The present invention provides a method of tandem cropping for increased production of up to 40% in wheat and mustard crops using varieties with phenological plasticity and temperature tolerance traits. The cereal bread wheat and oil seed mustard are traditional winter season (Rabi) crops in north India/Indo-Gangetic plains. This area experiences receding levels of warm weather and long days in September, October and November, progressive increase and then decrease of cold conditions and short days between November and March and onset of warm weather turning into summer and relatively longer days in March and April. Conventionally a seasonal crop of wheat or mustard or wheat followed by mustard or vice versa could be taken in the winter Rabi season of Indo-Gangetic plains to increase the production of these commodities. The concept has not occurred to persons skilled in the art of wheat cultivation and breeding and as far as is known there is no report of tandem cultivation of wheat under natural seasonal changes of agro-climates in areas where wheat cultivation is practiced. For tandem cropping, wheat and mustard cultivars must posses properties of flowering under long day or short day conditions, tolerating temperature gradients and reaching maturity earlier than normal.