Most tomato plants start to suffer below about 50–55 °F (10–13 °C), and anything near freezing (32 °F / 0 °C) can kill them, especially if it lasts more than a short time.

Quick Scoop

  • Ideal range: Tomatoes are warm‑season plants and grow best when daytime temps are roughly 70–85 °F (21–29 °C) and nights stay above about 55 °F (13 °C).
  • Growth slowdown: When nights drop into the mid‑40s to low‑50s °F (about 7–11 °C), plants usually survive but growth and flowering slow or stall, and leaves may look stressed or damaged.
  • Risk zone: Around 40 °F (4–5 °C), tissue damage becomes more likely, fruit quality can suffer, and repeated cold nights can weaken or kill plants.
  • Hard limit: Near freezing (32 °F / 0 °C) or a light frost, tomatoes are at real risk; a brief, very light frost might spare some foliage, but a harder or longer freeze usually kills the plant.
  • Cold‑tolerant types: Some specially bred, “cold‑set” or early varieties handle cooler nights a bit better and can set fruit at or just below 55 °F (13 °C), but they still are not true frost‑hardy.

Practical rule of thumb

  • Try to keep tomatoes above 55 °F (13 °C) for good growth and fruit set.
  • They will usually survive occasional dips to the mid‑40s °F (≈7 °C) , but expect slower growth and possible leaf damage.
  • Protect or move them if your forecast shows around 40 °F (4 °C) or lower , and treat any trip near freezing as an emergency for the plant.

Think of tomatoes as “summer guests”: they might endure a chilly evening in a jacket, but they absolutely do not want to spend the night in a frost.