Should I Fertilize the Lawn with Nitrogen?

At the first sign of green grass in the spring, it is tempting to dust off the fertilizer spreader to apply nitrogen to the lawn. If you applied nitrogen late last fall or winter, there’s no need to apply nitrogen this spring because the lawn already should be starting to green up.

Grass 2015 May_Jun

Applying nitrogen now also will make grass less heat and drought tolerant and cause more problems with weeds and diseases. Weeds compete with grass for moisture and nutrients.

But, if you did not fertilize the lawn last fall, applying nitrogen this spring will be beneficial because it will green the lawn and make it look better for a few weeks.

However, spring fertilization causes such fast top growth you have to mow every four to five days in April and May to remove only one-third to one-half of the grass leaves each time. Cutting several inches of top growth at one time creates excess clippings that smother the grass below, or must be bagged and added to landfill debris.

Frequent mowing may serve as a reminder that a fall nitrogen application is much better for your lawn and you.

Although early spring usually is not the best time to apply nitrogen, it is the right time to apply a pre-emergence herbicide for persistent crabgrass problems. Since a pre-emergence herbicide is only effective before crabgrass germinates, be sure to apply it prior to mid-April and before crabgrass germinates and begins to compete with your grass.

Apply a post-emergence herbicide to control broadleaf weeds such as dandelion, chickweed, henbit, wild strawberry and ground ivy. Broadleaf weeds must be actively growing for the herbicide to work. Don’t spray when the wind is blowing or the temperature is 85 to 90 degrees Fahrenheit because you could damage other plants in the yard or garden. If it’s too hot for a general application, spot treat broadleaf weeds with a ready-mix foam or aerosol product.

Submitted by Professor Emeritus A.J. Powell, University of Kentucky, Department of Plant and Soil Sciences