How to spray weeds effectively

Author: Stefan Palm   Date Posted: 16 September 2020 

All proud lawn owners know that there are times of the year when uninvited weeds turn up and spoil the appearance of your lawn. You’ll also know that your efforts to control them can be hit and miss.

The same chemical, applied in the same way doesn’t necessarily achieve the same results. I’ve heard customers say time and time again that certain herbicides don’t work. While I understand the reasons people say this, I also know that there are many factors that determine how successful your efforts are. What can seem like random results are not as a result of the efficacy of the chemical but rather a bunch of other factors which can play havoc with how well they work. Let me explain.

Choose the right chemical

There are many chemicals that will selectively control weeds in lawn. The type you choose depends on the lawn you are spraying and the weeds you have in it. Typically, there are selective herbicides for winter grasses, summer grasses and broad leaf weeds. (click through for more info)  For example, if you choose a broadleaf herbicide and are targeting winter grass, you won’t get the results you are looking for. The other consideration is making sure you only apply the chemical to types of lawn listed on the pack. There are some chemicals that can only be sprayed on certain types of lawn. For example, if you apply weed and feed (containing dicamba) on a buffalo lawn, you’ll most likely kill it.

Use a wetter and spreader

This is an often overlooked step. Applying a wetter and spreader breaks down the surface tension of the droplets that come out of the sprayer. This ensures a more even and complete coverage of the weed ensuring better results. They also help the chemical to stick onto the weed. For tough weeds like creeping oxalis and clover, this is a critical step.

Read the instructions

It is critical to thoroughly read the instructions of the chemical you intend to use. While this may take a bit of time, it will give you a much better chance of success. You’ll also get some understanding of how to safely and effectively apply the chemical and what to do if you ingest any. Selective chemicals rely on being applied in an exact way. Often people think that if they use more chemical to make up stronger batches, they’ll get better results. This isn’t true. In fact, you’ll often do more damage than good. Stick to the recommended rates.

Choose the right weather conditions

Some chemicals will not work if exposed to dew, rain or water soon after application so make sure you time your application. Typically, you’ll need dry weather for at least 12 hours after application. In some instances, warmer weather provides more favourable conditions than cold weather.

Have the right spray equipment at hand

When spraying herbicides on lawn, the best way to do it is with a quality pressure or pump up sprayer. This will ensure even coverage.   

Don’t spot spray

I would recommend spraying your whole lawn rather than spot spraying if you have a heavy infestation of weeds. Spot spraying can lead to applying too much chemical on each weed and it can lead to only spraying part of the weed. Often creeping weeds can get quite large and it’s easy to miss parts of the weed if you’re spot spraying, leaving the missed parts to keep on living.

Be prepared to spray more than once.

If you have had weeds in your lawn for a while or if you have a significant infestation, you’ll most likely have to spray regularly to get rid of them. Don’t be surprised to see weeds persist beyond your initial spray. Vigilance is the key here – Keep spraying as required. Some weeds such as creeping oxalis will need to be sprayed every 2-3 weeks for an entire season to achieve control.

My only other advice would be to make sure you don’t spray within 7 days of mowing and secondly, be patient. Some weeds die quickly and others take a while. In some instances weeds can carry on as normal for up to two weeks after spraying before they start to die.


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