What temperature is too cold for harvesting tomatoes?
Written by
Tina Carter
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Temperature extremes. Below 50? F, cold symptoms such as cell membrane rupture and mealy texture develop. If above 90? F, tomatoes are sugary at harvest and decompose, degrading flavor and making the fruit mushy when cut. The best temperatures are between 55 and 70? F just after sun-up when most of the sugars are stored overnight.
Cold Damage Effects
- Cell membrane rupture below 50°F causes water leakage
- Pectin breakdown creates mealy texture within hours
- Flavor compounds degrade irreversibly
- Chilling injury shows as sunken patches
Heat Stress Consequences
- Enzyme deactivation above 90°F stops flavor development
- Accelerated respiration depletes sugars rapidly
- Skin softens increasing bruising susceptibility
- Uneven ripening occurs with white internal spots
Timing the harvest. When temperatures deviate from the norm, be particularly mindful of the timing of your harvest. A cold snap, for instance, dictates that you pick all breaker-stage tomatoes before the temperature drops lower than normal. A heat wave means harvesting them before 10 a.m., when the temperature is at its peak. In weather-crisis mode, the objective is to harvest fruit, not perfect tomatoes.
Temperature greatly impacts post-harvest handling. Produce harvested at less than 55°F should be warmed slowly to get ready for storage; produce harvested at greater than 85°F should be cooled directly to 70°F. Do not refrigerate tomatoes immediately after they are harvested, as this can exacerbate the damage caused by condensation.
Being aware of microclimates will help you avoid areas of extreme temperatures; south-facing home walls create areas with higher heat accumulation than the surrounding environment. Additionally, cold air tends to settle in low-lying areas during the night. During times of extreme heat waves, you can use shade cloth to protect your crops, while row covers should be used in colder weather.
Immediately take action on frost emergencies. All produce must be harvested at the maturation stage or higher. Individualize the wrapping of green tomatoes with paper to help facilitate longer storage time. Dispose of any frozen fruits with ice crystals, since raw fruit will become mushy once thawed.
Read the full article: When to Harvest Tomatoes for Best Flavor
