Wooden chip mulch: the whole lot you must know

One of the things that landscapers and gardening professionals keep touting is mulch. There are many different types of mulch, such as leaves, clippings, or straw mulch such as garden straw. However, a widely used and sometimes controversial material is wood chip mulch.

Adding mulch along with compost is great for your plants. Still, there is debate about which organic matter is best for the soil. The use of wood chip mulch creates rich soil as the Back to Eden method proudly advertises. However, using wood mulch may not be ideal in every situation!

In this article, we're going to break down the benefits of wood chip mulch for gardeners. With the right information and action, you can incorporate this incredibly useful material into your landscape and help your garden grow.

What is wood chip mulch?

Wood chip mulch can be beneficial if used correctly. Source: rick__wilson

This is a big question that we're breaking down for you here. It is important to know which mulch is available for you and to apply the appropriate materials to provide the right nutrients for your garden of choice.

Arborist Chip Mulch

This material is a source of chips that are from the by-product of your local tree care or the work of arborists. It can include any part of a tree that has been removed by an arborist or service: berries, branches, leaves, flowers, and even roots.

This is natural, organic material that has been passed through a wood chopper. Usually it is the remains of arborists that have been broken down into arborist wood chips. Sometimes it's old trees, sometimes fresh wood.

It is also common to find arborist chip mulch in areas where orchards are predominant.

Wood shavings in sacks

You can usually find this at your local hardware store or plant nursery. It is mulched tree material in 2 to 3 inch pieces. It can be natural and organic material, tree material straight from a lumber yard or tree service, or it can be wood that has been extensively chopped.

Most wood chips come from trees that have been used in industry, not fresh and freshly harvested wood. But when you receive these you will also receive plastic bags to send to the nearest landfill.

Modified wood chips

These can be sacked wood chips that have been treated to reduce their flammability. They can be treated with pesticides and herbicides that prevent weeds and insects from taking over your garden.

This material is often used in situations where a homeowners association has determined a preferred mulch color. Sometimes they are reflective or colored in a specific color. They can contain both chemicals and organic substances.

Think of wood chips that have been put in some form of additives to prevent disease, weeds, fire, or to stain them. It is still packed in sacks, which means more plastic for the landfill.

Bark mulch

Bark mulch is crushed tree bark that comes from different sources. Most come directly from trees and people who work with trees. Other sources include sawmills and furniture manufacturers to name a few. It is an absorbent mulch that comes in flakes. It can often be full of splinters and easily matted, but the fine particles look great in a garden.

Crushed wood mulch

This is the stuff you'll see in neighborhood gardens. Crushed wood mulch can be colored, but is usually finely crushed material like pine shavings. Generally speaking, this is a finer mulch, around 1 inch or smaller, which makes it very visually appealing.

It is generally a by-product of wood and papermaking and is widely used to maintain aesthetic uniformity by retaining moisture and blocking weeds. It has one drawback, however; it can sometimes be fine enough to get together and can slow drainage slightly.

Advantages and disadvantages of wood chip mulch

Colored chip mulchWood chips can be stained with either natural or chemical dyes for color fastness. Source: Jasonprine

Let's discuss the benefits and pitfalls associated with each as a source of mulch or compost. So you have taken these into account before using wood chip mulch at home.


In general, when used properly, wood chip mulch can be an excellent source of nutrients for your soil or compost heap. Wood chips also keep water in the soil, reduce weeds and counteract erosion of the topsoil.

Ask any nut in regenerative agriculture and they will tell you that wood chips simulate the same process that takes place on the forest floor, one of the richest environments around.

Wood chip mulch is a great way to prevent sludge build-up in your garden due to its water-retaining properties. It looks great in any landscape, especially if you managed to match the colors. Some wood shavings, like wood shavings from arborists, may even be free.

Adding a layer of wood chips to the ground to cover the surface of the ground, reduce grass growth around trees, or fill in a muddy patch is a great way to do the mulching naturally. Some modified wood shavings keep pests out of the garden and allow for regular healthy growth. Shrubs surrounded by a layer of red material can do a pretty good job of leveling out grass.

Another good use for wood chip mulch is as a temperature controller. During the winter months, mulch plants often have warmer root systems, making them much easier to withstand colder conditions. A thick layer of wood shavings applied in the fall can be the factor protecting your plants from severe weather damage.

Some types of mulch, such as aromatic cedar, can reduce pest populations. The aromatic nature of the wood acts as an effective deterrent.

If you've ever sprinkled wood mulch, you know this is a great way to add a touch of pizazz to your landscape that will last for more than just one season. And when it collapses, build rich soil!


Pile of wood chipsDeciduous mulch may only be available in large quantities. Source: Oregon State University

When processing wood mulch, however, there are a few points to consider.

For one thing, many fear that these chips could pull nitrogen out of the ground. They reduce the nitrogen content in the top inches of the soil, but further down the soil's fertility remains unaffected. This makes them a great choice for weed reduction, but not great if you're starting out with seeds! Don't mix mulch into the soil as this will bring the decomposing material closer to your plant roots.

They can suffocate plants and trees if not used properly. The term "volcanic mulch" is often used for trees that have a mulch mound directly on the trunk. This type of mulching of trees and other plants is dangerous as it can damage the stem or base of the plant.

Compost and wood mulch together can make water retention too high for some plants and trees. As a result, they could get root rot. Usually this is less of a problem with larger wood chips, but it can be a problem with fine materials like shredded bark or shredded wood chips.

