You Can Dig It

Don't feed the lawn

By Jim Janke | Mar 31, 2017
You might be tempted to fertilize your lawn, but resist the urge. There's a decent chance you're doing more harm than good.

This is the time of year that lawn care ads overwhelm your mailbox and TV screen. Pallets of fertilizer are prominently displayed at the home center with exhortations to feed your lawn now.

But the local experts say that fertilizing your lawn in spring or summer can do more harm than good. Who’s right?

The fertilizer and lawn care companies typically advertise a four-part program:

— Late winter/early spring: Fertilizer plus crabgrass preventer

— Mid-spring: Fertilizer plus weed killer

— Summer: Fertilizer plus insecticide

— Fall: Fertilizer for winterizing

Grasses like Kentucky blue, perennial rye and fescues grow well in the mountains. These cool-season grasses are at their best from September through April, and slow down in summer as part of their natural growth cycle.

Fertilizing in spring or summer forces these grasses to grow abnormally fast, which stresses the lawn; reduces its disease and insect resistance; requires additional watering to keep growth spurts from dying; and wears out lawn mower blades.

With the exception of the fall application, these programs don’t give cool-season grasses what they need when they need it.

If in spring or summer, you need to prevent crabgrass, kill broadleaf weeds, or treat for insects. Buy only that chemical component without the fertilizer and apply according to the instructions on the label.

Your lawn will thank you.

When you fertilize, don’t overdo it. Runoff from excessive fertilizing has been linked to major pollution problems in some of the nation’s waterways.

Add 1/2 to 1 pound of nitrogen each time per 1,000 square feet (for example, an area of 25 by 40 feet.) A typical lawn fertilizer might have an analysis of 30-0-4; the first number listed is the nitrogen content.

Spread 3.5 pounds of a 30-0-4 fertilizer to add 1 pound of nitrogen to 1,000 square feet. If you want to add 1/2 pound of nitrogen to this area, use half as much.

The soils in Western North Carolina are typically acidic; test each area of your lawn every few years to check the pH (6.0 to 6.5 is ideal.) The soil test will tell you how much lime to add if your pH is low.

In addition, our red clay is often deficient in phosphorus, and most lawn fertilizers do not contain this important mineral (the middle number on the bag.) So the test results might recommend using a complete fertilizer like 10-10-10 or 5-10-5 to get the phosphorus higher.

If you have trouble interpreting the soil test results, call the Extension and they’ll bring up your tests online and tell you what you need to do. Soil tests are free between April and October; kits are available at the Extension Center on Raccoon Road.

For established lawns, fertilizing once each year in the fall might be all you need. Each October, I use one 15,000 square foot bag of slow release fertilizer on my 17,000 square foot lawn, and add lime if recommended by the soil tests.

“Carolina Lawns” is an excellent publication available from the North Carolina Cooperative Extension Service that discusses which grasses to plant; how to establish a new lawn; mowing and watering; weed and pest control; core aeration and power raking; and more.

Download a copy at http://www.turffiles.ncsu.edu/Files/Documents/Publications/2008/Carolina_Lawns.pdf.

Jim Janke is an Extension Master Gardener volunteer in Haywood County. For more information, call the Haywood County Extension Center at 456-3575. © 2017 NC State University.

Comments (1)
Posted by: David Eachus | Apr 03, 2017 06:54

Jim, Thanks for the timely and valuable update.  I'll definitely get my soil tested in April.



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