When to plant zinnias
tender annual
The short answer
Zinnias are planted out or sown outdoors after the last frost. Start them indoors 3 to 4 weeks before the last frost.
Zone 5: plant out or sow from Apr 30. Zone 7: plant out or sow from Apr 5. Zone 9: plant out or sow from Feb 20. See every zone or your state.
When to plant zinnias by USDA zone
Dates are worked out from each zone’s typical last frost, using the number of weeks the cited extension services give. Find your zone on the zone map. Zones 11 and above are frost-free, so timing there depends on heat and rain instead.
| Zone | Typical last frost | Start seed indoors | Plant out or sow |
|---|---|---|---|
| Zone 3 | May 15 | Apr 17 – Apr 24 | from May 15 |
| Zone 4 | May 10 | Apr 12 – Apr 19 | from May 10 |
| Zone 5 | Apr 30 | Apr 2 – Apr 9 | from Apr 30 |
| Zone 6 | Apr 15 | Mar 18 – Mar 25 | from Apr 15 |
| Zone 7 | Apr 5 | Mar 8 – Mar 15 | from Apr 5 |
| Zone 8 | Mar 20 | Feb 20 – Feb 27 | from Mar 20 |
| Zone 9 | Feb 20 | Jan 23 – Jan 30 | from Feb 20 |
| Zone 10 | Jan 30 | Jan 2 – Jan 9 | from Jan 30 |
Rule used: plant out or sow after the last frost; start seed indoors 3 to 4 weeks before the last frost.
When to plant zinnias in your state
Same rule, applied to each state’s typical last spring frost. States marked * span very different climates, so use your own frost date for the exact day - click a state for its frost dates.
| State | Typical last frost | Start seed indoors | Plant out or sow |
|---|---|---|---|
| Alabama | Mar 25 | Feb 25 – Mar 4 | from Mar 25 |
| Alaska * | May 17 | Apr 19 – Apr 26 | from May 17 |
| Arizona * | Mar 15 | Feb 15 – Feb 22 | from Mar 15 |
| Arkansas | Apr 3 | Mar 6 – Mar 13 | from Apr 3 |
| California * | Feb 20 | Jan 23 – Jan 30 | from Feb 20 |
| Colorado | May 5 | Apr 7 – Apr 14 | from May 5 |
| Connecticut | Apr 25 | Mar 28 – Apr 4 | from Apr 25 |
| Delaware | Apr 14 | Mar 17 – Mar 24 | from Apr 14 |
| District of Columbia | Apr 10 | Mar 13 – Mar 20 | from Apr 10 |
| Florida | Feb 12 | Jan 15 – Jan 22 | from Feb 12 |
| Georgia | Mar 25 | Feb 25 – Mar 4 | from Mar 25 |
| Idaho | May 10 | Apr 12 – Apr 19 | from May 10 |
| Illinois | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| Indiana | Apr 24 | Mar 27 – Apr 3 | from Apr 24 |
| Iowa | Apr 25 | Mar 28 – Apr 4 | from Apr 25 |
| Kansas | Apr 15 | Mar 18 – Mar 25 | from Apr 15 |
| Kentucky | Apr 18 | Mar 21 – Mar 28 | from Apr 18 |
| Louisiana | Mar 5 | Feb 5 – Feb 12 | from Mar 5 |
| Maine | May 14 | Apr 16 – Apr 23 | from May 14 |
| Maryland | Apr 14 | Mar 17 – Mar 24 | from Apr 14 |
| Massachusetts | Apr 24 | Mar 27 – Apr 3 | from Apr 24 |
| Michigan | May 10 | Apr 12 – Apr 19 | from May 10 |
| Minnesota | May 6 | Apr 8 – Apr 15 | from May 6 |
| Mississippi | Mar 20 | Feb 20 – Feb 27 | from Mar 20 |
| Missouri | Apr 15 | Mar 18 – Mar 25 | from Apr 15 |
| Montana | May 15 | Apr 17 – Apr 24 | from May 15 |
| Nebraska | Apr 30 | Apr 2 – Apr 9 | from Apr 30 |
| Nevada * | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| New Hampshire | May 13 | Apr 15 – Apr 22 | from May 13 |
| New Jersey | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| New Mexico * | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| New York * | May 1 | Apr 3 – Apr 10 | from May 1 |
| North Carolina | Apr 5 | Mar 8 – Mar 15 | from Apr 5 |
| North Dakota | May 15 | Apr 17 – Apr 24 | from May 15 |
