Spring Lawn Fertilizers

Every spring, at this time of the year, we get lots of calls on lawns. Most people want to fertilize and also apply a herbicide at the same time. This is easily done with the weed and feed fertilizers. The following article from Dr. Ron Strahan will give you a guide to properly using weed and feed fertilizers.

When do we fertilize or use weed and feed in St. Augustine grass and Centipede grass?

With the warm weather, I am sure homeowners are anxious to fertilize their St. Augustine grass and centipede grass as well as get weed and feed out on their weeds. However, it is not time to put either conventional lawn fertilizer or weed and feed out on St. Augustine grass or centipede grass right now. Fertilizing this early with high nitrogen lawn fertilizer or weed and feed can contribute to winter kill with a late season freeze and bring on brown patch disease.

The best time to apply weed and feed in St. Augustine grass and centipede grass is to make them your first application of fertilizer. Timing the first fertilizer application or weed and feed depends on where you are located in the state. Here in Southwest La. the best time to make the first fertilizer application or put out weed and feed in Louisiana in St. Augustine and centipede grass lawns is late March or early April.

First Fertilizer or Weed & Feed Applications for St. Augustinegrass and Centipedegrass in Louisiana

Area of the State

Application Dates

New Orleans

Late March

Baton Rouge/Lake Charles/Lafayette

Late March / Early April


Early April



How well do weed and feeds control weeds?

Weed and feeds are not always the most effective weed killers but they are definitely the most convenient to apply since you can use a fertilizer spreader and cover large lawns quickly.

Overall, granular weed and feed performance has not been as good in my field trials as spraying liquid atrazine (best on winter weeds) or Weed Free Zone, Weed B Gon, Trimec (all 2,4-D/dicamba based products). Homeowners are going to use weed & feed products so they might as well apply them properly and time them correctly.

How do we use weed and feed?

No doubt, homeowners like to use weed and feed products like Scotts Bonus S (atrazine) or some type of granular “trimec” herbicide (2,4-D, dicamba, mecoprop) for their winter weed problems. Most weed and feed herbicides have the herbicides impregnated on a very high nitrogen fertilizer granule. It is ok to recommend them but let your clientele know the proper time and way to use the products.

  • If it is an atrazine based weed and feed like Scotts Bonus S (usually will say for St. Augustine grass and centipedegrass), water in after application. Atrazine works mainly through root uptake so watering after spreading gets the herbicide into the root zone.
  • If the weed and feed contains Trimec, it should be applied when there is a heavy dew or after the lawn has been irrigated. The granules need to stick to the weeds for the herbicide to work with “Trimec” type weed and feeds.

Both weed and feed types will tell you to stay away from the drip line/root zone of trees and shrubs.

For more information come by or call us at 337-788-8821.

3/11/2011 1:33:09 AM
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