Winter Fertilization of Lawns

Pink Snow Mold

People often choose tall fescue over bermuda lawns as they want a year-round green lawn.  There is no great advantage to having a tall fescue lawn in the winter that looks anemic at best due to neglect.  People want green.  Lawns will battle cold soil temperatures, saturated soils, extended damp and foggy periods, frost, and occasional diseases like rust and pink snow mold.  This is not exactly hitting tall fescue’s sweet spot of sunny, 65-75 degree days seen in the spring and fall. 

If no fall fertilization occurs then the likelihood of having a green lawn in January and February is dismal.  Tall fescue lawns need a bit of a push heading into the cold weather.  It needs to be pushing new growth albeit slow.  No grow…no green.

Can you just put any fertilizer out there in the fall and expect decent color?  You will probably see a response from most any fertilizer, but the level of response in colder weather will change with the source of nitrogen in the fertilizer.  I am a strong proponent of slow-release fertilizers as they are less likely to burn in the summer months and they feed the plants over an extended period of time allowing for greater efficiency and uniform growth.  When it comes to colder weather and cold soils we need to look at products that are either readily available for root uptake or can be converted by microbes to an available form in a reasonable time period.  You may have noted that many of the winter fertilizers have some form of nitrate nitrogen in the blend.  Nitrate is readily available to the plant and will be the form that with yield the fastest response.  Urea and ammonium forms may take 2-10 weeks to be converted to nitrates for plant uptake.  These are normally quick-release products in warm weather, but act like a slow-release in winter months.  I do not see a great benefit to sulfur-coated or poly-coated products at this time of year as they will likely not be available until sometime in February or March.

Healthy Tall Fescue 

How about other nutrients?  I always like to see some phosphorus, potassium, and even sulfur in the mix as well.  They may not add much to the plant color, but they can encourage healthier roots and tougher cells walls to fend off temperature stresses and diseases, and make more nutrients available by lowering the pH, respectively.

From past experience it is difficult to have a perfectly green lawn in the winter months.  Some yellow leaves and occasional pink snow mold or brown patch may show up even with a good fertilizer program.  Doing nothing will likely result in poor color for a few months. On the positive side, a good spring feeding and warmer weather will restore your lawn to a great green in no time.