When to plant Lobelia in Brown County, IL
Brown County sits in cold Zone 6a. Plant Lobelia April 3–April 17 for the single annual harvest; the October 16 first frost closes the window.
When to Plant Lobelia in Brown County, IL
June in Brown County, Illinois — your action list
Each item below is timed to Brown County, Illinois's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Begin indoor sowing: lobelia
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
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Collect lobelia at their peak
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
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.
Brown County, Illinois is in USDA Zone 6a. The average last spring frost is April 17 and the first fall frost is October 16, giving you a growing season of approximately 182 days.
At an elevation of 868 feet, Brown County receives approximately 36.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Lobelia during the growing season.
Brown County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.8
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 Brown County
How your county's soil matches Lobelia's growing requirements.
Soil pH
Your soil pH (6.3–6.8) is within Lobelia's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Brown County is excellent for Lobelia — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.2%) — Lobelia will thrive.
How to Plant Lobelia
Succession Planting Lobelia
Sow every 8 weeks. Last sowing by Jul 28 to harvest before frost.
Lobelia Water Budget
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| May | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Jun | 4.3" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Sep | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Oct | 4.3" | 2.5" | 1.8" | 💧 Light watering |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Brown 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 — Brown County, IL
Lobelia Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 13 | Feb 13 – Feb 27 |
| Transplant Outdoors | April 3 | Apr 3 – Apr 17 |
| Bloom | May 29 | May 29 – Aug 21 |
· 6" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | Bloom |
| 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: ideal
🗺️ USDA Zone
Zone 6a
📆 Growing Season
182 days in Brown County
Growing Tips for Lobelia in Brown County
Direct sow Lobelia outdoors after April 17 in Brown 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 Brown County, IL?
Brown County is in Zone 6a with an average last frost of April 17. Plan your Lobelia planting based on this frost date — see the calendar above for exact timing.
What planting zone is Brown County, IL?
Brown County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 17 and first fall frost is October 16.
When should I plant Lobelia in Brown County, IL?
In Brown County, IL, plant Lobelia after the last frost (around April 17) and before the first frost (around October 16). Best results when soil holds above 50°F.
What growing zone is Brown County, IL for Lobelia?
Brown County sits in USDA Zone 6a. Lobelia grows reliably in zones 3a through 9b, so it's a good fit here.
Can Lobelia grow in Brown County's climate?
Yes — Lobelia grows well in Brown County's temperate climate. Brown County averages a 182-day frost-free season, with last frost around April 17 and first frost around October 16.
Your Brown County Garden Planner — Free
A 22-page printable planner built for Brown County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.