Professors of Ohio and Colorado State Universities detail below the benefits of a fall fertilization program for lawns. They emphasize that the application of nitrogen fertilizers in late fall results in lawns that are visibly greener in color through summer of the following year, and without the excessive shoot growth of lawns fertilized in spring.

Late fall nitrogen fertilization

Late season nitrogen fertilization has been practiced by professionals for some time, but new evidence shows the wisdom of this technique.

Late season nitrogen fertilization, sometimes referred to as fall fertilization, has been utilized by turf managers for years. This type of fertility program involves the application of much of the season’s nitrogen during the late season months of September through December. It is important that late season fertilization not be confused with dormant and/or winter fertilization. The latter method implies that fertilizer applications are made after the turf has lost most or all of its green color and is not actively growing. This differs notably from the late season concept, which requires that nitrogen be applied before the turf loses its green color in the late fall.

Late season fertilization has become popular because many of the agronomic and aesthetic advantages attributed to its use supposedly are not realized when spring and/or summer fertilization are practiced. Purported advantages of the late season concept include: better fall and winter color; earlier spring green-up; increased shoot density; improved fall, winter, and spring root growth; and enhanced storage of energy reserves (carbohydrates) within the turf plant. Some claimed disadvantages include: increased chance of snow mold injury and decreased cold tolerance.

The effects of late-season nitrogen application on creeping bentgrass (Agrostis palustris Huds.) were documented by Powell et al. 2 3 and Snyder and Schmidt 4 in research conducted in Virginia during the late 60s and early 70s. In those studies, it was clearly shown that the quality and root production of creeping bentgrass grown in the transition zone could be enhanced by using late-season nitrogen applications and avoiding early spring nitrogen fertilization.

While researchers 1 and turfgrass practioners alike have demonstrated that the year-around quality of Kentucky bluegrass can also be enhanced by late season nitrogen fertilization, research efforts concerning effects on root growth and plant carbohydrate status have been lacking. This article will review past studies which have examined late-season nitrogen fertilization and relate those findings to the results of work recently completed at Ohio State University that assessed how the timing of nitrogen application can influence the quality, carbohydrate status, and root growth of Kentucky bluegrass.