When to Plant Zinnias
Sow zinnias outside 1 to 3 weeks after your last frost.
Zinnias at a glance
- Sow outside
- 1 to 3 weeks after your last frost
- Time to bloom
- 60 to 75 days from sowing
- In bloom for
- about 16 weeks
- Spacing
- 4 per square foot
- Frost
- Tender: frost kills it
Growing zinnias
Zinnias love heat and sun and grow quickly from seed sown outside in warm soil. Tall kinds make fine cut flowers; dwarf kinds suit the front of a bed. Butterflies visit them all summer. Pinch out the tip of each young plant once it has three pairs of leaves, and it branches into a bushier plant with more stems for cutting. Cut the flowers when the stem feels stiff just below the bloom, and they last a week or more in a vase.
Dates by hardiness zone
Typical dates for each zone; your ZIP code gives your own.
| Zone | Sow | In bloom |
|---|---|---|
| Zone 3a | Jun 4–18 | Aug 3 – Sep 14 |
| Zone 3b | May 24 – Jun 7 | Jul 23 – Sep 25 |
| Zone 4a | May 19 – Jun 2 | Jul 18 – Sep 28 |
| Zone 4b | May 15–29 | Jul 14 – Oct 1 |
| Zone 5a | May 10–24 | Jul 9 – Oct 5 |
| Zone 5b | May 8–22 | Jul 7 – Oct 10 |
| Zone 6a | May 6–20 | Jul 5 – Oct 16 |
| Zone 6b | Apr 30 – May 14 | Jun 29 – Oct 19 |
| Zone 7a | Apr 23 – May 7 | Jun 22 – Oct 12 |
| Zone 7b | Apr 12–26 | Jun 11 – Oct 1 |
| Zone 8a | Apr 5–19 | Jun 4 – Sep 24 |
| Zone 8b | Mar 24 – Apr 7 | May 23 – Sep 12 |
| Zone 9a | Mar 9–23 | May 8 – Aug 28 |
| Zone 9b | Feb 15 – Mar 1Nights are still cool before mid-February, so this starts a little later. | Apr 16 – Aug 6 |
| Zone 10a | Feb 15 – Mar 1 | Apr 16 – Aug 6 |
| Zones 10b–11b | Frost is rare here, so zinnias can go in from late winter, and again in late summer for a fall crop. | |
Good neighbors
Questions about zinnias
Can I start zinnias indoors?
You can, a few weeks before the last frost, but they grow so fast from seed sown outside that most gardeners sow them where they will bloom. Seedlings dislike having their roots disturbed.
How do I avoid mildew on zinnias?
Give the plants space and sun, and water at the base instead of over the leaves. Some varieties resist powdery mildew better than others.
