Killing Weeds in the Lawn is not as Simple as the Label Portrays
Weed killers – aka herbicides - are not some “smart chemical” that seek and permanently destroy only weeds without killing the lawn. “Herb” is Latin for plant and “cide” is Latin for killer - herbicides are plant killers and turfgrass is a plant. Applying too little will give no results, apply too much and you may get too many results – a dead lawn.
Killing Weeds in a Lawn Requires a lot of Knowledge and Experience
The variables that you must consider before applying an herbicide are legion: species, growth stage, season, temperature, humidity, soil temperatures, herbicide mode of action, effects on desirable species yada, yada, yada. In addition, you can only use the herbicide as directed by the label. The bottom line is that killing weeds without killing a lawn requires a lot of knowledge and experience.
Weeds are not the End of Your Lawn
Weeds are not lethal – weeds do not kill your lawn, choke out your lawn or destroy your lawn. Poor irrigation, low mowing, and chinch bugs will damage or kill your lawn allowing weeds to invade a healthy lawn. Tuf Tip: Focus more on keeping your lawn healthy and less on getting rid of weeds and you will achieve both.
Best Weed Control: A Holistic Approach
Weed control in a lawn requires a very holistic approach. Most homeowners believe that if they just kill the weeds, their lawn will be beautiful again. But it won’t. A beautiful lawn isn’t beautiful because it has few weeds, it is beautiful because it is thick and healthy. A thick thriving healthy lawn has few (if any) weeds. Therefore, the best way to control weeds in your lawn is to control the health of your lawn.
Weeds Repopulate Your Lawn Because They Can
Weed seeds are everywhere and most are lying dormant waiting to sprout and repopulate your lawn. The constant effort by weeds to repopulate your lawn is what nature does best and is unstoppable. When conditions are right for weeds to grow and thrive, the weeds will sprout. The best weed control is a thick healthy lawn. A healthy lawn is constantly counteracting the constant efforts of weeds to repopulate your lawn.
Tall Thick Canopy of St Augustine Turf Grass Prevents Weeds from Sprouting
Many of the right conditions for weeds already exist in the lawn – soil, moisture, fertility and weed seeds. However, the tall thick canopy of a healthy St Augustine turfgrass lawn eliminates one important condition – sunlight. Even if a weed sprouts, it will likely run out of energy before it escapes above the tall canopy. And should it emerge above the canopy it is already stressed and will likely perish in the hot Florida sun. Should it manage to survive, a dose of herbicide will further stress it to the point of failure.
The Opposite is True – An Unhealthy Lawn is the Right Condition for Weeds
Since many of the right conditions for weeds already exist in the lawn, if you eliminate the tall thick canopy, every weed seed will sprout, grow and thrive. For example: Imagine a healthy St Augustine turfgrass lawn that is nearly weed-free. Chinch bugs kill a part of the lawn. Soon weeds, like crabgrass and spurges, sprout, grow and thrive. You blast them with “Weed Killer for Lawns” and soon you have the same weeds again. You rinse and repeat but weeds return. Why? No healthy lawn to stop nature from doing what nature does best – grow weeds.
Weed Science Fact: A Healthy Lawn is Your Best Herbicide
A thriving St Augustine turfgrass lawn is the best herbicide. Not only does it reduce weeds it also stresses weeds so that chemical herbicides can be more effective at smaller doses. For the DIY’er, your best herbicide is a good irrigation system and mowing the lawn at 3” or above. Then if you do have a few weeds break through the canopy, the “Weed Killer for Lawns” can help. But without the healthy St Augustine turfgrass lawn, it is a hamster wheel of lawn care – spray weeds, weeds die, weeds return.
When to Use Herbicides
There are some weeds that are difficult to control even in healthy St Augustine turf grass lawns – sedges, dayflower and dollar weed are the top offenders. Keeping these offenders out of sight requires a healthy lawn to keep the weeds under stress and frequent applications of herbicides to knock them out. For lawns with sedges, dayflower and dollar weed, it may be wise to hire a professional to keep your lawn healthy and the weeds stressed.