plant Lemon Balm in Glacier County, MT

Glacier County, Montana Zone 4b May

May to-do list for Glacier County, Montana

May is a pivotal month for Glacier County, Montana gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 22
Avg. first frost September 18
Soil temp (4") 30°F
Watering High
Pest pressure Low
Daylight 15 hrs
  1. Time to transplant lemon balm

    Your last frost (May 22) has passed. These warm-season crops can handle outdoor soil now.

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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.

Glacier County, Montana is in USDA Zone 4b. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 8,147 feet, Glacier County receives approximately 13.3 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Lemon Balm to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Lemon Balm successfully. Mulch heavily to conserve soil moisture.

Glacier County, MT (Zone 4b) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18
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Glacier County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (0 days to spare)
Transplant: May 22 🍅 Harvest: Jul 24 – Sep 11
Recommended (50%) ✓ Fits season (0 days to spare)
Transplant: May 29 🍅 Harvest: Jul 31 – Sep 18
Safe Start (90%) ✗ May not fit
Transplant: Jun 18 🍅 Harvest: Aug 20 – Oct 8

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 Glacier County

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

Soil pH

Your soil pH (6.3–8.1) overlaps with Lemon Balm's range (5.5–7.5), though not a perfect match.

Soil Texture

The loam soil in Glacier County is excellent for Lemon Balm — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). 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

2
successive plantings in your 119-day season

Sow every 6.9 weeks. Last sowing by Jul 10 to harvest before frost.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.5″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 39 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 2.2" 1.6" 0.6" 💧 Light watering
Jun 2.2" 1" 1.2" 🚿 Regular watering
Jul 2.2" 1.3" 0.9" 💧 Light watering
Aug 2.2" 1.4" 0.8" 💧 Light watering
Sep 2.2" 1.1" 1.1" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Glacier County). 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 ~650 GDD — county provides 1,190 GDD Excellent fit

Lemon Balm Planting Timeline — Glacier County, MT

Lemon Balm Planting Calendar

Activity When Date Range
Transplant Outdoors May 29 May 29 – Jun 12
Harvest July 31 Jul 31 – Sep 18

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.5"/week · Only during dry spells

📅 Days to Maturity

60–70 days

🧪 Soil pH

Needs 5.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

119 days in Glacier County

Growing Tips for Lemon Balm in Glacier County

Direct sow Lemon Balm outdoors after May 22 in Glacier County when soil has warmed and frost danger has passed.

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 Glacier County, MT?

Glacier County is in Zone 4b with an average last frost of May 22. Plan your Lemon Balm planting based on this frost date — see the calendar above for exact timing.

What planting zone is Glacier County, MT?

Glacier County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 22 and first fall frost is September 18.

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Your Glacier County Garden Planner — Free

A 24-page printable planner built for Glacier County (Zone 4b). 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 Glacier County, MT. 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.