Hay storage ofCymbopogon martiniiandC. winterianus, either in the shade or in the open, was found to be advantageous during summer and rainy seasons, respectively. Maximum enhancements of 31.4% and 18.0% in oil content over the fresh distilled herbs were recorded in 5 and 7 days respectively. The safe limit of herb storage varied according to the species and storage conditions. Storage ofC. flexuosusherbage always caused a reduction in oil content except during the summer when it was not affected for three days under shade storage. Temperature and humidity were found to play a vital role in biosynthesis/accumulation of essential oils in stored herbs.