| Ohio | Apr 25 | Mar 28 – Apr 4 | from Apr 25 |
| Oklahoma | Apr 1 | Mar 4 – Mar 11 | from Apr 1 |
| Oregon * | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| Pennsylvania | May 1 | Apr 3 – Apr 10 | from May 1 |
| Rhode Island | Apr 25 | Mar 28 – Apr 4 | from Apr 25 |
| South Carolina | Mar 25 | Feb 25 – Mar 4 | from Mar 25 |
| South Dakota | May 10 | Apr 12 – Apr 19 | from May 10 |
| Tennessee | Apr 10 | Mar 13 – Mar 20 | from Apr 10 |
| Texas * | Mar 15 | Feb 15 – Feb 22 | from Mar 15 |
| Utah | May 5 | Apr 7 – Apr 14 | from May 5 |
| Vermont | May 14 | Apr 16 – Apr 23 | from May 14 |
| Virginia | Apr 15 | Mar 18 – Mar 25 | from Apr 15 |
| Washington * | Apr 20 | Mar 23 – Mar 30 | from Apr 20 |
| West Virginia | May 5 | Apr 7 – Apr 14 | from May 5 |
| Wisconsin | May 10 | Apr 12 – Apr 19 | from May 10 |
| Wyoming | May 20 | Apr 22 – Apr 29 | from May 20 |
What extension services say
- Start zinnia seed indoors 4 weeks before the average frost-free date. Colorado State University Extension ↗
- Minnesota's calendar puts zinnia in mid-April, 3-4 weeks indoors. University of Minnesota Extension ↗
- Missouri's calendar also says mid-April and to direct seed into the final container. University of Missouri Extension ↗
- Annual flowers are usually planted in spring as soon as the danger of frost has passed. University of Missouri Extension ↗
- Zinnia is a tender annual that likes full sun; deadheading keeps it blooming. University of Illinois Extension ↗
- In Florida, zinnias can be planted in the spring throughout the state and also in the fall in South Florida; plant after the last frost date and give them space, because crowding encourages disease. UF/IFAS Gardening Solutions ↗
- Unlike many bedding plants, zinnias handle Florida's hot summers and bloom through the summer, often until the first frost. UF/IFAS Gardening Solutions ↗
Colorado's table also lists zinnia among flowers best direct-seeded two weeks before the average frost-free date. We show the later, frost-safe date because Missouri says annuals are planted once frost danger has passed and Illinois calls zinnia a tender annual.
Questions gardeners ask
When should you start zinnia seeds indoors?
About 4 weeks before the average last frost, according to Colorado State Extension. Minnesota's calendar gives 3-4 weeks.
When can you plant zinnias outside?
Once the danger of frost has passed. Illinois Extension lists zinnia as a tender annual, so it will not survive a frost.
Do zinnias need full sun?
Yes. Illinois Extension lists full sun and moist, well-drained soil.
Can you plant zinnias in the fall?
In South Florida, yes: UF/IFAS says zinnias can be planted in the fall there as well as in spring. For the rest of Florida it says spring.
Sources
- University of Illinois Extension: Zinnia
- Colorado State University Extension: Growing Annual Plants from Seed
- University of Minnesota Extension: Starting seeds indoors
- University of Missouri Extension: Starting Plants Indoors From Seeds (G6570)
- University of Missouri Extension: Herbaceous Ornamentals (MG9)
- UF/IFAS Gardening Solutions: Zinnia
Extension advice is local to the state that wrote it. Where the sources differ, both are shown. Dates in the tables are estimates from typical frost dates; your garden’s own last frost can differ by a week or more. How we source data.