Lawn Fertilizing

Karen Cambre, Sharpe, Kenneth W.

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News Article for April 2, 2018

We have had some warm nights and that makes lawn grasses grow. Once the grasses have been green for 2 to 3 weeks, you can fertilize them and get maximum benefit. When questioned for a calendar date, I use April 15th as a guide to fertilize lawns, but a better method is to wait until you have cut the grass twice. (Cutting early winter weeds and chopping leaves does not count as one.)

I like to use soil sample results to guide my fertilizer recommendations, especially where you are having problems. Another component to consider is how much do you really like to cut grass? We can safely use 0.5 to 1.0 pound of actual nitrogen per 1000ft². I like to use the lower rates for carpet and centipede and the higher rates for St. Augustine and Bermuda grass.

To accomplish the 0.5 pound of nitrogen rate for centipede and carpet grass you can apply 6 pounds of 8-8-8 fertilizer or 4 pounds of 13-13-13 per 1000ft². For St. Augustine and Bermuda grasses (1.0 # nitrogen) you can use 12 pounds of 8-8-8 or 8 pounds of 13-13-13/1000ft².

First, measure your lawn and multiple length time width to get the total square feet. If you do not have a scale to weigh out your fertilizer, a quart of granular fertilizer weighs about 2 pounds. The way to remember is “a pint is a pound the whole world round”, but this only works for granular fertilizers.

Use a broadcast applicator to give you even coverage. Also, be sure to apply the fertilizer to a dry lawn. If the grass blades are wet, the fertilizer will stick and you will likely burn the blades. After broadcasting fertilizer use your hose or irrigation system to wash any fertilizer off the blades and down into the soil.

Two to three weeks after green up is a good time to address weeds in the lawn. If you want to use a weed and feed product, now would be a good time. You could also apply fertilizer and weed control as two separate practices.

For post-emerge broad leaf weed control you could use one of the 2,4-D blends. These products will not kill grasses, but will control many of the broadleaf weeds that are already growing. These blends can be purchased as retail products such as Bayer Advanced Southern Weed Killer, Trimec, Fertilome Weed Free Zone, and Ortho Weed-B-Gon. You will need to make applications when there is very little wind as these products will drift in the wind and impact off target plants in landscapes and vegetable gardens.

It is important to complete your weed control with these products by mid-May, before temperatures get to 90˚F. These 2,4-D blends can burn lawn grasses when temperatures rise, but we usually find the benefit greater than the damage up until about 90˚ F. You can use blends until the end of May in most years.

If you are having a lot of dollar weed problems, you can enhance the effectiveness of the 2,4-D blends by adding atrazine at the recommended rates in the same tank.

If one of your problem weeds is sticker weed, you need to get it under control before it flowers. If you delay, they will make seed for next year’s stickers and you will also have stickers that will prick your bare feet. We usually predict sticker’s flowering by April 15th.

For more information on these and related topics contact Kenny at 225-686-3020 or visit our website at

4/2/2018 7:27:03 PM
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