If you're thinking about putting mulch on your garden, there are probably a few questions you want answered first.
How deep should it be? How much do you need? Does mulch need replacing? Can you put new mulch over old mulch? And what's actually in arborist mulch?
We've put together some of the most common questions we get about garden mulch in Christchurch and Canterbury.
For more detailed information on individual topics, we've also linked to our other mulch guides throughout this article.
What Is Garden Mulch?
Mulch is material spread over the surface of the soil rather than dug through it.
There are many different types available, including bark, compost, straw and arborist wood chip mulch.
The arborist mulch we supply is made from tree and branch material processed through a wood chipper. This naturally creates a mixture of different-sized wood chips, bark and other woody material.
It is a different product from decorative bark because it isn't manufactured to be completely uniform in colour or chip size.
What Is Arborist Mulch Made From?
Arborist mulch is produced from material generated during tree pruning and removal work.
Depending on the trees that have been processed, a load can contain:
- Wood chips
- Bark
- Small pieces of branch
- Twigs
- Finer woody material
- Small amounts of leafy organic material
This variation is normal and is what gives arborist mulch its more natural, forest-floor appearance.
Is Arborist Mulch the Same as Bark?
No.
Decorative bark is generally produced specifically as a landscaping product and tends to have a more consistent appearance.
Arborist mulch contains a broader mixture of chipped tree material.
If your main priority is having perfectly uniform bark chips, decorative bark may be more suitable. If you're looking for an organic mulch for improving health of garden beds, trees and larger landscaped areas, arborist mulch can be a very good option.
What Are the Main Benefits of Garden Mulch?
A layer of organic mulch can help cover exposed soil, reduce moisture loss, suppress weed growth and add organic material as it breaks down.
Rather than covering all of those benefits again here, we've written a separate article explaining why garden mulch is useful in Canterbury.
How Deep Should Garden Mulch Be?
For most new garden beds, we generally recommend around 75–100mm of mulch.
An existing garden that already has a good mulch layer may only need a lighter top-up.
Depth matters because a very thin scattering of wood chips won't provide the same benifits as a proper mulch layer.
If you're starting a garden from scratch, read our guide explaining how to apply garden mulch correctly.
How Much Area Does 1m³ of Mulch Cover?
At a depth of 100mm:
1 cubic meter of mulch covers approximately 10 square meters.
As a quick guide:
- 2m³ covers approximately 20m²
- 4m³ covers approximately 40m²
- 6m³ covers approximately 60m²
- 8m³ covers approximately 80m²
If you're spreading it more thinly as a top-up, the same volume will cover a larger area.
How Do I Calculate How Much Mulch I Need?
You need two main measurements:
- The area of your garden in square meters.
- The depth you want to apply the mulch.
We've made this easier with our free garden mulch calculator.
Enter your garden measurements and preferred depth and the calculator will estimate the cubic meters required.
Can You Put New Mulch Over Old Mulch?
Yes.
Because organic mulch gradually breaks down, established garden beds can normally be topped up with another layer when the existing mulch becomes thin.
You don't need to remove all of the old material first.
Before adding more, check the existing depth so you don't accidentally build up an excessively thick layer.
How Often Should Garden Mulch Be Replaced?
There isn't a fixed schedule that suits every garden.
Organic mulch gradually breaks down and settles, so it's better to look at the actual depth than automatically replace it at a particular time.
If there is still a good mulch layer covering the soil, you may not need to do anything.
Once it has become noticeably thin, add enough new mulch to bring it back to the depth you want.
Does Mulch Completely Stop Weeds?
No mulch will permanently eliminate every weed.
A good mulch layer can make it considerably harder for many weeds to establish, but existing perennial weeds may still grow through.
For the best result, remove established weeds before laying a new layer of mulch.
Can I Put Mulch Straight Over Weeds?
You can, but simply burying large established weeds isn't usually the best approach.
Remove or control the main weeds first, then apply your mulch.
This gives the new mulch layer a much better starting point.
Do I Need Weed Mat Under Mulch?
Most gardens use organic mulch directly over the soil.
This also allows the lower mulch layer to gradually break down at the soil surface rather than being separated from it by a permanent barrier.
Whether weed mat is useful will depend on what you're trying to achieve and the type of area you're landscaping.
Should Mulch Be Mixed Into the Soil?
Arborist wood-chip mulch is generally intended to be used on top of the soil.
Spread it across the surface and allow the lower layers to naturally begin breaking down over time.
It doesn't need to be dug through your garden soil.
Does Mulch Break Down?
Yes.
Arborist mulch is organic material, so its appearance and texture will gradually change.
The lower material becomes finer as decomposition takes place, while the top layer remains more recognizable as wood chips for longer.
