Some plants are dependent on exposure to low temperature for flowering. This is called vernalisation. It allows plant to have adequate time to reach maturity. The ‘spring’ variety of wheat are sown in the spring and is harvested by the end of the same season while wWinter varieties if planted in spring would normally fail to flower or produce mature grain within a span of a the flowering season so they are sown in autumn. Then they take time to germinate and over winter they come out as seedlings. After that, they resume growth in the season of spring. Following which they are harvested around midsummer.

Winter wheat ^

^Spring wheat