Does my lawn need a fall feeding?

ASK THE HORT AGENT

Question Does my lawn need a fall feeding?

Answer The concept of “feeding” your lawn is misleading. Grass does not have a mouth. Therefore, it does not eat. You feed pets, alligators, bears or big government, but not turf. Plants absorb nutrients through their roots like a sponge absorbs water.

However, it would be appropriate to think of fertilizer as calories. Imagine your lawn is a professional boxer. It has to be in shape. An overweight or a skinny boxer probably won’t make it 15 rounds. Too much fertilizer, like too much sugar, can be a bad thing.

Fall fertilization depends on the type of grass in your yard. Cool season grasses, like fescue and rye grass, begin to grow in September. As they grow, a demand for fertilizer is created. The addition of one pound of nitrogen per 1,000 square feet is the standard recommendation for cool season grasses in September.

Fall fertilization has a different meaning for warm season grasses like centipede, zoysia or St. Augustine. These grasses are shutting down, not cranking up. They do NOT need nitrogen in September. Tender new growth in September will result in frost damage in October or November. However, there is a nutrient that will benefit warm season grasses without promoting leaf growth. It is potash (or potassium).

Potassium (or K on the periodic chart) is involved in cellular metabolism, environmental stress resistance (hot and cold extremes), disease incidence, internal water management (drought resistance) and wear tolerance.

Northerners (aka Yankees) often refer to high potash fertilizers as winterizers. While potash plays a role in cold tolerance, it is obviously important throughout the year. Fertilizer potassium is mined from the ground as the salt potassium chloride (KCl), also called muriate of potash or simply potash. On a bag of fertilizer, potash is the third number (0-0-X).

In September, fertilize Bermuda, zoysia and centipede with 1 pound of potash (K2O) per 1,000 square feet. There are three products on the market which can supply potash without supplying nitrogen. The correct rates per 1,000 sq ft are 1.6 pounds of muriate of potash (0-0-60), 2 pounds of potassium sulfate (0-0-50), or 5 pounds of sul-po-mag (0-0-22).

During the growing season, normal fertilization practices focus on nitrogen. However, potash is a component of these fertilizers. For these applications, the rate of potassium can be raised or lowered relative to the nitrogen (ex. 10-10-10 or 10-10 20). Soil tests are the best tool for determining potassium rates at these times. Incorrect fertilization timing and rates can cause problems for any grass. Excessive fertilization can also have negative impacts on our natural environment.

For more fertilizer info, visit http://www.turf.uiuc.edu/extension/ext-fert.html If you don’t have internet access, then call the Extension Office at 893-7533 or email me at gpierce@harnett.org

Your grass gets hit hard by drought, heat, cold and other forces of nature. As you fertilize your lawn, simply tell your grass “Keep your head down. You can do it Rocky.”

Gary L. Pierce

Horticulture Extension Agent

Harnett County