When to Plant Alliums in Minnesota
Ornamental alliums (Allium spp.) bridge the gap between spring and summer with their striking globe-shaped flower heads in shades of purple, violet, white, and pink. Blooming after tulips have faded, they extend the spring display well into early summer. 'Gladiator', 'Globemaster', and 'Purple Sensation' produce softball-sized heads on 18–36 inch stems, while smaller species create charming accents at border fronts. Deer and rodents shun them completely due to the characteristic onion scent. Dried seed heads provide architectural interest into fall.
Minnesota spans USDA hardiness zones 3b, 4a, 4b, 5a (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 Alliums planting dates based on your local frost dates.
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Alliums Planting Calendar for Minnesota
▸ Zone 3b ~135 day growing season · Full guide →
Last frost: May 10 · First frost: September 22 · 135 day season
| Activity | When | Date Range |
|---|---|---|
| Bloom | September 22 | Sep 22 – Oct 20 |
| Fall Sowing | August 11 | Aug 11 – Aug 25 |
▸ Zone 4a ~145 day growing season · Full guide →
Last frost: May 6 · First frost: September 28 · 145 day season
| Activity | When | Date Range |
|---|---|---|
| Bloom | September 28 | Sep 28 – Oct 19 |
| Fall Sowing | August 17 | Aug 17 – Aug 31 |
▸ Zone 4b ~155 day growing season · Full guide →
Last frost: May 1 · First frost: October 3 · 155 day season
| Activity | When | Date Range |
|---|---|---|
| Bloom | September 26 | Sep 26 – Oct 24 |
| Fall Sowing | August 22 | Aug 22 – Sep 5 |
▸ Zone 5a ~166 day growing season · Full guide →
Last frost: April 25 · First frost: October 8 · 166 day season
| Activity | When | Date Range |
|---|---|---|
| Bloom | October 1 | Oct 1 – Oct 29 |
| Fall Sowing | August 27 | Aug 27 – Sep 10 |
Growing Tips for Minnesota
Plant bulbs in fall, 3–4 times as deep as the bulb diameter (typically 4–6 inches for large types, 3 inches for small species). Space 6–8 inches apart for standard cultivars. Foliage often looks untidy as it dies back before bloom — plant around perennials that will conceal the yellowing leaves. Excellent drainage is essential; alliums rot in wet soils. Leave bulbs in place for naturalization; divide every 3–4 years when clusters become congested. Deadhead spent globes or leave for ornamental seedheads and self-sowing.
Alliums in Other States
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- 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 Alliums in Minnesota?
Planting dates for Alliums in Minnesota depend on your USDA zone. Minnesota spans zones 3b, 4a, 4b, 5a. Check the planting calendar above for your specific zone's frost dates and planting windows.
What zone is Minnesota for planting?
Minnesota contains USDA hardiness zones 3b, 4a, 4b, 5a. 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.