The critical temperature threshold for harvesting tomatoes and peppers

September temperature fluctuations create a high-risk environment for home gardeners. The gap between warm days and cold nights often triggers outbreaks of late blight, which can destroy crops in a matter of days. Specifically, when night temperatures drop below 45 °F (7 °C), heat-loving vegetables must be harvested immediately to prevent total crop loss. Harvesting Warm-Season Crops For tomatoes, peppers, and eggplants, the thermometer is the primary indicator for harvest timing. Once night temperatures hit the 41â–45 °F (5â–7 °C) range, the risk of phytophthora (late blight) peaks. In these conditions, gardeners should harvest fruits even if they are still green; they can ripen indoors at room temperature. Alexey Danilov, open-ground vegetable specialist: "At temperatures below 45 °F (7 °C), the cellular membranes of heat-loving crops are compromised, opening the door for fungal infections. Because fruit infection can occur lightning-fast, it is safer to move them to a dark area at 64â–72 °F (18â–22 °C) for final ripening."