This is why an established mulched garden may eventually need another layer added on top.
How Long Does Mulch Last?
This can vary considerably.
How quickly mulch breaks down depends on the material itself, weather, moisture, garden conditions and how thickly it was originally applied.
Instead of worrying about an exact lifespan, periodically check your garden.
If you can easily see bare soil appearing through the mulch or the layer has become very thin, it's probably time for a top-up.
What Is the Difference Between Fresh and Aged Mulch?
Fresh arborist mulch has recently been chipped.
Aged mulch has been stored for a period of time, allowing the initial decomposition and settling process to begin before it reaches your garden.
At Canterbury Mulch Delivery, we age and regularly turn our arborist mulch for a minimum of eight weeks before delivery.
We've covered this subject separately in our full fresh mulch vs aged mulch comparison.
Can Mulch Be Used Around Trees?
Yes, but it needs to be placed correctly.
The main thing is to avoid piling mulch directly against the tree trunk.
We've got a separate article showing how to lay mulch around trees correctly.
That article covers mulch depth, trunk clearance and the root flare in more detail.
Should Mulch Touch Tree Trunks?
No.
Leave some clear space around the base of the trunk rather than piling mulch against the bark.
This is one reason you'll often hear people advised to avoid creating a deep "mulch volcano" around the base of a tree.
Our tree mulching guide explains this in more detail.
Can Mulch Be Used Around New Plants?
Yes, but don't bury the plant stems.
Spread mulch around the surrounding soil while leaving some clearance immediately around the stem of the plant.
When Is the Best Time to Put Mulch on a Garden?
Garden mulch can be applied at different times throughout the year.
Rather than waiting for one exact month, it's usually more important to prepare the area properly and make sure the garden needs mulch.
If the soil is extremely dry, water it first. Remove established weeds and then spread the mulch evenly.
For the complete process, see our step-by-step guide to spreading mulch.
Is Mulch Useful in Christchurch Gardens?
Christchurch gardens can experience dry conditions, summer heat, strong winds and winter frosts.
Mulch provides a layer over the soil surface, which is one reason it is commonly used in gardens and landscaping throughout Canterbury.
If you'd like more information specifically about the benefits rather than the practical mulch questions covered here, read Why Use Garden Mulch?.
What Does Aged Arborist Mulch Look Like?
Arborist mulch is supposed to look natural rather than perfectly uniform.
It normally contains a mixture of chip sizes, bark and finer organic material.
As the mulch ages, the material begins settling and breaking down, helping create the darker forest-floor style appearance that we aim for with our mulch.
Because it's produced from real tree material, there will naturally be some variation between loads.
Can Arborist Mulch Be Used on Pathways?
Yes.
Arborist wood chips can also be used on garden paths, around larger plantings and in other landscaped areas where a natural finish suits the property.
Keep in mind that organic material will eventually break down, so pathways may need topping up over time.
How Much Mulch Should I Order?
The easiest approach is to measure first rather than guess.
Our calculator lets you enter different garden shapes and depths and then recommends an appropriate load based on the result.
Use our mulch volume calculator before ordering.
We currently supply 2m³, 4m³, 6m³ and 8m³ loads.
Can I Get Garden Mulch Delivered in Christchurch?
Yes.
Canterbury Mulch Delivery supplies aged arborist mulch directly to properties throughout Christchurch and surrounding Canterbury areas.
If you're specifically looking for local delivery information, see our Christchurch garden mulch delivery page.
That page is specifically about Christchurch delivery rather than general information about mulch.
How Does Mulch Delivery Work?
We've kept the ordering process simple.
Choose the amount of mulch you need, enter your address for a delivery price and leave instructions explaining where you'd like the mulch tipped.
For delivery times, truck access, tipping requirements and the complete ordering process, read how our mulch delivery service works.
Our dedicated delivery guide covers these details in full, so we haven't repeated them here.
Where Can I Buy Aged Garden Mulch?
If you've worked out how much you need, you can view our available aged garden mulch loads.
We offer different load sizes for everything from smaller residential gardens through to larger sections and landscaping projects.
Need More Mulch Advice?
If you're still working out what you need, these guides cover the main topics in more detail:
- Why Use Garden Mulch? — the benefits of mulching.
- Fresh Mulch vs Aged Mulch — which type is right for your garden.
- How to Apply Mulch for the Best Results — how to prepare and spread mulch.
- Laying Mulch Around Trees — correct mulching around established trees.
- How Our Mulch Delivery Service Works — ordering, delivery and tipping information.
- Mulch Calculator — calculate how many cubic metres you need.
Or, if you're ready to order, view our garden mulch delivery options.
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