Persistent wet weather is likely to push soybean planting into late May-early June in many areas. Late planting reduces the cultural practice options for row spacing, seeding rate, and relative maturity.

Row spacing. The row spacing for June planting should be 7.5 to 15-inches, if possible. Row width should be narrow enough for the soybean canopy to completely cover the interrow space by the time the soybeans begin to flower. The later in the growing season soybeans are planted, the greater the yield increase due to narrow rows.

Seeding rate. Higher seeding rates are recommended for June plantings. Final (harvest) population for soybeans planted in June should be 130,000 to 150,000 plants/acre. (For May planting dates, a final stand of 100,000 to 120,000 plants/acre is generally adequate.)

Relative maturity. For June planting dates, plant the latest maturing variety that will reach physiological maturity before the first killing frost. This is to allow the plants to grow vegetatively as long as possible to produce nodes where pods can form before vegetative growth is slowed due to flowering and pod formation. The recommended relative maturity ranges are shown in the table below.

  Planting Date Suitable Relative Maturity
Northern Ohio June 1-15 3.2-3.8
  June 15-30 3.1-3.5
  July 1-10 3.0-3.3
Central Ohio June 1-15 3.4-4.0
  June 15-30 3.3-3.7
  July 1-10 3.2-3.5
Southern Ohio June 1-15 3.6-4.2
  June 15-30 3.5-3.9
  July 1-10 3.4-3.7