When to plant dahlias
Plant dahlias 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).
Dahlias planting dates by zone
| Zone | Plant outdoors | dahlias ready from |
|---|---|---|
| 4a | May 22 – Jun 5 | Aug 27 |
| 4b | May 20 – Jun 3 | Aug 25 |
| 5a | May 18 – Jun 1 | Aug 23 |
| 5b | May 12 – May 26 | Aug 17 |
| 6a | May 7 – May 21 | Aug 12 |
| 6b | May 1 – May 15 | Aug 6 |
| 7a | Apr 22 – May 6 | Jul 28 |
| 7b | Apr 13 – Apr 27 | Jul 19 |
| 8a | Apr 3 – Apr 17 | Jul 9 |
| 8b | Mar 23 – Apr 6 | Jun 28 |
| 9a | Mar 9 – Mar 23 | Jun 14 |
| 9b | Feb 11 – Feb 25 | May 19 |
How to plant dahlias
| Plant as | tubers |
|---|---|
| Soil temperature | 60°F or warmer |
| Depth | 4–6 in |
| Spacing | 18–36 in |
| Light | Full sun |
| Time to bloom | 90–120 days |
| Start indoors | 4–6 weeks before the last frost (zone 6a: Mar 19 – Apr 2; zone 8a: Feb 13 – Feb 27) |
Do not water tubers until shoots appear; wet, cold soil rots them.
Pinch the center shoot when plants are a foot tall for more blooms.
In zones 7 and colder, lift tubers after frost blackens the leaves.
When to expect flowers from dahlias
Cut flowers when nearly fully open in the cool of the morning; they bloom until frost.
Exact dates for your town: planting calendar · frost dates by state.