When to Plant Lemon Balm in Cass County, IA
Your May planting checklist for Cass County, Iowa
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Cass County, Iowa.
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Move lemon balm into the garden
Your last frost (April 25) has passed. These warm-season crops can handle outdoor soil now.
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.
Cass County, Iowa is in USDA Zone 5b. The average last spring frost is April 25 and the first fall frost is October 9, giving you a growing season of approximately 167 days.
At an elevation of 1,043 feet, Cass County receives approximately 31.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Lemon Balm during the growing season.
Cass County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-6.7
Drainage
Well Drained
Plant Planting Risk Windows
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 Lemon Balm's growing requirements.
Soil pH
Your soil pH (6.2–6.7) is within Lemon Balm's preferred range (5.5–7.5).
Soil Texture
The silt loam soil in Cass County is excellent for Lemon Balm — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.4%) — Lemon Balm will thrive.
How to Plant Lemon Balm
Succession Planting Lemon Balm
Sow every 6.9 weeks. Last sowing by Jul 31 to harvest before frost.
Plant Water Budget
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.1" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Cass 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 Planting Timeline — Cass County, IA
Lemon Balm Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 2 | May 2 – May 16 |
| Harvest | July 4 | Jul 4 – Aug 22 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–70 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
167 days in Cass County
Growing Tips for Lemon Balm in Cass County
Direct sow Lemon Balm outdoors after April 25 in Cass 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 →
Lemon Balm in Other Locations
Frequently Asked Questions
When should I plant Lemon Balm in Cass County, IA?
Cass County is in Zone 5b with an average last frost of April 25. Plan your Lemon Balm planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cass County, IA?
Cass County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 25 and first fall frost is October 9.
Your Cass County Garden Planner — Free
A 24-page printable planner built for Cass County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.