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Lawn & Garden

Apply Pre-Emergent To Prevent Weeds


Pre-emergent is a mild herbicide that effectively controls weeds without endangering plants that already have an existing root system. It kills germinating weeds before they can develop their roots.

Using weed preventer will greatly reduce the need for post emergent weed killer. No method of weed control is totally effective, but prevention is a less toxic approach and the most effective way to improve your lawn.

The Right Time to Apply

Winter is the best time to apply pre-emergent weed preventer, but it is not the only time. Pre-emergent will protect for up to three months, depending on rain conditions and soil type.  Scott’s Halts and Spectracide WeedStop are examples of pre-emergent herbicides that use different active ingredients. Scott’s Bonus-S has both preventative and post-emergent action. Apply no more than two applications per year of any particular herbicide.

Select the Correct Herbicide

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The selective herbicide that is utilized in Bonus-S is intended for use in lawns that are prevalent in the southernmost regions of the United States. It also targets many of the common weeds that grow in that area. Other lawn grasses, such as Bermuda and Fescue grass could be damaged when exposed to the atrazine that is in Bonus-S. No not use Bonus-S in Bermuda or Fescue lawns.  Bonus-S is only for use on St. Augustinegrass (including Floratam), zoysia, centipede, and carpetgrass lawns.


Pre-emergent is available in combination with fertilizer for use in lawns that do not go dormant. Frost free regions have grass growth all year long, but grasses will go dormant to survive freezing temperatures in areas to the north. If your lawn is dormant, avoid applying nitrogen to it. Choose your weed preventer without nitrogen during the dormant season.

How to Apply Pre-Emergent

Apply pre-emergent to a dry lawn and water it in afterwards. A vapor barrier is formed at the soil surface that will deter the germination of seeds where the product was placed for about 3 months. It works best if the soil is left undisturbed. If the soil is cultivated during this time, re-apply the pre-emergent afterward.


For areas that you plan to add seed, avoid pre-emergent for 4 months before you seed those areas. Pre-emergent will prevent lawn grass seeds from germinating, just like it does for weeds, but grasses that grow from rhizomes and established root systems can successfully grow through the pre-emergent’s protective layer.

Click here to learn How to Apply Post-Emergent To Kill Actively Growing Weeds.

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Posted 2016-01-15T14:28:51+0000  by Travis_HD_ATL Travis_HD_ATL