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The Best Natural and Organic Weed Killers in Australia

If you’re not a fan of using too many chemicals in your garden, there are plenty of natural ways that you can control weeds.

While some of these methods require a little more work, others use common household products that you probably already have in your cupboard.

How to kill weeds naturally 

There are plenty of ways to you can control weeds naturally. All it takes is a little forethought and some time in the garden.

Dig weeds out by hand

Believe it or not, manual weeding is actually something I enjoy doing and I find it very satisfying. If you keep on top of the weeding regularly, you’ll soon find that it won’t take up too much time to rid your garden of pesky weeds.

The important thing to remember here is to dig out the weeds while they’re young and before they’ve had a chance to flower and go to seed. I also use a good weeding tool or garden knife in order to dig down below the roots and remove every part of the weed.

A trip to your local Bunnings or another hardware store will surprise you with the number of different weeding tools available. When armed with the right tools, weeding your garden by hand can be immensely satisfying.

Prevent weeds from growing by mulching your garden beds

As is the case with most things in life, prevention is better than cure. If you cover your garden beds with a thick layer of garden mulch, you’ll definitely have fewer weeds to worry about. And, those that do break through the surface, will be much easier to pull out.

The primary reason for this is that many weed seeds can survive in the soil for years and will germinate when exposed to moisture and sunlight.

By covering the soil with some good mulch, you’re effectively stopping the sun from reaching the soil. This means that the weed seeds won’t be able to germinate.

You can achieve the same effect by planting dense-growing groundcovers that will spread across your garden beds and keep the soil covered.

Use a flame burner

You might have heard about weed flaming. This method uses a gas-powered flame burner to heat up the plant tissue of the weeds to kill them. This can be quite effective and is relatively safe because it doesn’t use chemicals.

These weed burners are ideal for use on weeds on pathways, driveways, and garden beds that are not mulched. You have to be careful when using them around mulch and other dry organic material so that you don’t accidentally start a fire.

RELATED: Weeds With Yellow Flowers

Natural weed killers 

sprayer | Weed control

There are plenty of normal household products that can be used to kill weeds in your garden. Here are just a few to consider:

Use white vinegar and salt

For this method, you need to add one cup of normal cooking salt to one litre of white vinegar. Stir the mixture until the salt dissolves completely.

Apply this homemade weed killer to any actively growing weeds in your garden with a small paintbrush. You have to be careful not to get any of it onto other plants because it will kill most things it comes into contact with.

Boiling water is great for killing weeds in paved areas

If you have weeds coming up through the gaps in your pavers or driveway, you can easily kill them just by using boiling water.

Just make sure that you don’t get any on your prized plants.

Use vegetable oil on bulbous weeds

Tough-to-remove weeds like oxalis and onion weed can be controlled using vegetable oil.

What you need to do is carefully inject the oil into the soil around the bulbs. This causes them to suffocate and die.

Make sure that you don’t get the oil onto any roots of living plants that you want to keep because it could suffocate those too.

Use iron sulphate to kill broadleaf weeds in your lawn

You can purchase iron sulphate at your local garden centre. It is commonly used as a plant nutrient but can be effective in burning broadleaf weeds in your lawn.

Mix two dessert spoons of iron sulphate into one litre of water in a watering can or sprayer unit. Spray this over your lawn where you have a problem with broadleaf weeds. 

Be aware though that this will leave some dead patches in the lawn until the grass has had time to regrow over those areas.

Slasher Organic Weedkiller

Slasher is an organic weed killer that kills weeds on contact. It works quickly and effectively and can be used anywhere in your garden or on paths and driveways.

This product does not contain glyphosate and is registered for use on organic farms and gardens. The active ingredient in Slasher is made from plant oils.

It’s 100% biodegradable within a few days, so there are no lasting spray residues.

How to prevent weeds from growing

mulch around plant | Weed control

One of the best ways to prevent weeds from growing is to cover the soil with organic mulch to a depth of at least 7 cm.

This effectively stops the sun from shining directly on the soil and stops weed seeds from germinating.

Other methods include:

Using solarisation for a new garden bed

If you’re preparing a new garden bed for planting, you can destroy all the weeds growing there by using solarisation.

Using a large sheet of clear plastic, cover the area entirely. Remember to secure the edges of the plastic so that it won’t blow away.

Then, just let the sun do the work for you. You need to allow at least 8 weeks for the sun to completely cook the weeds. If enough heat is produced, this method should also kill the weed seeds that are dormant in the soil.

Use the sheet composting method on a new garden bed

Another way that you can create a weed-free garden bed is to use the sheet composting method.

Bear in mind though, that you’ll have to prepare the garden bed at least 3 to 6 months before you want to plant it.

Here’s what to do:

  • Water the soil well
  • Cover the soil with six layers of newspaper or cardboard
  • Place organic mulch over the paper to a depth of 10 cm
  • Sprinkle some blood and bone over the mulch as this will activate decomposition
  • Water again

Let the bed sit for around 3 to 6 months without doing any digging.

This will give you an entirely weed-free garden bed to grow your vegetables, flowers, or ornamentals.

Weed mats / landscaping fabric

A weed mat is a fabric barrier designed to prevent weeds from growing and spreading.

It’s an alternative to herbicides and other chemical-based weed control products, and is a popular option for those seeking sustainable solutions for weed control.

Weed mats work by blocking sunlight, smothering and preventing weed seeds from growing. If you use a weed mat product correctly, it can reduce weeds by up to 90%.

The downside of weed mats is that they can stop moisture from getting through to the soil below. Also, many people don’t like the idea of laying plastic in their garden.

Fortunately, there are numerous weed mat alternatives that you can use to help suppress the weeds and still have a lovely healthy garden with soil that is enriched and full of goodness.

These include mulch, newspaper or cardboard, and ground cover plants.

FAQ

Will grass grow back after contact with vinegar?

Yes, as long as the grass roots are well developed, you’ll find that the grass will grow back if you’ve accidentally killed some with vinegar.

Is pulling weeds a waste of time?

Pulling weeds is not a waste of time if you get them while they’re still young and haven’t gone to seed yet. The more you pull consistently, the less you’ll have in the long run.

Does mowing weeds spread them?

This depends on the type of weeds and whether they’ve developed seed heads. If the latter is true, mowing will definitely spread the weeds because the grass clippings will contain weed seeds that will germinate and grow again.

Photo of author

Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.

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