Fall is here and I’m ready to fertilize the lawn. I forgot last year and noticed there were many more weeds such as clover and black medic infesting the lawn.
I have purchased a generic 16-16-16 fertilizer. The numbers refer to amount of nitrogen, phosphorus and potassium in the product. I use this lower nitrogen rate in the fall, instead of my spring 21-0-0 fertilizer, to allow growth to slow down a bit. However, the addition of phosphorus and potassium gives the lawn the nutrients necessary to boost root development and food storage in the grass plants in time for winter. This will make for strong growth in the spring. Thriving grass in the spring should outcompete the black medic, a clover-like annual plant with runners and yellow flowers, and other weeds. By following up in the spring with a high nitrogen fertilizer, I should be able to slow down the weeds without using an herbicide. I choose not to use herbicide/fertilizer combinations because of the damage the herbicide can do to trees and shrubs and also because there is an insufficient amount of fertilizer in these products for good lawn nutrition.
A day or so before I fertilize, I water the lawn thoroughly. Then, I will use a fertilizer spreader with wheels for even coverage because I have so much area. It’s too difficult to apply fertilizer evenly with a hand-held spreader. I dump a 20-pound bag of fertilizer in the hopper with the controller set at half the amount recommended on the bag. Then, I go one direction first, say north/south, and follow up by going east/west. By using this cross-hatch pattern, I apply the full amount and avoid streaks where I missed fertilizing some areas and applied too much in others. Too much fertilizer burns the lawn and turns it brown, so I make a point of turning the spreader off when I turn to make another pass.
After I fertilize, I water again to wash the fertilizer off the surface off the grass blades and into the soil. Fertilizer left on the surface of the blades can burn the grass. Sometimes people ask me if they should mow before fertilizing. If the grass is excessively long, that might be a good idea, to allow the fertilizer pellets to get to the soil instead of sitting on long grass blades.
A strong healthy lawn next spring will be the best defense against lawn weeds. The lawn will also be better able to resist drought stress.
JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Reach her at firstname.lastname@example.org