Ironweeds are perennial plants that are found in tropical areas and are native to North America. These plants can grow as tall as 3 to 10 feet and are considered one of the most common weeds found in pastures. Although they are pretty plants with their purple flowers that add a splash of color to your field, their invasiveness makes them troublesome and they are also known to reduce grazing as animals avoid this particular type of weed. Thus, the need arises to control ironweed plants in pastures and inhibit their growth as much as possible. 

Before we move on to the mechanical and chemical means of ironweed plant control, let’s learn about it a little more and why are they considered bad for your pastures. 

About Ironweed Plant

Ironweed plants, as stated above, are found commonly in the United States. These plants although provide beautiful scenery for your pastures, but take up space for desirable plants that animals can eat. That doesn’t mean that ironweed plants are dangerous to an animal’s health but the intake of a large amount could lead to a problem.

Although, ironweed plants serve us greatly as ornamental plants and can easily attract bees and butterflies over. A mature and tall ironweed plant can produce around 14,000 seeds in a single season, and thus they can gradually cover up a large area of your pastures and take over space for preferred plants. Ironweed plants also have an extensive root system, thus they can survive even in the harshest conditions, and hand-pulling them out might be effective but simply not possible. Thus, if left unattended, ironweed plant control would be difficult.

The only way to get rid of these weeds is by treating them before they are matured and prevent their growth. Thus, the timings of the treatments are crucial for ironweed plant control.  

How to Control Ironweed Plants

Since these weeds are tough to get rid of, a combination of treatments is best to hinder their growth. There are mainly two ways to control ironweed plants, mechanical and chemical, let’s see what they are. 

  • Mechanical Control

Mechanical control involves mowing your pastures periodically to control the growth of ironweed plants. It has been researched that mowing in early May and then re-mowing the plants when the height reaches 6 to 8 inches could result in a subsequent decline in their population, around 80-90%. Keep in mind that factors like environmental conditions, mowing date and time, and the number of mowings can affect the control of ironweed plants. 

Tired of brambles? Here is how to prevent them effectively.

  • Chemical Control

Ironweed plants cannot be controlled by mowing. For more effective control, it is recommended to use herbicides once or twice a year to prevent regrowth. One of the most effective herbicides is Glyphosate applications. It is only effective for plants that are growing in good conditions and are healthy. It is recommended to treat plants with herbicides from late May to August. Once they are regrown after being mowed, so the newer leaves and stems are more susceptible to the applications. Although, Glyphosate can only be used in spot applications as its harmful for other desirable plants as well.

Other herbicides application for tall ironweed plants include ingredients: triclopyr, dicamba, and 2,4-D. 

Check: Creeping Charlie Killers for Weed


The only way to control tough weeds like ironweed plants in your pastures is by identifying them, mowing them, applying herbicide treatments, and being consistent. These are pesky weeds with extensive rooting systems, thus spot treatments can only do so much. A combination of treatments done periodically could help you control the ironweed population greatly, just be persistent, and be careful to not damage clover or other plants. 

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