Do You Need to Remove Weeds Before Laying Mulch?
If you're preparing your garden for mulch in Perth, one of the most common questions is: do you need to remove weeds before laying mulch?
The short answer is yes — for the best results, you should remove or treat existing weeds before spreading mulch.
A good layer of mulch can significantly suppress weed growth, retain soil moisture, protect your soil and improve the appearance of your garden. However, established weeds with strong root systems can sometimes grow straight through fresh mulch.
Taking a little extra time to prepare your garden before your mulch delivery arrives can mean fewer weeds and less garden maintenance later.
Here’s how to prepare your garden properly before laying mulch.
Should You Remove Weeds Before Mulching?
Yes. We recommend removing as many existing weeds as possible before laying mulch.
Mulch works particularly well as a weed suppressant because it reduces the amount of sunlight reaching the soil. This makes it more difficult for many weed seeds to germinate.
However, mulch doesn't necessarily kill weeds that are already established.
Strong weeds can continue growing underneath your mulch and eventually find their way through to the surface.
For the best results:
Remove existing weeds.
Remove as much of the root system as possible.
Prepare and level the garden bed.
Water the soil if necessary.
Apply mulch at an appropriate depth.
Starting with a clean garden bed gives your mulch the best chance of keeping future weed growth under control.
Can You Put Mulch Straight Over Weeds?
Technically, yes — but we generally wouldn't recommend simply covering an established weed problem with mulch.
Small or newly germinated weeds may struggle underneath a sufficiently thick layer of mulch, but established weeds can often continue growing.
If you've invested the time and money into having bulk mulch delivered, spending a little extra time preparing the area beforehand can make a big difference to the finished result.
Remember:
Mulch is excellent at suppressing weeds, but it isn't a guaranteed cure for weeds that are already established.
How Do You Prepare a Garden Before Laying Mulch?
Good garden preparation doesn't need to be complicated.
Start by pulling or removing existing weeds. Whenever possible, remove the roots rather than simply cutting the visible part of the weed off.
Once the weeds are removed, clear away unwanted debris and rake the garden bed relatively level.
If your soil is particularly dry, you can also give the area a good water before spreading your mulch.
This gives you a clean base before your new mulch goes down.
Should You Water Before or After Mulching?
If the soil is very dry, watering before laying mulch can be beneficial.
One of the major benefits of mulch — particularly during Perth's hot, dry summers — is its ability to help reduce moisture loss from the soil.
Watering the soil first and then applying mulch can help protect that moisture from evaporation.
You can continue watering your garden normally once the mulch has been spread.
Do You Need Weed Mat Under Mulch?
Not necessarily.
Many garden beds don't require weed mat underneath mulch.
An adequately deep layer of mulch can help suppress weeds naturally by reducing the amount of sunlight reaching the soil.
For organic mulches, skipping weed mat also allows the mulch to naturally break down and interact with the soil underneath.
There are landscaping situations where weed mat or another barrier may be appropriate, but it isn't automatically required every time you mulch a garden.
How Deep Should Mulch Be to Stop Weeds?
Mulch depth is one of the most important factors for effective weed suppression.
If your mulch layer is too thin, sunlight can still reach the soil and weeds may have a greater opportunity to grow.
For many garden and landscaping applications, approximately 75–100mm of mulch provides good coverage.
For example:
50mm: 1m³ covers approximately 20m²
75mm: 1m³ covers approximately 13.3m²
100mm: 1m³ covers approximately 10m²
The ideal depth will depend on your garden, plants, soil conditions and the type of mulch you're using.
Avoid piling mulch directly against tree trunks or plant stems. Leave some space around the base of plants rather than creating a mound against them.
Will Mulch Stop Weeds Completely?
No. Even correctly applied mulch won't guarantee a completely weed-free garden forever.
Weed seeds can enter garden beds through wind, birds, animals and surrounding vegetation. Over time, organic material can also accumulate on the surface of your mulch and create opportunities for new weeds to germinate.
However, a well-prepared garden bed combined with a good layer of mulch can significantly reduce weed growth and make your garden easier to maintain.
The occasional weed that does appear can often be easier to spot and remove before it becomes established.
What Is the Best Mulch for Weed Control?
The best mulch for your garden depends on several factors, including:
The appearance you want
How long you'd like the mulch to last
Your plants and garden type
Your budget
How quickly you'd like the mulch to break down
The size and scale of your landscaping project
At Murray River Mulch, we supply a range of bulk mulch in Perth, including:
Pure Grow Mulch – a versatile option for everyday garden and landscaping projects.
Premium Hardwood Mulch – ideal when you're looking for a premium finish.
Aged Arbor Mulch – a great option for garden beds and larger landscaping projects.
Chunky Landscaper Mulch – a coarser option suited to larger landscaping applications.
Not sure which mulch is right for your project? Compare our mulch products online before ordering or contact the Murray River Mulch team for help choosing the right product.
How Much Mulch Do I Need?
Before ordering your mulch delivery in Perth, measure the area you want to cover.
The basic calculation is:
Area in square metres × mulch depth in metres = cubic metres required
For example, if your garden is 100m² and you want to spread mulch approximately 75mm deep:
100m² × 0.075m = 7.5m³
So you'll need approximately 7.5 cubic metres of mulch.
Measuring your garden before ordering helps prevent ordering too little or ending up with significantly more mulch than you need.
You can also use the mulch calculator on the Murray River Mulch website to make working out your required quantity easier.
Bulk Mulch Delivery Across Perth
Once the weeds are gone and your garden is prepared, it's time for the easy part.
Murray River Mulch supplies and delivers bulk mulch across Perth and surrounding areas, with multiple mulch options available for gardens, landscaping projects and larger properties.
Ordering online means you can choose your product, calculate how much mulch you need, check your delivery area and organise your bulk mulch delivery in one place.
Whether you're refreshing an established garden bed, landscaping a new property or tackling a complete backyard renovation, preparing the area properly before mulching can help you achieve a better result.
The Bottom Line:
Remove Weeds Before Laying Mulch
So, do you need to remove weeds before laying mulch?
For the best result, yes.
Remove existing weeds and their roots where possible, prepare the soil and then apply your mulch at an appropriate depth.
Mulch won't guarantee that you'll never see another weed, but good preparation combined with adequate mulch coverage can significantly reduce weed growth while helping your garden retain moisture and protecting the soil underneath.
When your garden is ready, order bulk mulch online from Murray River Mulch and have it delivered directly to your property.
Frequently Asked Questions About Weeds and Mulch
Can I put mulch directly over weeds?
You can, but established weeds may continue growing through the mulch. Removing weeds before mulching generally provides a better long-term result.
Does mulch kill weeds?
Mulch primarily helps suppress weed growth by reducing the sunlight reaching the soil. It shouldn't be relied upon to kill established weeds.
How deep should mulch be to prevent weeds?
Around 75–100mm is a useful general guide for many garden and landscaping applications. The ideal depth can vary depending on the mulch, plants and conditions.
Do I need weed mat underneath mulch?
Not necessarily. Good garden preparation combined with an adequate mulch layer can provide effective weed suppression in many garden beds.
Should I water the garden before laying mulch?
If the soil is dry, watering before mulching can be beneficial. Mulch can then help reduce moisture loss from the soil.
How much area does 1m³ of mulch cover?
Approximately 20m² at 50mm deep, 13.3m² at 75mm deep or 10m² at 100mm deep.
Where can I buy bulk mulch in Perth?
Murray River Mulch supplies a range of bulk mulch products with delivery available across Perth and surrounding delivery areas. Customers can browse products, calculate quantities and order mulch online through the Murray River Mulch website.
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