Most rye varieties are sown in the autumn and harvested the next summer, i.e. so called winter rye. There is also Midsummer rye (also called Swidden rye) and spring rye. Older rye varieties often grow very tall - up to two meters. The long straw was used for e.g. thatched roofs. Rye is very good at competing with weeds. Rye grows better on poorer soils than wheat does, and also withstands colder winters than wheat does. Rye used to be the most important and most grown cereal in Sweden, but the area grown has decreased significantly over the last 100 years. Rye is wind pollinated and if you want to grow several different varieties for seed they must therefore be separated by hundreds of meters.