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How to Use Roundup Weed Killer

By S.F. Heron ; Updated September 21, 2017
Roundup helps remove nuisance weeds that grow in sidewalk and driveway cracks.
Window, Door and Weeds image by Scott Griessel from Fotolia.com

Roundup weed control products have become an essential tool in the gardener's arsenal against invasive plants. This product typically comes in a gallon jug container and features a tube attached to spray nozzle. This allows easy dispersion of the product onto nuisance plants. Learning how to use Roundup weed killer involves planning its application for the optimum time to kill weeds.

Select a day that features no chance of rain or wind. Even the slightest puff of wind can transfer sprayed weed killer onto nearby ornamental plants. Check the weather forecast when planning use of Roundup to ensure that a three- to four-day stretch of dry weather will allow complete penetration of the product.

Schedule spraying for moderate temperature. The effectiveness of Roundup decreases with very low or high temperatures. Choose a day for application with mild temperatures in the 65 to 75 degree F range. Applying herbicide on hot days causes quick evaporation of the weed killer from plant leaves.

Make sure you do not apply this product on plants near a water garden or pond. Roundup is toxic to aquatic animals such as snails, fish and toads. The main ingredient of glyphosate in Roundup doesn't appear to affect frogs, snails and other land wildlife but the inactive ingredients are harmful to these animals, according to research performed at Duke University. Use this product sparingly to limit damage to local wildlife.

Wear protective clothing and eyewear to cover all exposed surfaces of the skin. Completely read all directions listed on the back of the Roundup container.

Pump the sprayer if necessary and place the spray nozzle 4 to 6 inches from the weed leaf. Spray a stream onto the leaf surface to thoroughly soak it. Don't spray the stem or soil around the weed. Leaves absorb the glyphosate and will kill the weed within seven to 10 days.

Avoid spraying weed killer in areas near desirable plants. It's impossible to completely limit overspray or splashing when dispensing spray weed killers. Hand pull or cultivate the soil in these areas for easier weed removal. Cover treasured plants with an upturned bucket for further protection during spraying.

Wait one week and gauge the response of the weeds. Herbicides react differently depending on the maturity of the weed and weather conditions. Apply a second application for the more stubborn weeds.


Things You Will Need

  • Roundup weed killer
  • Plastic gloves
  • Protective eyewear
  • Protective clothing