When to Plant Zinnia in Alaska

Zinnia (Zinnia elegans) is a fast-growing, heat-loving annual that produces bold, dahlia-like blooms from early summer until hard frost. One of the easiest flowers to grow from direct-sown seed, zinnias thrive in hot, dry conditions and are magnets for butterflies and beneficial insects. They make excellent companion plants alongside marigolds in the vegetable garden.

Alaska spans USDA hardiness zones 3b, 4a, 4b, 5a, 5b, 6b, 7a, 7b, 8a (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 Zinnia planting dates based on your local frost dates.

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Zinnia Planting Calendar for Alaska

▸ Zone 3b ~135 day growing season · Full guide →

Last frost: May 10 · First frost: September 22 · 135 day season

Activity	When	Date Range
Start Indoors	April 12	Apr 12 – Apr 26
Transplant Outdoors	May 24	May 24 – Jun 7
Direct Sow	May 24	May 24 – Jun 14
Bloom	August 2	Aug 2 – Oct 4

▸ Zone 4a ~145 day growing season · Full guide →

Last frost: May 6 · First frost: September 28 · 145 day season

Activity	When	Date Range
Start Indoors	April 8	Apr 8 – Apr 22
Transplant Outdoors	May 20	May 20 – Jun 3
Direct Sow	May 20	May 20 – Jun 10
Bloom	July 29	Jul 29 – Oct 7

▸ 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	April 3	Apr 3 – Apr 17
Transplant Outdoors	May 8	May 8 – May 22
Direct Sow	May 8	May 8 – May 29
Bloom	July 17	Jul 17 – Oct 2

▸ 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 28	Mar 28 – Apr 11
Transplant Outdoors	May 2	May 2 – May 16
Direct Sow	May 2	May 2 – May 23
Bloom	July 11	Jul 11 – Oct 3

▸ 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 21	Mar 21 – Apr 4
Transplant Outdoors	April 25	Apr 25 – May 9
Direct Sow	April 25	Apr 25 – May 16
Bloom	July 4	Jul 4 – Oct 3

▸ 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	March 6	Mar 6 – Mar 20
Transplant Outdoors	April 3	Apr 3 – Apr 17
Direct Sow	April 3	Apr 3 – Apr 24
Bloom	June 12	Jun 12 – Sep 18

▸ 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 25	Feb 25 – Mar 11
Transplant Outdoors	March 25	Mar 25 – Apr 8
Direct Sow	March 25	Mar 25 – Apr 15
Bloom	June 3	Jun 3 – Sep 23

▸ 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	February 18	Feb 18 – Mar 4
Transplant Outdoors	March 18	Mar 18 – Apr 1
Direct Sow	March 18	Mar 18 – Apr 8
Bloom	May 27	May 27 – Sep 30

▸ Zone 8a ~255 day growing season · Full guide →

Last frost: March 8 · First frost: November 18 · 255 day season

Activity	When	Date Range
Start Indoors	February 8	Feb 8 – Feb 22
Transplant Outdoors	March 1	Mar 1 – Mar 15
Direct Sow	March 1	Mar 1 – Mar 22
Bloom	May 10	May 10 – Sep 27

Growing Tips for Alaska

Direct-sow after last frost when soil reaches 60°F; seeds germinate in 5-7 days. In zones 3-5 a brief indoor start (4 weeks) is worthwhile but transplant carefully — zinnias dislike root disturbance. Deadhead frequently to extend bloom. Excellent cut flower; harvesting regularly encourages branching. Avoid overhead watering to reduce powdery mildew.

Zinnia in Other States

Frequently Asked Questions

When should I plant Zinnia in Alaska?

Planting dates for Zinnia in Alaska depend on your USDA zone. Alaska spans zones 3b, 4a, 4b, 5a, 5b, 6b, 7a, 7b, 8a. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Alaska for planting?

Alaska contains USDA hardiness zones 3b, 4a, 4b, 5a, 5b, 6b, 7a, 7b, 8a. 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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