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High Nighttime Temperatures Can Affect Fruiting

Making It Grow! Minute logo

Hello Gardeners, I’m Amanda McNulty with Clemson Extension and Making It Grow. Lots of calls are coming to   Extension offices about vegetable plants that have lush and plentiful foliage but are not setting fruits, especially beans and tomatoes. There are several factors at play. One is high night time temperatures. Tony Melton explains that plants cool themselves by a process called transpiration – basically sweating. Special structures called stomata, located on the underside of leaves, function like windows – opening in the daytime so that plants can take in ambient air with the carbon dioxide necessary for photosynthesis. They also can open these structures to release water vapor which evaporates and cools the plants. When night temperatures are high, plants can’t rest but must continue to transpire, using stored carbohydrates for energy to continually move water from the roots to the leaves, carbohydrates that would otherwise   be used to make fruits and vegetables.  

Amanda McNulty is a Clemson University Extension Horticulture agent and the host of South Carolina ETV’s Making It Grow! gardening program. She studied horticulture at Clemson University as a non-traditional student. “I’m so fortunate that my early attempts at getting a degree got side tracked as I’m a lot better at getting dirty in the garden than practicing diplomacy!” McNulty also studied at South Carolina State University and earned a graduate degree in teaching there.