COLUMBUS, OH—The late-season fertilization strategy is based on applying nitrogen (N) fertilizer in the late fall (mid November to early December period depending on temperature). Ideally, N should be applied just around the time that top growth has significantly stopped or ceased. N applied at this time should extend the greening of the turf longer into the late fall without additional top growth, so timing is critical. Not too early but not too late.

The extended greening results in the turf remaining photosynthetically active for as much as 4-6 weeks longer. The carbohydrate from this still active photosynthesis is translocated downward to support root growth and stolon/rhizome growth or the excess stored as a food reserve for next spring/summer. Spring green-up is usually enhanced resulting in earlier spring greening and additional photosynthesis and food production without the surge growth from a traditional early spring fertilization. REMEMBER – This usually eliminates the need for N fertilization early in the spring where appropriate late fall fertilization has occurred.

Using a less costly water-soluble source containing a fair portion of urea should help offset or lower the fertilization cost. In fact, the majority of late season fertilization research was done with urea and ammonium nitrate. One pound of N per 1,000 sq. ft. is considered an acceptable rate. Urea alone can be considered. A premium late-season fert on sandy soils could include the addition of IBDU in a Urea/IBDU combination of 35-50% IBDU to lessen potential N leaching losses over the winter. IBDU is relatively temperature independent in N release.
This item was posted originally by Dr. John R. Street on