When to plant Dahlia in Zone 4a
In Zone 4a, Dahlia: start seeds indoors around Apr 17–May 1; transplant outdoors around May 22–May 29. Expect to harvest around Aug 30–Sep 6.
| Step | When |
|---|---|
| Start seeds indoors | Apr 17 – May 1 |
| Transplant outdoors | May 22 – May 29 |
| Harvest | Aug 30 – Sep 6 |
Tip: Plant tubers after frost. In cold zones, lift and store them indoors over winter.
Zone 4a averages a last spring frost around May 15 and a first fall frost around Sep 18. These are zone averages — look up your ZIP for your exact area.
See the full Zone 4a calendar in the tool →