Roundup is one of the most common weed killers used to control unwanted grass and weeds in lawns and gardens. The herbicide quickly eliminates common weeds like dandelions and clover, but can harm other plants if not used correctly. Follow a few simple instructions to use Roundup weed killer safely and effectively.
Don't use Roundup on windy days or when rain is forecast. The wind can spread the herbicide to other plants. If it rains within six hours of applying Roundup, you will need a second application. Roundup works best on mild days when the temperature is between 10 and 25 degrees Celsius.
Prepare the sprayer. Roundup comes in Pull & Spray bottles and 1.33 gallon Pump 'N Go Sprayers. If using the Pump 'N Go Sprayer, connect the hose to the container and extend the wand. Pump 15-20 times to increase pressure. This should give you five minutes of continuous spray in when depressing the button on the wand.
Spray the entire leaf of the unwanted plants while avoiding excess run off. Roundup works best in the spring and summer, when leaves are still growing. Use on patios, driveways, along fences. Roundup is safe to use in vegetable gardens, but it kills all vegetation, so spray only the weeds.
Release pressure in the Pump 'N Go Sprayer by pushing down the handle while turning it counterclockwise. Retighten the seal when the handle is all the way down. Store Roundup weed killer for up to four years.
Wait 24 hours after application of Roundup to plant flowers, trees and shrubs. You can safely plant grass, vegetable plants and herbs three days after application.