Vernalization is the response to cold temperatures before reproductive growth can occur in a flowering plant. It is the exposure to chilling conditions that will hasten growth of a seed or seedling. It is a process necessary for winter annuals as well as for monocarpic perennials which reside in temperate areas. It usually occurs between 0 and 18 degrees C depending on the type of plant. For example, winter wheat has an optimal temperature of between 0 and 7 degrees C. Low temperatures are required at germination and for a period of time until eventually growth will occur and the plant will produce flowers in the spring. It depends on the species of plant whether 0 degrees will be its optimal temperature for vernalization and whether this temperature will cause damage or not. In the case of winter wheat, it will not be harmful. Other plants have an optimal temperature of 5-10 degrees C. For those plants, 0 degrees may be harmful to the germinating seed.