When to Plant Larkspur in Illinois
Larkspur (Consolida ajacis) is a cool-season annual that produces tall, delicate spires of blue, purple, pink, and white flowers reminiscent of its perennial cousin, delphinium. Direct-sown into cold soil or fall-sown in mild-winter climates, it blooms in spring before going to seed as summer heat arrives. An excellent cut flower and cottage-garden staple.
Illinois spans USDA hardiness zones 5a, 5b, 6a, 6b, 7a (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 Larkspur planting dates based on your local frost dates.
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Larkspur Planting Calendar for Illinois
▸ Zone 5a ~166 day growing season · Full guide →
Last frost: April 25 · First frost: October 8 · 166 day season
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 28 | Mar 28 – Apr 18 |
| Bloom | June 6 | Jun 6 – Aug 1 |
▸ Zone 5b ~178 day growing season · Full guide →
Last frost: April 18 · First frost: October 13 · 178 day season
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 21 | Mar 21 – Apr 11 |
| Bloom | May 30 | May 30 – Jul 25 |
▸ Zone 6a ~193 day growing season · Full guide →
Last frost: April 10 · First frost: October 20 · 193 day season
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 13 | Mar 13 – Apr 3 |
| Bloom | May 22 | May 22 – Jul 17 |
▸ Zone 6b ~205 day growing season · Full guide →
Last frost: April 3 · First frost: October 25 · 205 day season
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | March 6 | Mar 6 – Mar 27 |
| Bloom | May 15 | May 15 – Jul 10 |
▸ Zone 7a ~221 day growing season · Full guide →
Last frost: March 25 · First frost: November 1 · 221 day season
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | February 25 | Feb 25 – Mar 18 |
| Bloom | May 6 | May 6 – Jul 15 |
| Fall Sowing | August 23 | Aug 23 – Sep 6 |
Growing Tips for Illinois
Larkspur does not transplant well — direct-sow only. In cold climates (zones 2–6), sow directly in early spring as soon as soil can be worked, 4–6 weeks before last frost; cold soil improves germination. In zones 7–10, fall-sow 8–10 weeks before first frost for spring bloom. Press seeds lightly into soil; they need darkness to germinate — cover with 1/8–1/4 inch of soil. Thin to 6–12 inches to prevent powdery mildew. Allow seed pods to mature and self-sow for naturalized colonies. All parts are toxic if ingested.
Larkspur in Other States
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- 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 Larkspur in Illinois?
Planting dates for Larkspur in Illinois depend on your USDA zone. Illinois spans zones 5a, 5b, 6a, 6b, 7a. Check the planting calendar above for your specific zone's frost dates and planting windows.
What zone is Illinois for planting?
Illinois contains USDA hardiness zones 5a, 5b, 6a, 6b, 7a. 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.