Get out of the weeds with smart use of herbicides
Gardeners, in general, are a pretty laid-back group of folks that research shows tend to be happier due to all of that fresh air and communing with nature. Call it mindfulness even. However, one thing that can drive a happy gardener mad is weeds.
Homeowners, whether they consider themselves gardeners or not, also struggle with weeds coming up in flower beds and the lawn. When dealing with any problem around the home and garden, having a good toolkit and knowing which tool to use for the right job is important. One of the tools available against some of our problematic weeds in the lawn and garden are the group of herbicides known as pre-emergent herbicides.
The best form of weed control in the lawn is a thick cover of healthy grass. In garden beds, the use of mulch (research shows that the chunky pine bark mulch is best) and keeping the beds full of properly placed perennials helps keep weeds at a minimum. And let’s just remember that we aren’t going to eliminate weeds; we just want to keep them to a tolerable level.
So, before you go running for an herbicide to solve all of your weed woes, remember that it will take all available tools, including hand pulling, to get weeds under control.
How to use pre-emergent herbicides
Pre-emergent herbicides, generally, are in a group of herbicides that work by inhibiting root formation. Once watered in, they bind with soil particles to create a “barrier” of herbicide that germinating seeds sprout into and boom, bye, bye weed. Perennial plants, including your lawn grasses and flowering trees and shrubs are spared damage because most of their roots are beyond this “barrier.”
It’s important to note here that preemergent herbicides are less effective in sandier soils and the topsoil layer should not be disturbed once the herbicide has been watered in as this can break the “barrier.”
Additionally, their ability to knock back weeds fades over time as sunlight, microbes, and water break them down. Therefore, follow-up applications may be needed for some late sprouting weed seeds.
Another important consideration is that the area can not be planted into, especially with seeds, for quite some time after application depending on the specific product. All of this information is provided on the product label, which should be carefully read before using and even before purchasing the product.
They won’t work on everything
With pre-emergent herbicides, there are some important factors that need to be considered before buying them and putting them out in the yard. First, they are primarily effective only against annual weeds. That means the tough perennial weeds, like nutgrass, dandelions, and clovers, won’t be much affected by them since their roots and storage organs (like the tubers of betony) are not near the “barrier” created in the upper soil layer. Pre-emergent herbicides can help block some seedy perennials, like wood sorrel, but their main target is annuals.
Maybe the most important consideration when using pre-emergent herbicides is the timing of application.
Since these products are only effective against germinating seeds, they must be applied prior to sprouting. So, if you can see the weed, it’s too late.
In the fall, these herbicides should be applied in October through November, when nighttime temperatures drop to 55 to 60 degrees Fahrenheit for several consecutive nights. In the spring, daytime temperatures of 65 to 70 degrees Fahrenheit trigger annual summer weeds to germinate, which typically occurs around late February. Again, these products break down in the soil and may take a follow up application, especially during the warm season to control hard to handle late germinators like doveweed and chamberbitter.
Identify your weeds
As for particular products, some preemergent herbicides work better on certain weeds. Therefore positively identifying weeds is important to better develop an effective plan.
Common products available in local garden centers include dithiopyr (sold as Dimension), isoxaben (sold as Gallery), and atrazine (sold under various brand names). As with any pesticide, always read the label before and after using to make sure you are protecting yourself and the environment.
As you find yourself dealing with plants in the wrong place, remember to use all tools at your disposal, including pre-emergent herbicides. They can be a handy addition to the weed control toolbox, but you will also need good oldfashioned hand pulling of weeds.
Don’t forget to do all you can to prevent weeds by keeping a thick, healthy turf cover and using a three-inch to fourinch mulch layer in flower beds, too. Also, try to reach garden transcendence by remembering that weeds are not going away for good and learn to tolerate some weeds in the landscape.