What is Cedar Mulch and What is it Used For?


Ask most gardeners what the best garden and landscape mulch is, and a good percentage of them will answer cedar mulch. It’s attractive, great for moisture retention, it repels termites, controls weeds, and smells pretty amazing to boot. But does it really live up to its hype, or is it just another case of style over substance? Here’s what you need to know that you might be ready to ask your landscaper.

What Is Cedar Mulch?

As Seeds and Spades explains, cedar is a conifer tree species that’s found throughout many parts of the world. Known for its durability, attractive color, and distinctive aroma, its wood has become a popular material in shingles, fencing, furniture, decorative handicrafts, and more besides. When the bark of the cedar tree is stripped then either chipped or shredded, it forms a mulch that can be used in gardening and landscaping.

What are the Properties of Cedar Mulch?

What makes cedar mulch different from other kinds of mulch? Its chemical composition. Cedar boasts two incredible chemicals, namely:


Ever taken a whiff of cedar and wondered what makes it smell so good? The answer is Thujaplicin, a chemical compound that not only smells great, but which boasts anti-fungal, antibacterial, and antioxidant qualities too. If you can find it, stump up for red cedar mulch – it’s usually a little more expensive, but thanks to its extra high levels of Thujaplicin, it smells even better than the usual kind.

Plicatic Acid

When it comes to stopping rot from setting in, Plicatic acid is a powerhouse, boasting even stronger defenses against decay than Thujaplicin. On the downside, it’s also known as an allergen, so beware of using cedar mulch if you have allergies.

What are the Benefits of Cedar Mulch?

So, we know what cedar mulch is. But why exactly should you be spreading it over your garden?

Moisture Retention

The primary reason gardeners use cedar mulch is for its moisture-retaining properties. Cedar acts as a barrier between the soil and the elements, resulting in less evaporation, improved soil temperature regulation, and protection from topsoil moisture loss, all of which stops your soil from drying out and helps your plants thrive. Watering needs are reduced, maintenance is reduced, and your garden will start regulating itself with far less effort required on your part.

Weed Control

As traditionalgardening.com notes, cedar mulch is great at protecting your garden from pesky weeds. By covering the soil, it stops weeds from reaching the surface and blocks the sunlight needed for germination. Without having to compete for essential nutrients with invasive weeds, your plants will thrive.

Insect Repellent

If there’s one thing insects hate, it’s cedar mulch. Cedar produces natural oils with a strong scent – most people love that scent, but it turns the stomachs of pests. If you have a particular plant or tree that insects love to feast on, a little bit of cedar mulch around its base should be enough to deter them.

Soil Insulation

If you live in a climate that experiences extreme temperature fluctuations, cedar mulch could make all the difference to the health of your garden. It acts as a form of insulation, keeping it cool in summer and warm in winter, creating the kind of stable, all-year-round environment that plants love.


This next benefit won’t necessarily make your plants thrive, but it will make them look a lot more attractive. If you like a neat, uniform look to your garden, a layer of cedar mulch can help you achieve it. Cedar’s tan, orange or red hue looks wonderful against foliage, helping to give your garden a big boost in the beauty department. if that wasn’t enough, it smells good too.


If you’re sick of how quickly most wood mulches break down, you’re going to love cedar mulch. Unlike pine, hardwood, and cypress mulch that start to lose their color and shape quickly and need to be replaced every couple of years, cedar mulch keeps in good shape for much longer. It’s a bit more expensive than other options, but the cost-savings of not having to replace it so often give it the advantage.

What are the Disadvantages of Cedar Mulch?

Cedar mulch, as we’ve already seen, comes with some great benefits. That’s not to say it’s a magic bullet though. For all its pros, there are also several cons you need to be aware of. These include:

Nitrogen Depletion

As Trees.com explains, when cedar mulch starts to decompose, it can draw nitrogen from the soil. If the mulch is only in contact with the top level of soil, this won’t be a problem, as plants will still be able to draw nitrogen from further down in the soil where their roots are. However, if the mulch has been mixed with lower layers of soil, it can have a detrimental effect on plant growth.

Soil Imbalance

When fresh cedar is applied, it can leech very small amounts of acid into the soil. If your soil is slightly alkaline, it probably won’t have any noticeable impact, and could even help improve the general pH balance. If, however, your soil is already acidic, the cedar could make it even more so.

Potential Allergen

Cedar has a very distinctive smell. Most people find it appealing, but if you or any member of your family has allergies, you might find it’s best avoided. Although it’s rare, people with particularly sensitive reactions to smells may find the strong aroma triggers sneezing, coughing, watery eyes, and even skin irritations.

Bug Killer

Cedar mulch is a great way to keep bugs and creepy crawlies from attacking your plants. The only problem is, not all bugs are harmful to plants. Some are downright beneficial. Insects like ladybirds, hoverflies, butterflies, bees, and wasps are all good to have around, either because they keep less desirable garden pests like aphids under control, or because they help the pollination process. Unfortunately, cedar isn’t discriminating. and is just as likely to repel the good guys as the baddies.

How to Use Cedar Mulch

Cedar mulch is easy to apply. Simply spread an even level measuring around 3 inches thick over the top layer of soil. If you’re using it around trees and large shrubs, cedar chippings, which are the heavier of the two varieties, are best. If you’re using it around bedding plants and flowers, opt for the more delicate shredded cedar instead. Be sure to leave a small gap between the mulch and the base of trees and shrubs: if you take it too close, you can limit airflow and encourage root and disease to set in.

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