Post-emergent herbicides are instrumental in knocking out those pesky weeds once they’ve surfaced in the spring. Once those summer weeds become established, they produce seeds to perpetuate the species. It can become a vicious cycle of spraying trying to get ahead of the weeds. Post-emergent herbicides work by killing growing plants, usually by interrupting chemical processes such as photosynthesis, protein production, or root growth. They are best applied when the plant is actively growing. This allows the herbicide to be quickly drawn down into the roots where it is most effective. Post-emergent herbicides can work on contact (killing only the vegetation they touch) or systemic (absorbing into and killing the entire plant). However, there is a better way.
Have you spent countless hours pulling weeds by hand, or repetitively spraying weed killers? We all hope for a better way to improve the appearance of our lawns.
Welcome your new best friend; Pre-emergent herbicides. Pre-emergents are group of garden products that offer a relief from that aggravating problem. No, they do not offer automatic salvation as in ‘use once and forget about it’. But they are one of the most important weapons in a gardener’s arsenal.
Pre-emergent herbicides attack weed seeds as they begin to germinate by killing the immature root as they emerge from the seed. This means you interrupt the growing process before weeds even become visible. With pre-emergents, you are taking preventative measures for a weed free yard. Application timing is critical to have optimal results. Most pre-emergent herbicides have about a90 day residual. By allowing gaps in the coverage, you may allow seeds to germinate and start the cycle all over again.
In the Mid-South, we have a unique situation. Although we live in the south where winters are supposed to be mild, we have had some pretty cold winters. In the north, where you can almost be certain that it will remain cold all through winter, an application of pre-emergent is not necessary. However, here in the mid South, where the weather can go from cold and rainy to sunny and warm, a winter application of pre-emergent can help eliminate the weeds we see when the sun comes out and the temperatures rise during the winter months. Generally, a pre-emergent is applied in the late summer to early fall (usually mid-September to early October), but Mother Nature does not always follow the calendar so give us a call if you have any questions.
This first application is to control early germinating poa annua and other winter weeds. Your next application, put down between 80 to 90 days after the initial application, will help stop other cool season weeds and more poa annua. Your third application, and probably the most important, will be 80-to 90 days after your winter application. This will help stop the broad leaf weeds and most importantly crabgrass from taking over your lawn. Crabgrass in particular, is a very invasive grassy weed that is difficult to eliminate in your yard using weed killers. Post-emergent non-selective weed killers will kill crabgrass, but it will also kill the surrounding lawn you are trying to protect. Selective weed killers will help to eliminate existing crabgrass, but does nothing to stop future generations from germinating and growing right back where you just sprayed. Crabgrass produces a toxic chemical that inhibits the growth of plants around it, so once entrenched; it will soon start affecting your entire lawn. One single clump of crabgrass can produce over 100,000 seeds during a typical growing season. These seeds are spread every time we cut the lawn. Bagging helps, but is not the answer.
Hi-Yield Turf & Ornamental Weed and Grass Stopper containing Dimension provides superior control of crabgrass as well as control or suppression of other listed weeds when applied before they germinate. This will also provide post-emergent control of crabgrass and is effective on crabgrass up to 4 weeks after it has germinated. Hi-Yield Turf & Ornamental Weed and Grass Stopper can be applied to both warm and cool season grasses and unlike most other brands on the market, can be used in your flower bed and other landscape areas, as long as you do not plan to plant seeds in those beds. If you plant a fescue grass yard or plan to over-seed your Bermuda or Zoysia lawn, take great care in using pre-emergent prior to seed planting. Remember, pre-emergent can have up to a 120 day residual and will impede the germination of your grass seed. It is also best to wait to use pre-emergent on new lawns. Allow your grass to become well established allowing for adequate root growth before treating with any chemicals.
So far I have only mentioned a fall, winter, and spring application. What about summer?
As with anything else in life, too much of a good thing is not good for you. By constantly bombarding your lawn with the same chemicals, root damage can occur. We recommend that you give your yard a rest during the peak growing season and either pull or use a post emergent type weed killer for the few weeds you may see throughout the summer. Use the summer months to enhance the soil and treat your lawn with products that will make both the grass and soil healthier.
Conquering a weedy lawn is quite a challenge. However, you can be successful if you keep one thing in mind: weeds are a signal that the grass in your yard isn’t happy. A healthy, thick lawn will naturally be low in weeds. Use pre emergent to stop weeds before they start. Use organic lawn foods to feed not only the plant, but the soil also. Water deeply to allow for healthier root growth, and give your yard a hot summer treat by spraying with liquid seaweed or fish emulsion. It may take a little time to get your yard back, but once you do, you will be the envy of the neighborhood.