Within each maturity group, varieties may differ in maturity by up to fifteen days. In general, a change in latitude of approximately 100 miles will necessitate a change in maturity groups. After June 21, daylength begins to shorten. In general, for each two to three day delay in planting date, maturity is delayed by only one day. So, for example, a variety planted on May 20 that matures in 130 days on September 27, might only require 110 days to maturity if planted on June 20.
Temperature also affects the rate at which soybeans develop and mature.
Warm temperatures accelerate flowering and maturity, whereas cool temperatures delay flowering and maturity. Therefore, a delay in planting shortens the life cycle of a soybean variety, since it is exposed to both warmer temperatures and shorter daylengths. Since soybeans respond in this manner, it is much more difficult to classify them on the basis of maturity days or growing degree days as is the case in corn. Unlike corn, adapted soybean varieties can be planted later without switching to an earlier maturity group.