SummaryNicotiana benthamianais increasingly used for transient gene expression to produce antibodies, vaccines, and other pharmaceutical proteins but transient gene expression is low in fully developed, 6–8‐week old plants. This low gene expression is thought to be caused by the perception of the cold shock protein (CSP) ofAgrobacterium tumefaciens. The CSP receptor is contested because bothNbCSPR andNbCORE have been claimed to perceive CSP. Here, we demonstrate that CSP perception is abolished in 6‐week‐old plants silenced forNbCORE but notNbCSPR. Importantly, olderNbCORE‐silenced plants support a highly increased level of GFP fluorescence and protein upon agroinfiltration. The drastic increase in transient protein production inNbCORE‐depleted plants offers new opportunities for molecular farming, where older plants with larger biomass can now be used for efficient protein expression.