You can start tomato seeds indoors in Connecticut around late March, then move sturdy seedlings outside in mid to late May once frost danger has passed and the soil is warm.

Best time to plant tomatoes in CT

  • Aim to transplant outdoors after your local last frost date, which is typically mid‑ to late May in much of Connecticut.
  • Tomatoes are warm‑season plants and can be damaged by temperatures below about 50°F, so waiting until both soil and air have warmed is important.

Indoor seed starting

  • Start tomato seeds indoors about 6–8 weeks before you expect to transplant.
  • With a mid‑ to late May transplant target, this usually means sowing seeds between early March and early April in Connecticut.
  • Some growers in CT use an approximate last frost date of around May 12 and then count backward: 8–10 weeks gives a window in early to mid‑March for sowing.

Transplanting outside

  • Transplant seedlings when they are about 6–8 inches tall and hardened off, and when daytime temperatures are consistently in the mid‑50s°F or above, with soil around 65°F.
  • Many CT garden centers and local guides recommend putting tomatoes, peppers, and eggplant in the ground in the latter half of May , when the risk of frost is low and the soil has warmed thoroughly.

Mini timeline example (typical CT garden)

  • Early–mid March: Start tomato seeds indoors under lights.
  • Late April–early May: Pot up seedlings if needed, begin hardening off on mild days.
  • Mid–late May: Transplant tomatoes into the garden after frost danger has passed and soil is warm.

If you’re near the cooler interior or higher‑elevation parts of CT, lean toward the later end of May; if you’re on the warmer coast, you can often plant a bit earlier in that mid‑ to late‑May window.

TL;DR: For “when to plant tomatoes in CT,” think: start seeds indoors in early–late March, and plant them outside in mid–late May once nights are mild and frost is done.

Information gathered from public forums or data available on the internet and portrayed here.