AbstractWhen growing in the field, Brassica juncea cv. RH-30 was exposed to freezing temperature in 2 years at 7 different ontogenetic stages of development, i.e. vegetative (20 days after sowing—DAS), bud initiation (30 DAS), flowering initiation (40 DAS), 27, 50, 90 and 100% siliqua development stages (55, 75, 90 and 125 DAS respectively).Varying levels of determinal impact of freezing were observed at different stages. The crop was most sensitive to freezing temperature at early or middle pod development stages (55 & 75 DAS) whereas it hardened as the maturity period progressed. Plants did exhibit a high tolerance to freezing at vegetative and bud initiation stages (20 & 30 DAS respectively) while moderate tolerance was observed at flowering initiation stage (40 DAS).The crop may avoid natural frost by introducing management practices that ensure that the crop does not pass through the early siliqua development stage during the most common period of frost occurrence.