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When to Plant Bee Balm in Cass County, MN

Cass County, Minnesota Zone 4a May

This month in Cass County, Minnesota

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 12
Avg. first frost September 28
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 14.9 hrs
  1. Get bee balm in the ground

    Frost risk is low now in Cass County, Minnesota. If you've been covering beds overnight, you can stop.

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Bee balm is a native perennial herb with shaggy, scarlet flower heads that attract hummingbirds, bees, and butterflies. Its leaves make an aromatic tea reminiscent of Earl Grey.

Cass County, Minnesota is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is September 28, giving you a growing season of approximately 139 days.

At an elevation of 938 feet, Cass County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Bee Balm to ensure they mature before fall.

Cass County, MN (Zone 4a) Short season
139 days
Last Spring Frost May 12
139 growing days
First Fall Frost September 28
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Cass County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 15 🍅 Harvest: Aug 14 – Oct 9
Recommended (50%) ✗ May not fit
Transplant: May 19 🍅 Harvest: Aug 18 – Oct 13
Safe Start (90%) ✗ May not fit
Transplant: Jun 3 🍅 Harvest: Sep 2 – Oct 28

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 Cass County

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

Soil pH

Your soil pH (5.9–6.9) overlaps with Bee Balm's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Bee Balm will thrive.

How to Plant Bee Balm

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 26 gal / 100 sq ft

Monthly Watering Guide for Bee Balm

Bee Balm needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Bee Balm Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 3" 0" ❄️ Dormant
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 3.9" 0.4" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 2.5" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Cass County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Bee 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.

Bee Balm needs ~1,050 GDD — county provides 1,390 GDD Excellent fit

Bee Balm Planting Timeline — Cass County, MN

Bee Balm Planting Calendar

Activity When Date Range
Transplant Outdoors May 19 May 19 – Jun 2
Harvest August 18 Aug 18 – Oct 13

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
August Harvest
September Harvest
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

139 days in Cass County

Growing Tips for Bee Balm in Cass County

Direct sow Bee Balm outdoors after May 12 in Cass County when soil has warmed and frost danger has passed.

General growing tips

Start from seed, divisions, or transplants. Provide good air circulation to prevent powdery mildew. Deadhead spent flowers for reblooming. Divide clumps every 3 years.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Bee Balm in Cass County, MN?

Cass County is in Zone 4a with an average last frost of May 12. Plan your Bee Balm planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cass County, MN?

Cass County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is September 28.

🌱

Your Cass County Garden Planner — Free

A 24-page printable planner built for Cass County (Zone 4a). 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 Cass County, MN. 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.