When to Plant Lobelia in Utah

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.

Utah spans USDA hardiness zones 5a, 5b, 6a, 6b, 7a, 7b, 8b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

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Click your county for exact Lobelia planting dates based on your local frost dates.

Hover over a county to see details. Click to view planting guide.

Lobelia Planting Calendar for Utah

▸ Zone 5a ~166 day growing season · Full guide →

Last frost: April 25 · First frost: October 8 · 166 day season

Activity	When	Date Range
Start Indoors	February 14	Feb 14 – Feb 28
Transplant Outdoors	April 18	Apr 18 – May 2
Bloom	June 13	Jun 13 – Aug 22

▸ Zone 5b ~178 day growing season · Full guide →

Last frost: April 18 · First frost: October 13 · 178 day season

Activity	When	Date Range
Start Indoors	February 7	Feb 7 – Feb 21
Transplant Outdoors	April 11	Apr 11 – Apr 25
Bloom	June 6	Jun 6 – Aug 22

▸ Zone 6a ~193 day growing season · Full guide →

Last frost: April 10 · First frost: October 20 · 193 day season

Activity	When	Date Range
Start Indoors	February 6	Feb 6 – Feb 20
Transplant Outdoors	March 27	Mar 27 – Apr 10
Bloom	May 22	May 22 – Aug 14

▸ Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

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

▸ Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity	When	Date Range
Start Indoors	January 21	Jan 21 – Feb 4
Transplant Outdoors	March 4	Mar 4 – Mar 18
Bloom	April 29	Apr 29 – Jul 22

▸ Zone 7b ~235 day growing season · Full guide →

Last frost: March 18 · First frost: November 8 · 235 day season

Activity	When	Date Range
Start Indoors	January 14	Jan 14 – Jan 28
Transplant Outdoors	February 18	Feb 18 – Mar 4
Bloom	April 15	Apr 15 – Jun 24

▸ Zone 8b ~276 day growing season · Full guide →

Last frost: February 25 · First frost: November 28 · 276 day season

Activity	When	Date Range
Start Indoors	December 31	Dec 31 – Jan 14
Transplant Outdoors	January 14	Jan 14 – Jan 28
Bloom	March 11	Mar 11 – Apr 22

Growing Tips for Utah

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.

Lobelia in Other States

Frequently Asked Questions

When should I plant Lobelia in Utah?

Planting dates for Lobelia in Utah depend on your USDA zone. Utah spans zones 5a, 5b, 6a, 6b, 7a, 7b, 8b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Utah for planting?

Utah contains USDA hardiness zones 5a, 5b, 6a, 6b, 7a, 7b, 8b. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.

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