When to plant zinnias
Plant zinnias 1–3 weeks after the last spring frost. Wait until the soil is at least 60°F. That works out to zone 5b (mid May to late May), zone 7a (late April to early May) and zone 9a (early March to late March).
Zinnias planting dates by zone
| Zone | Plant outdoors | zinnias ready from |
|---|---|---|
| 4a | May 22 – Jun 5 | Jul 28 |
| 4b | May 20 – Jun 3 | Jul 26 |
| 5a | May 18 – Jun 1 | Jul 24 |
| 5b | May 12 – May 26 | Jul 18 |
| 6a | May 7 – May 21 | Jul 13 |
| 6b | May 1 – May 15 | Jul 7 |
| 7a | Apr 22 – May 6 | Jun 28 |
| 7b | Apr 13 – Apr 27 | Jun 19 |
| 8a | Apr 3 – Apr 17 | Jun 9 |
| 8b | Mar 23 – Apr 6 | May 29 |
| 9a | Mar 9 – Mar 23 | May 15 |
| 9b | Feb 11 – Feb 25 | Apr 19 |
How to plant zinnias
| Plant as | seeds outdoors |
|---|---|
| Soil temperature | 60°F or warmer |
| Depth | 1/4 in |
| Spacing | 6–18 in |
| Light | Full sun |
| Time to bloom | 60–70 days |
Zinnias grow fast from direct sowing.
Good airflow prevents powdery mildew.
Sow every few weeks until midsummer.
Zinnias are native to Mexico and want heat: seeds sprout in 4–7 days in warm soil but rot in cold ground.
Water at the base rather than over the leaves to keep powdery mildew down; resistant series such as Zahara and Profusion help in humid areas.
For tall cutting varieties, cut stems just above a pair of leaves so new branches form.
When to expect flowers from zinnias
Cut often: zinnias are cut-and-come-again flowers.
Exact dates for your town: planting calendar · frost dates by state.
More flowers to plant
Begonias · Coleus · Marigolds · Sunflowers · Cosmos · Mums · Lantana · Hydrangeas