Although colored wood chips last more than a season, they will fade over time. For those looking for a consistent color, top dressing regularly to get the right shade.

Mulches are not a comfortable surface for walking barefoot. Covering the surface of the ground with sharp material such as wood chips or crushed bark mulch may not be preferable to homeowners for this reason.

Termites may find fresh wood chips and want to get to your home from that pile. Although they are not technically "attracted" to tree mulch, they may find the layer of mulch a good temporary place to stay and then move into the wood in your home once the mulch pile is reduced. For this reason, it is best to keep wood mulch at least three feet away from your home. For many people, this isn't an option as garden beds are placed right near foundations, so be sure to keep an eye on it!

Mulch breaks down quickly and needs to be topped up regularly. It takes a lot of energy to do this. Even if you plan on hiring a mulching service for you, it can get costly. Packaged wood chips, modified wood chips and tree bark need another layer at least every few years as they become a mixture of decomposed waste from fresh materials. As they compost, they will improve the soil, but you still need to make sure that you top up it regularly.

Treated or modified mulch may not be the best option for your garden, especially when growing vegetables. For example, a modified mulch that contains Preen or another herbicide may reduce the germination rate near the mulched area, and therefore you may not be able to start seeds at this point.

There is concern that disease can be transmitted through certain types of tree mulch. While good fungi can live in your mulch, disease-causing fungi can too. This is especially a problem with arboriculture mulching, so it is best to request mulch from disease-free trees for the safety of your garden.

After all, tree care mulches may only be available in large quantities. Many arboriculture services simply want to drop off a truckload of 10 to 20 cubic feet at a time, and if you are in a suburb you may find it difficult to handle that type of crowd.

So, think about what you need mulch for and how you will get the mulch before you make a big purchase.

Where to use wood chips

Redwood bark mulchRedwood bark mulch is finely shredded, but is often full of splinters. Source: Lorin Nielsen

Yes, wood mulch on the ground surface is a great way to mimic the soil of a rich forest floor. But there are right and wrong times to spread mulch. There are certain ways to layer them with compost and proper methods for spreading mulch around plants, trees, and shrubs.

Right timing

Mulch isn't something you want to plant directly into. You should wait until you even spread it on soil that you recently planted seeds in. Wait for your plants to grow before adding mulch for ground cover. This keeps the developing roots open for nutrient absorption. This also applies to transplants. Make sure the roots are clearly developed before adding fresh mulch to the soil.

Right distance

One very important thing to add when adding mulch to the soil in a vegetable patch or place where trees, plants, and shrubs live is to avoid mulching directly on the trunk or trunk. Leave some space between the plant, tree or shrub and the mulch. This not only allows trees, plants and bushes to breathe, but also gives them a small moat where moisture can collect and slowly and gradually utilize it.

The reason mulch gets the reputation for nitrogen stealing has to do with improper applications like volcanic mulching. Even if the mulch is organic and comes from a tree service that chops a healthy tree, too dense or too much mulch is a recipe for disaster. Improper mulching can kill a plant.

Mulching should not be applied to the ground where plants grow in a layer more than 10 cm deep. 2 inches is the minimum depth. Less than 2 inches and weed suppression is not possible. If you are spreading mulch on the ground to suppress weed growth, keep this in mind!

In areas where you want to prevent plant growth, a layer of 6 inch deep mulch is perfect. This prevents weeds from developing and reduces the frequency of backfilling the mulch layer. For example, 6 inches is ideal for paths.

Proper procurement

Make sure you have found a good source of mulch. If you're looking to grow vegetables, green mulch or some hardwoods like walnut may not be the best option for your situation.

Most vegetable gardeners prefer softwoods like pine that break down easily so they don't have to worry about improper plant growth.

Hardwood applied in the wrong situation can kill a plant. Some, like the black walnut, are allelopathic and can actually reduce plant growth where they're placed. It may take a while as the black walnut decomposes and the allelopathic states subside. When planning, consider the tree species of the mulch.

If your mulch is a purely aesthetic choice, you may not need to worry too much about the source. However, to make your organic horticulture easier, you should ensure that the supplier you are purchasing from does not contain any material that contains fungal pathogens or diseases.

It's horrible to have to come back from a free wood chip (that's great!) That is full of disease and is depriving the vegetables of nitrogen. It took me years, personally, to come back from it in one of my vegetable patches.

Good sources of mulch are often local tree care providers or websites like ChipDrop. However, you can get it at your local garden center, either in bags or in bulk. Typically, material from a garden center has been steam sterilized, giving it additional protection against the transmission of pests or diseases.

Building floor

You might prefer to use a mulch to build up soil. In this case, it can contain green matter and it can be hardwood. You can put it between the beds to decompose over time, or you can use it as a pathway. Green wood is great for this purpose as it is still fresh from chopping and may actually contain some green leaves to provide nitrogen. This also reduces the nitrogen loss during degradation!

frequently asked Questions

Wood rasping mulchWood chips can be an effective source of mulch. Source: arpent nourricier

Q: What is the best wood chip mulch?

A: It depends! Each wood chip mulch has a different purpose and each has its own suitable uses. Organic options like arborist chips are often considered to be the safest for the surrounding ecosystem.

Q: Does wood chip mulch attract termites?

A: Technically, no. But mulch too close to your home can cause termites to invade the structure of your foundation. Keep wood chip mulch at least 2 feet from your home to prevent this from happening.

Q: Are wood chips good for a garden?

A: If used correctly, yes! They are an excellent source of slowly decaying nutrients that will replenish your soil.

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