When to Plant Lobelia in USDA Zone 6b
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.
In Zone 6b, the average last spring frost is around April 3 and the first fall frost is around October 25, giving you a growing season of approximately 205 days.
Lobelia Planting Timeline — Zone 6b
Where Is USDA Zone 6b?
The map below highlights the states that contain Zone 6b. Click any state to see the Lobelia planting schedule for that location.
Lobelia Planting Calendar — Zone 6b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 30 | Jan 30 – Feb 13 |
| Transplant Outdoors | March 20 | Mar 20 – Apr 3 |
| Bloom | May 15 | May 15 – Aug 7 |
· 6" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors |
| March | Transplant Outdoors |
| April | Transplant Outdoors |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | — |
Free Zone 6b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 6b with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Partial Shade (3-6 hours)
💧 Water
Moderate — regular watering
Days to Maturity
70–80 days
Soil pH
6 – 7
Zone Temperature Range
-5°F to 0°F average annual minimum
Growing Season
205 days (Zone 6b average)
Planting Specifications
| Plant Spacing | 6 inches apart |
| Row Spacing | 8 inches between rows |
Succession Planting Lobelia in Zone 6b
Sow every 8 weeks for continuous harvest throughout the season.
Growing Tips for Lobelia in Zone 6b
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
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Saving Lobelia Seeds
Recommended for Your Garden
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
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Related Plants
Lobelia in Other Zones
Lobelia by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Lobelia in Zone 6b?
In Zone 6b, plan your Lobelia planting around the average last frost date of April 3. Start seeds indoors around January 30. Transplant seedlings around March 20.
Can Lobelia grow in Zone 6b?
Yes, Lobelia can grow well in Zone 6b, hardy in USDA zones 3a through 9b. Zone 6b has a growing season of approximately 205 days, which is sufficient for Lobelia (70-80 days to maturity).
When can I harvest Lobelia in Zone 6b?
In Zone 6b, expect to harvest Lobelia from May 15 – August 7. Lobelia takes 70-80 days from planting to harvest.
What is the last frost date for Zone 6b?
The average last spring frost in Zone 6b is around April 3, and the first fall frost is around October 25. This gives a growing season of approximately 205 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Lobelia?
Good companion plants for Lobelia include Petunias, Sweet Alyssum, Begonias, Impatiens. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 6b Garden Planner — Free
A 22-page printable planner tailored to Zone 6b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.