When to Plant Lobelia in Madison County, OH
This month in Madison County, Ohio
A quick June briefing for Madison County, Ohio gardeners — what's urgent, what's next, and what can wait.
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Get lobelia seeds going inside
You're about 15 weeks out from your last frost — the perfect window to get these germinating indoors.
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It's harvest week for lobelia
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
Coming up in July — start thinking about
- First harvests: lobelia
Lobelia (Lobelia erinus) is a cool-season annual prized for the intense cobalt blue that is rare among bedding flowers. It blooms most prolifically in spring and early summer but stalls or dies back during heat peaks above 90°F. In zones 3–7 it delivers a long display; in zones 8–9 it is best treated as a spring annual that fades by midsummer. Trailing types cascade beautifully from containers and window boxes.
Madison County, Ohio is in USDA Zone 6b. The average last spring frost is April 22 and the first fall frost is October 20, giving you a growing season of approximately 181 days.
At an elevation of 674 feet, Madison County receives approximately 35.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Lobelia during the growing season.
Madison County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.1
Drainage
Well Drained
Lobelia 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 Madison County
How your county's soil matches Lobelia's growing requirements.
Soil pH
Your soil pH (5.8–7.1) overlaps with Lobelia's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Madison County is excellent for Lobelia — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.2%) — Lobelia will thrive.
How to Plant Lobelia
Succession Planting Lobelia
Sow every 8 weeks. Last sowing by Aug 01 to harvest before frost.
Lobelia Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Lobelia
Lobelia needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Lobelia Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.3" | 1" | 💧 Light watering |
| May | 4.3" | 3.8" | 0.5" | 💧 Light watering |
| Jun | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Sep | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Oct | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 1.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Madison County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Lobelia 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.
Lobelia Planting Timeline — Madison County, OH
Lobelia Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 18 | Feb 18 – Mar 4 |
| Transplant Outdoors | April 8 | Apr 8 – Apr 22 |
| Bloom | June 3 | Jun 3 – Aug 26 |
· 6" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1"/week · Only during dry spells
📅 Days to Maturity
70–80 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 6b
📆 Growing Season
181 days in Madison County
Growing Tips for Lobelia in Madison County
Direct sow Lobelia outdoors after April 22 in Madison County when soil has warmed and frost danger has passed.
General growing tips
Start seeds indoors 10–12 weeks before last frost — seed is dust-fine and requires light to germinate; surface-sow and press gently. Keep at 65–70°F. Not reliably direct-sown. Transplant in cool weather, 2–4 weeks before last frost date is acceptable in zones 5+. Shear plants by one-third after the first bloom flush to encourage a second flush in fall. Provide afternoon shade in zones 7+ to extend bloom into summer.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Lobelia in Other Locations
Frequently Asked Questions
When should I plant Lobelia in Madison County, OH?
Madison County is in Zone 6b with an average last frost of April 22. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.
What planting zone is Madison County, OH?
Madison County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 22 and first fall frost is October 20.
Your Madison County Garden Planner — Free
A 22-page printable planner built for Madison County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.