When to plant Dahlia in Zone 4b
In Zone 4b, Dahlia: start seeds indoors around Apr 12–Apr 26; transplant outdoors around May 17–May 24. Expect to harvest around Aug 25–Sep 1.
| Step | When |
|---|---|
| Start seeds indoors | Apr 12 – Apr 26 |
| Transplant outdoors | May 17 – May 24 |
| Harvest | Aug 25 – Sep 1 |
Tip: Plant tubers after frost. In cold zones, lift and store them indoors over winter.
Zone 4b averages a last spring frost around May 10 and a first fall frost around Sep 22. These are zone averages — look up your ZIP for your exact area.
See the full Zone 4b calendar in the tool →