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When to Plant Bee Balm in Black Hawk County, IA

Black Hawk County, Iowa Zone 5a May

May to-do list for Black Hawk County, Iowa

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 April 29
Avg. first frost October 7
Soil temp (4") 55°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Time to transplant bee balm

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

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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.

Black Hawk County, Iowa is in USDA Zone 5a. The average last spring frost is April 29 and the first fall frost is October 7, giving you a growing season of approximately 161 days.

At an elevation of 1,380 feet, Black Hawk County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Bee Balm to ensure they mature before fall.

Black Hawk County, IA (Zone 5a) Moderate season
161 days
Last Spring Frost April 29
161 growing days
First Fall Frost October 7
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Black Hawk County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Apr 30 🍅 Harvest: Jul 30 – Oct 15
Recommended (50%) ✗ May not fit
Transplant: May 6 🍅 Harvest: Aug 5 – Oct 21
Safe Start (90%) ✗ May not fit
Transplant: May 20 🍅 Harvest: Aug 19 – Nov 4

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 Black Hawk County

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

Soil pH

Your soil pH (6.2–7.1) overlaps with Bee Balm's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — 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
Watering frequency Only during dry spells
Season total 1 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.7" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 5" 0" ✅ Rainfall sufficient
Jun 4.3" 5.3" 0" ✅ Rainfall sufficient
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Black Hawk 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 ~1,365 GDD — county provides 2,093 GDD Excellent fit

Bee Balm Planting Timeline — Black Hawk County, IA

Bee Balm Planting Calendar

Activity When Date Range
Transplant Outdoors May 6 May 6 – May 20
Harvest August 5 Aug 5 – Oct 21

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June
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 5a

📆 Growing Season

161 days in Black Hawk County

Growing Tips for Bee Balm in Black Hawk County

Direct sow Bee Balm outdoors after April 29 in Black Hawk 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 Black Hawk County, IA?

Black Hawk County is in Zone 5a with an average last frost of April 29. Plan your Bee Balm planting based on this frost date — see the calendar above for exact timing.

What planting zone is Black Hawk County, IA?

Black Hawk County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 29 and first fall frost is October 7.

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Your Black Hawk County Garden Planner — Free

A 24-page printable planner built for Black Hawk County (Zone 5a). 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 Black Hawk County, IA. 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.