How a Pre-Emergent Herbicide Works
This type of herbicide is used early in the growing season and prevents seeds from germinating as the weather becomes warmer in the spring. The herbicide creates a barrier and seal around the seed, making it impossible for the seed to sprout and a new plant to grow. It is important not to aerate after applying the herbicide because aeration can break the seal around the seed. If you decide to aerate your lawn, complete the process before using a pre-emergent herbicide.
Contrary to popular belief, pre-emergent weed killers don't destroy weeds and their seeds. They simply stop them from growing. Some seeds are known to last fifty years, so if the herbicide isn't applied each year, the weed will grow.
Apply pre-emergence twice yearly, the two dates to remember are March 15 and September 15. Those are the two dates of the year around which pre-emergent fertilizers should be applied so that they activate before seasonal weeds make an appearance.
Two Weed Growth Periods In Some Regions There are two application dates because generally there are two types of weeds, winter weeds and summer weeds. This is especially true in regions that don't freeze over in the winter.
Here are the basics:
- Our company will come to your home shortly after contacted and provide a professional service that includes both pre and post emergent to your home.
- Pre-emergent will kill off the seed underground before they turn into weeds.
- Post-emergent will burn current weeds that are already showing up in your yard.
- We recommend for this to be done to your home twice a year. The first time being now, during the fall season, the second time in the spring.
The summer weed date is March 15th, because that is usually when average soil temperatures reach above 50 degrees. Major summer weeds like crabgrass or clover will only emerge once the soil is consistently over this temperature. In warmer areas, the date will probably be earlier.
The September 15th date is to catch weeds as they set new seed. This fall application will limit any late fall growth and hopefully begin weeding work for next year.
If you use a pre-emergent herbicide, keeping these two dates in mind can help you get a head start in weed control.
If you missed the window of opportunity for applying a pre-emergent herbicide, you can apply a post-emergent product. Post-emergents work by destroying already established weeds. However, take care when applying post-emergent herbicides. Some are selective, meaning they target specific weeds, while others are nonselective, which means they destroy anything and everything green, whether they're weeds, your grass, flowers or shrubs. Therefore read the product label.
Keep in mind that you'll never get rid of all the weeds in your lawn. The wind will blow weed seeds from nearby lawns into your lawn, birds will deposit them and kids running from one lawn to the next will transport weed seeds on their shoes. So do what you feel you must to battle the weeds in your lawn, but do it wisely. Paul recommends using natural pre-emergent herbicides made from corn gluten or natural post-emergents made from vinegar or clove oil. Raise the height of your mower to help prevent weed seeds from germinating in the first place. Fertilize twice a year with a natural product to promote vigorous grass.