Fall fertilization, good or bad for my lawn? (10-03-2005)

The application of winterizing fertilizer to Southern lawns continues to be a controversial management practice. There are some who profess that applying fertilizer, particularly nitrogen late in the year, will enhance winter diseases and winterkill. Research at Mississippi State and other universities in the South, however, have shown that late season fertilization to Bermudagrass improved fall color through October and gave significantly higher spring color ratings with no indication of increasing winterkill potential.

The research data also indicate that the winterkill phenomenon is probably due to a combination of factors, such as previous cultural and chemical management practices, environment, pathogens, etc., and cannot be solely attributed to late season fertilization. Late fall applications of potassium is standard practice as research documents that potassium promotes winter hardiness and disease resistance in turf.

The argument of increased potential for disease and promotion of winter weed growth may be valid, but those turf managers who maintain high fertility programs are also most likely to maintain good disease and weed control programs as well.

While the Extension publication “Establish and Manage Your Home Lawn” provides general guidelines for fertilization and timings of applications, it does not exclude additional “winterizing fertilization” for those who want to maintain a higher level of turf management. Winterizing fertilizers are generally formulated to contain lower ratios of nitrogen to potassium with the nitrogen sources being of slow release in plant availability. Just remember that any fertilization should be based on soil test analysis and turf use requirements.

Published October 3, 2005

Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. wwells@ext.msstate.edu