Will Tomatoes Die at 35 Degrees?

Damage

• A light frost and freezing temperatures of 32 degrees Fahrenheit can kill tomato plants. Close-to-freezing temperature of 35 degrees Fahrenheit can also do significant damage, especially during prolonged exposure. According to the Ontario Ministry of Agriculture and Food, 35 degrees Fahrenheit falls within the range that makes the plants susceptible to chilling injury. This can include wilting of the plants, stunted growth, damaged fruit, dead foliage, impaired root development and an increased risk of diseases.

Temperatures

• Consider transplanting tomato seedlings when the soil has warmed above 60 degrees Fahrenheit. Ideally, nighttime temperatures are consistently above 50 degrees and daytime temperatures are at least 65 degrees. Avoid transplanting too early, because temperatures below 50 degrees and a late frost can stress the plants. To transplant about three weeks early, spread black plastic over the soil to hasten the soil-warming process. Then seed or transplant in holes made in the plastic.

Protection

• If there's a threat of a cold spell, protect your tomatoes with tarps, hot caps, blankets, plastic tunnels or floating row covers until the threat passed. These protective methods are draped over the plants and insulate them. If you've used these protective methods early on in the growing season, remove them as soon as the temperature reaches 85 degrees Fahrenheit. If row covers aren't an option, harvest green tomatoes and ripen them indoors by individually wrapping them in newspaper and exposing them to temperatures of 60 to 65 degrees Fahrenheit.

Hardening Off

• Gradually acclimating, or hardening off, your seedlings before transplanting them is essential to your success. Over a one-week period, gradually reduce your watering frequency and stop fertilizing the seedlings. Place them outside in a sheltered area for two hours a day and gradually lengthen their exposure to the elements. At the end of the week, the slow-growing plants are more tolerant of the new environment and are ready to transplant.