When to Plant Bachelor's Button in Colorado

Bachelor's Button (Centaurea cyanus), also called cornflower, is a carefree cool-season annual best known for its vivid cobalt-blue flowers — one of the truest blues in the annual garden. It tolerates light frosts, self-seeds prolifically, and thrives in poor to average soils. A traditional cut flower and pollinator magnet, it has been cultivated in gardens for centuries.

Colorado spans USDA hardiness zones 4b, 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 Bachelor's Button planting dates based on your local frost dates.

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Bachelor's Button Planting Calendar for Colorado

▸ Zone 4b ~155 day growing season · Full guide →

Last frost: May 1 · First frost: October 3 · 155 day season

Activity	When	Date Range
Start Indoors	March 13	Mar 13 – Mar 27
Transplant Outdoors	May 1	May 1 – May 15
Direct Sow	April 17	Apr 17 – May 8
Bloom	July 3	Jul 3 – Sep 4

▸ 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	March 14	Mar 14 – Mar 28
Transplant Outdoors	April 25	Apr 25 – May 9
Direct Sow	April 4	Apr 4 – Apr 25
Bloom	June 27	Jun 27 – Sep 5

▸ 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	March 7	Mar 7 – Mar 21
Transplant Outdoors	April 18	Apr 18 – May 2
Direct Sow	March 28	Mar 28 – Apr 18
Bloom	June 20	Jun 20 – Sep 5

▸ 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 27	Feb 27 – Mar 13
Transplant Outdoors	April 10	Apr 10 – Apr 24
Direct Sow	March 13	Mar 13 – Apr 3
Bloom	June 12	Jun 12 – Aug 28
Fall Sowing	September 8	Sep 8 – Sep 22

▸ 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	February 20	Feb 20 – Mar 6
Transplant Outdoors	April 3	Apr 3 – Apr 17
Direct Sow	March 6	Mar 6 – Mar 27
Bloom	June 5	Jun 5 – Aug 28
Fall Sowing	September 13	Sep 13 – Sep 27

▸ 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	February 11	Feb 11 – Feb 25
Transplant Outdoors	March 25	Mar 25 – Apr 8
Direct Sow	February 18	Feb 18 – Mar 11
Bloom	May 27	May 27 – Aug 26
Fall Sowing	September 6	Sep 6 – Sep 20

Growing Tips for Colorado

Direct-sow in early spring as soon as soil can be worked; seeds need a brief cold period for best germination (refrigerate for a few days before planting if spring arrives quickly). In zones 6+, fall-sow for the earliest spring bloom. Thin to 12 inches; do not over-fertilize — too much nitrogen produces foliage at the expense of flowers. Deadhead to prolong blooming or allow self-seeding for a naturalized colony.

Bachelor's Button in Other States

Frequently Asked Questions

When should I plant Bachelor's Button in Colorado?

Planting dates for Bachelor's Button in Colorado depend on your USDA zone. Colorado spans zones 4b, 5a, 5b, 6a, 6b, 7a. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Colorado for planting?

Colorado contains USDA hardiness zones 4b, 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.

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