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When to Plant Petunia in Alaska

Petunias (Petunia x hybrida) are warm-season tender annuals prized for their prolific, trumpet-shaped blooms in nearly every color. They perform from hanging baskets to garden borders and bloom continuously from late spring until frost, provided spent flowers are removed regularly.

Alaska spans USDA hardiness zones 2a, 2b, 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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Find Your County

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

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

Petunia Planting Calendar for Alaska

Zone 2a ~94 day growing season · Full guide →

Last frost: May 30 · First frost: September 1 · 94 day season

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors June 13 Jun 13 – Jun 27
Bloom September 5 Sep 5 – Oct 3
Zone 2b ~111 day growing season · Full guide →

Last frost: May 22 · First frost: September 10 · 111 day season

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors June 5 Jun 5 – Jun 19
Bloom August 28 Aug 28 – Oct 2
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 March 8 Mar 8 – Mar 22
Transplant Outdoors May 24 May 24 – Jun 7
Bloom August 9 Aug 9 – 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 March 4 Mar 4 – Mar 18
Transplant Outdoors May 20 May 20 – Jun 3
Bloom August 5 Aug 5 – 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 February 27 Feb 27 – Mar 13
Transplant Outdoors May 8 May 8 – May 22
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 February 28 Feb 28 – Mar 14
Transplant Outdoors May 2 May 2 – May 16
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 February 21 Feb 21 – Mar 7
Transplant Outdoors April 25 Apr 25 – May 9
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 February 6 Feb 6 – Feb 20
Transplant Outdoors April 10 Apr 10 – Apr 24
Bloom June 19 Jun 19 – Oct 2
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 28 Jan 28 – Feb 11
Transplant Outdoors April 1 Apr 1 – Apr 15
Bloom June 10 Jun 10 – Sep 30
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 21 Jan 21 – Feb 4
Transplant Outdoors March 18 Mar 18 – Apr 1
Bloom May 27 May 27 – Sep 23
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 January 11 Jan 11 – Jan 25
Transplant Outdoors March 8 Mar 8 – Mar 22
Bloom May 17 May 17 – Sep 20

Growing Tips for Alaska

Start seeds indoors 8–10 weeks before last frost; seeds need light to germinate — press onto moist mix surface, do not cover. Transplant after last frost once nights stay above 50°F. Pinch back leggy plants mid-summer to encourage bushy re-bloom. Wave/spreading types tolerate light shade but bloom less. Feed every 2 weeks with balanced fertilizer once established.

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Frequently Asked Questions

When should I plant Petunia in Alaska?

Planting dates for Petunia in Alaska depend on your USDA zone. Alaska spans zones 2a, 2b, 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 2a, 2b, 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.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals, University Cooperative Extension planting guides. Last updated: June 2026.