Crops are harvested according to calendar.
The Hindu Calendar usually has 12 months. However, it may also have 13 months, as each month begins with the new moon. Each lunar month is given the name of the solar month in which it begins.
When two new moons occur in the same solar month, the two lunar months will both be known by the same name, but will have adhika placed before the name of the first month.Occasionally a solar month may occur with no new moon.
In event of this happening, the solar month is known as a ksaya month. The twelve months of the lunar year correspond to the following calendar months.