You should plant tomatoes outside after the last spring frost has passed and when both air and soil have warmed up enough, typically in late spring to early summer , depending on your climate zone.

Quick guideline for timing

  • Seeds indoors: Start tomato seeds about 6–8 weeks before your area’s last frost date.
  • Transplant outdoors: Move seedlings outside when:
    • Night temps stay above 50°F (10°C).
* **Soil is reliably warm** (around or above 60°F / 15°C).

* All risk of **late frost is gone** for your region.

Rough timing by region (in the US)

Region / climate| When to plant tomatoes
---|---
Southern US (warm)| Often late winter to early spring; even January–February for some areas. 13
Mid‑Atlantic / similar| Late March to early May , after last frost. 1
Pacific Northwest| Late spring (April–May). 1
Northeast / Midwest| Late May to early June when nights are warm enough. 15

Best time of day to plant

  • Plant tomatoes in the late afternoon or early evening , when the sun is less intense, to reduce transplant shock and let plants adjust overnight.

If you’re in a cooler zone

  • Choose short‑season or early‑maturing varieties and still wait until the minimum temp conditions are met ; tomatoes planted too early in cold soil will just “sit there” instead of growing.

If you tell me your city or USDA hardiness zone, I can give you a more precise “when to plant tomatoes” window for your exact location.