In II Corinthians, Paul talks about enduring a “thorn in his side”. While no one knows exactly what the thorn was, most agree that God gave it to Paul so that, despite his many blessings, he would not become too prideful in his faith. That story comforts me because each year the Lord “blesses” me with some new gardening “thorn” that keeps me humble about my garden and my gardening abilities. This year, my thorn came in the form of a beautiful (but noxious) vining plant called purple bindweed! While the flowers of this noxious weed are truly beautiful, that beauty does not make up for the overall nastiness of this weed.
Purple bindweed is a native Texas morning glory. It is also an aggressive vining plant that will literally grow over anything in its path. One plant can send out trailing, twisting vines that stretch out over 15 feet. While I have to admit, when those vines cover a fence and explode with flowers, the effect is very beautiful. However, when they creep up your sugar cane or get twisted in with cucumbers and cantaloupes, the effect is not so nice.
Even though this plant is literally driving me crazy, I have to admire its shear survivability. Each plant can produce 500 or more seeds. The seeds have a very thick seed coat that can lay dormant in the soil for 20 years (some say 50 years or more). The plant develops an extensive root system that can grow 10 feet or more into the soil. Because of this, you can pull it, dig it or plow it and it will still come back. In fact, research shows that a 2” piece of root can produce a new plant. In addition, all of those deep roots make this plant very drought resistant.
All of the survival traits that the plant has developed make it very hard to control organically. The only real option you have is frequent pulling or smothering. If you decide to pull, realize that you will need to pull every shoot that pops up every three weeks or so for the next three years! If you want to try and smother it you are going to need to use something like a large sheet of plywood or hardi-plank and you are going to have to leave it in place for years. However, since the seeds can remain dormant for years, smothering and pulling is really only going to slow down the spread of this weed.
The only way to effectively kill bindweed is with an herbicide. Even though I do not personally like chemicals, the reality is that some weeds will never be fully contained with organic methods. If you don’t mind spraying chemicals try Glyphosate (Round Up) or Tripcloyr (Remedy). Both work well against bindweed. For the best effect, many recommend mixing up a combination of both Glyphosate (2-3%) and Remedy / Triclopyr (0.25%). These chemicals will definitely kill the bindweed if you spray it while the plant is actively growing. For bindweed, the absolute best time to spray is when it is blooming. NOTE: These chemicals will definitely kill the bindweed. Unfortunately they will also kill just about everything else that is actively growing. Be careful to avoid overspray when applying this (or any) herbicide. Also, apply just enough herbicide to wet the leaves. There is no need to soak the plant. There is also no benefit to mixing them in higher concentrations than are listed on the label.
The purple bindweed is beginning to bloom at my house. This means that despite my best organic control efforts, it has beaten me. This “thorn in my side” is one of just a few plants that have made me question my commitment to organic control methods. Thank goodness I have St. Paul for inspiration. Although his “thorn” tormented him his whole life he persevered; and so will I. However, I have to admit, when I am out there pulling this weed in the Texas heat the thought of spraying it with an herbicide is very tempting!