How to Use Herbicides


Though many gardeners may always be looking at ways to create and cultivate life, there are some lifeforms that nearly all gardeners hate. Invasive plant species, also known as weeds, tend to creep up where they are most inconvenient and unsightly. In some cases, that's all they are. In others, they can choke out the desired species and become a much larger problem. While there are many different methods of treating invasive species, using a herbicide may be one of the most convenient and effective.

Step 1

Identify the plant if possible. Identifying the invasive plant species you wish to eradicate can be very helpful when choosing what type of herbicide to use. Some may be more effective than others, depending on the plant species.

Step 2

Choose a preemergent or postemergent herbicide. A preemergent herbicide prevents seeds from germinating, hopefully stopping the problem before it starts and leaving existing plants unharmed, in most cases. A postemergent herbicide is just the opposite, killing plants that have already sprouted and grown.

Step 3

Wait until the proper time. This is especially important if using a preemergent herbicide to control annuals. Find out when the seeds begin to germinate and apply a preemergent herbicide within 30 days of that time period. Doing it much further in advance could be mostly ineffective, as these herbicides tend to break down in approximately 30 days to allow planting of desired species. Waiting until later means it will not be effective against existing plants.

Step 4

Mix the herbicide, if necessary. There are two types of herbicides---those that come ready to spray and those that come as concentrate. Follow all label directions and make sure you mix in a well-ventilated area.

Step 5

Spray the herbicide using a sprayer. The best ones to use are those that use pressure to provide a continuous stream. Otherwise, simple sprayers tend to give hand cramps, especially if you have a larger area to treat.

Step 6

Wait for results. Many herbicides are water activated. Therefore, a day after spraying you may want to sprinkle the treated area lightly or simply wait for the next rain, if you receive rain on a regular basis.

Tips and Warnings

  • Keep all unused herbicide away from children and in a ventilated area. Make sure you do not spray desired plant species or you run the risk of having to replant those species you are trying to protect.

Things You'll Need

  • Herbicide
  • Sprayer


  • Purdue Extension: Herbicides
  • University of Hawaii: Before you Buy or Apply a Herbicide
  • Dupage Turf: Dealing with Crabgrass

Who Can Help

  • Types of Herbicides
  • Organic and Chemical Herbicides
Keywords: preemergent herbicide, postemergent herbicide, invasive plant species, weeds

About this Author

Ken Black is a freelance writer and a staff writer for The Times Republican in Central Iowa. He has written extensively on a variety of topics, including business, politics, family life and travel.