10 April 2023
Lawn landscaping has two ends of the spectrum. On one side are those that feel grass is no longer relevant and the yard should be filled with edibles and native plants. The other opinion is that the homeowner should maintain carefully manicured turf to present a clean and well kept neighborhood. It is quite unfortunate when these two ideologies live next door to each other.
For those who want their landscaping to look like a golf course, there is an opportunity to control the aggressive spread of some of those native plants that can be considered weeds. That is the application of a pre-emergent, also known as crabgrass preventers.
A pre-emergent will not affect any existing plants in the ground, nor will it kill any seeds that may already be there or prevent them from germinating. However, it will be a preventive from any new seed that tries to establish a foothold. So, any existing unwanted plants would need to be treated by conventional methods and any of those seeds already in place before the pre-emergent was applied, will need to be dealt with as you see fit.
Most commercial preventers will last about two months. The natural microorganisms that live in the soil will break down the chemicals. That makes it a guessing game about when to apply the product. If you apply it too early, you will need to go through the process again late summer. However, if you wait, you take the risk of early germination of your neighbors’ plants and then having the wind share those seeds with your yard.
There are two products that will last the entire season, Dimension and Barricade. Products that contain pendimethalin will need a repeat after about eight weeks. Because they are long lasting, Dimension and Barricade can be applied early in April and Barricade can even be used in the late fall to control crabgrass for the next year.
Make sure the application is spread evenly. If an area is left untreated, you will see weeds where you don’t want them. Calibrate your spreader per the package directions. If you are uncertain about how to operate the spreader, check with the manufacturer. Apply the product on a day with a little wind as possible.
After the pre-emergent herbicide has been applied, gently water the entire area. Some people think it is a good idea to put down the pre-emergent just before a rain. That is fine if you are positive that you will get the blessing from the sky and it will only be a gentle sprinkle. If you get no moisture, then your time and money have been wasted because the chemicals will not be activated. If you end up with a heavy rain or thunderstorm, it will wash away most of the product.
If you plan to overseed or reseed your lawn, wait at least two weeks.
Since these herbicides have no effect on existing plants, you should be fine with the current flower beds. If you have any concerns, it is suggested that you place a canopy over areas that may be ready to drop seeds.
One of the best protectors against weeds is simply a healthy lawn. A full, tight turf that is absorbing the proper nutrients leaves less space for the weed seeds to find a place to settle and grow.