Soybean maturity group tells you where a variety is adapted to use the season—not a guaranteed number of days to harvest. Find the planning band around your farm, then narrow it with planting date, frost risk, field goals, and local trial results.
Group 2, later than a 2.1 and earlier than a 2.8. It is a relative position inside the group; weather can change the actual calendar date.
Choose a state or click the map. The band is a starting point for full-season grain soybean—not a seed prescription.
Soybean is photoperiod-sensitive. The variety’s genetics respond to the length of darkness, which is why best-fit groups generally move from very early numbers in the north to later numbers in the south.
A variety that is too early can flower with too little plant growth and leave yield potential unused. A variety that is too late may not finish seed fill before frost or your harvest deadline.
The decimal ranks varieties within a major group. One whole group is often roughly a ten-day maturity difference, but temperature, planting date, and genetics keep that from being a fixed countdown.
R7 begins when one normal pod reaches mature color; R8 means 95% of pods have mature color. Harvest still follows dry-down, so “maturity” and “combine-ready” are not the same date.
Start inside the state band. Remove varieties clearly outside the locally adapted season.
Use university trial locations like your farm. Compare multiple sites and years, not one winning plot.
Build a harvest spread. A few well-adapted maturities can distribute weather and harvest risk.
Fourteen years of variety-performance data from 27 states. This is the primary geographic framework for the layer.
Northern-zone updateUses public Northern Uniform Soybean Tests with photoperiod, temperature, and elevation to update northern optimum maturity zones.
Farmer interpretationExplains maturity group versus relative maturity and shows why a state can successfully use varieties outside its single optimum zone.
Selection workflowConnects photoperiod, the common ±0.5 planning window, and multi-location performance trials.
Method note. Colors show the center of a state’s adaptation band, not a hard border. Ranges summarize the national zones and current land-grant guidance where available. States with sparse commercial evidence are deliberately uncolored. This educational layer does not replace current county-level Extension or seed-company placement advice.