Weed Control in Lawns without using chemicals – Is it possible?

Author: Stefan Palm   Date Posted: 3 March 2021 

It’s a question we get asked regularly from people who have genuine concerns over whether off the shelf chemicals will have an effect on not only themselves, but wildlife, pets and livestock.

Many of the herbicides that you buy off the shelf in hardware stores and garden centres do have some undesirable side effects. While they will kill targeted weeds, they may effect aquatic life if the they get into water ways. Research suggests that some chemicals such as Dicamba (an active ingredient in some selective herbicides) can damage the roots of nearby trees and plants. Most of them instruct users to restrict access till the chemical has dried and others recommend that you don't feed clippings to live stock. When you start reading chemical labels, it's easy to understand why people want to consider alternatives.  

So the short answer to the question of whether chemical free weed control is possible, the answer is yes – mostly… There are many chemical free ways to kill off weeds and reduce weed populations – some very effective ones at that, however you'll need to be more tolerant of the odd weed and you'll also need to tip in more time to get rid of them.  Its also worth noting that there are some very persistent and hard to kill weeds that will require some extra special persistence or at least some initial chemical treatment to reduce the population to a point that they can be controlled without chemicals.   

Right at the top of the list when it comes maintaining a weed free lawn is ensuring your lawn is in top shape.  Lawn competition is one of the most effective non-herbicide weed control tactics available to the home gardener but in order for your lawn to out compete weeds, it will need to be healthy, strong and well established. This means paying particular attention to how you maintain it. While this may sound like a simplistic approach, its one that will most certainly keep weed populations down. Consider factors like:

  • pH – ensure the soil under your lawn is pH neutral. This is the sweet spot for lawns because this is where the lawn is able to extract all the available nutrients in the soil. A soil that is either too acidic or to alkaline will lock out nutrient resulting in a less than healthy lawn. The other consideration here is that there are weeds that prefer acidic soil and weeds that prefer alkaline soil so going too far in either direction will swing the pendulum in favour of the weeds over the lawn. pH can be measured using a pH test kit – if you find that your soil is acidic or alkaline, you can adjust it with garden lime or powdered sulphur
  • Fertilising. Weeds love soil that is low in fertility. Lawns do not love a soil that is low in fertility! It is essential that you maintain a programmed approach when fertilising your lawn to make sure that conditions favour a healthy lawn. I would suggest Paul Munns Year-Round Fertiliser Program.
  • Water management – Regular watering during the warmer months will help to keep your lawn in a healthy and strong condition. It doesn’t have to be excessive – but it does have to be consistent. The best advice I can give here is to water long enough to get moisture down to about 100mm below the surface at least once per week. You may need to apply a liquid wetting agent from time to time to make this possible as a large percentage of soils in Adelaide repel water instead of absorbing it. It makes sense that if you can get water down deep in your soil, then you can also make a way for lawn roots to grow down deep too. Deep roots generally equal a healthy and strong lawn.
  • Mowing. Keeping your lawn mown often will encourage it to spread and stay thick and dense. Regular mowing will also keep weeds from flowering and seeding. Its very important to not let weeds go to seed – as the saying goes: one year’s seeding is 7 years of weeding!

Ensuring your lawn is as healthy as possible will create an environment where your lawn will naturally suppress weeds however there still will be times when weeds germinate and grow. When that happens, there are some key things that you can do to control them.

Pay attention to weeds and manage weed populations before they get out of control. It’s much easier to tackle weeds when they young, small and few in number.  Removal techniques include the following:

Pull them out

Sure this sounds simple, but anyone who has tried to keep up with weeds by pulling them knows that it’s not always so easy – some weeds are more easily pulled than others. The best time to pull weeds is when the soil is still moist from watering or rain. Pull slowly from the base of the weed to get the best chance of pulling a root out and make sure to use garden gloves for spiny plants like thistles. There are some fairly nifty weed pullers worth investigating too – some of them can even be used while standing up such as the Fiskars Xact weed puller.  A word of advice, some weeds like creeping oxalis and clover have a runner type root system and can’t be pulled out easily.

Scald them

Boiling water is another alternative way to control weeds. This is a non selective method (ie boiling water will kill lawn too) so be careful how you apply the water. Simply pour boiling water from a kettle onto the weeds – the heat will destroy the cell structure in the leaves and kill them instantly.  Be careful of your hands and feet, and keep children and pets away.

Use a non-chemical weed killer

There are a new range of fatty acid based products being released that you can use to spot spray weeds in lawns. They are non selective (ie will kill lawn too) but they are a very effective control measure and are totally organic. Eco Organic have a product called Slasher that is certified organic. Click here for more info. 

The middle ground here is that you can manage weeds very effectively without chemicals in most situations however there may be circumstances where you need use chemicals to get on top of a persistent weed problem. It may be the case that you use chemicals to clean your lawn up, eliminating all the existing weeds and weed seeds, then move onto a chemical free program. I've written a few blogs lately on the use of pre emergent herbicides that work on killing weed seeds so that they don't germinate in your lawn. By using one of these (such as Embargo) you can clean up your lawn making it much easier to employ chemical free methods in the future - because from then on you will only be dealing with the odd weed or two rather than a persistant population In that way, while you would use some selective chemicals in the beginning, your use from then on would be minimal or non at all.  

It will mean more work. You may have to put up with some weeds but chemical free weed control is definitely possible.

Please feel free to leave a comment with your success stories on how you’ve managed weeds without using chemicals in your lawn.

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