Cedar Mulch Pros and Cons: Should It Go In Your Garden?
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Cedar mulch has a bit of a reputation as being one the best garden and landscape mulches out there.
But does it live up to the hype?
Cedar mulch comes from the bark or inner wood (heartwood) of various species of cedar trees. It contains powerful resins and phenols that deter insects, have an aromatic smell and resist decay. But these qualities can be either pros or cons depending on the situation.
In this article, we’ll look at cedar trees and the unique properties they have to offer. We’ll also cover cedar mulch pros and cons in various applications.
Finally, we’ll give you some tips on how to make sure the cedar mulch you purchase is the real thing.
Let’s jump in!
RELATED: Cedar isn’t your only mulch option! For an in-depth overview of different mulch types and their uses, check out our detailed guide on mulching options.
What Is Cedar Mulch?
Cedar is a conifer, or evergreen, tree species that is native to many parts of the world.
Prized for its durability, scent and color, cedar is a popular material for shingles, fencing, decorative projects and many other uses.
Cedar mulch is made from the bark of cedar trees, and it’s available in chipped or shredded form. Chips tend to be heavier and form a denser mulch layer. Shredded cedar is much lighter and provides better airflow.
Properties Of Cedar
What is the primary factor that makes cedar wood so unique? The answer lies in cedar’s specialized chemical composition.
This chemical element is a true powerhouse that provides numerous benefits.
Besides protecting the wood from decay, thujaplicin also gives cedar its distinctive scent.
Among all the members of the cedar family, the western red variety typically has the highest thujaplicin concentration.
If it’s available in your area, springing for western red cedar mulch, also known as red cedar mulch, is probably a good idea.
Plicatic acid is another protective element that slows the decay process.
Thujaplicin usually gets the credit as cedar’s main defense against decay, but studies show that plicatic acid appears to be more powerful.
Unfortunately, plicatic acid is also responsible for cedar’s tendency to irritate allergies in some people.
My husband experienced this firsthand a couple of years ago when he built a raised garden bed out of cedar. He’s already prone to allergies, and he was sneezing and wiping his watering eyes for the rest of the day.
On the other hand, I rarely have any issues with allergies, and the cedar shavings didn’t bother me at all.
Benefits Of Cedar Mulch
So cedar contains some pretty impressive chemical compounds, but do they make a difference in your garden?
Yes! Let’s look at the benefits cedar has to offer.
Excellent Weed Prevention
All mulch materials inhibit weed growth by keeping seeds out of the soil and preventing sunlight from reaching seeds that are already there. Cedar is no exception.
However, certain chemical properties in cedar discourage plant germination and growth, providing an extra defense against weeds. Especially if combined with strategies to stop weeds from growing in mulch, you could be looking at minimal upkeep.
Most insects don’t like cedar’s strong scent and chemical composition. As a result, you should notice fewer bugs in your garden beds in cedar-mulched beds.
If you have a tree or plant that seems to be an insect magnet, using cedar mulch around the plant’s perimeter may help.
Most wood mulch, like pine, hardwood or cypress, tends to break down quickly and need replacement within a few years. In the meantime, these materials often take on a grayish color as they weather.
Thanks to its unique chemical elements, cedar mulch retains its color and shape for a long time. Even though you might spend a little extra at the outset, cedar can end up saving you time and money over the years.
Pleasant Natural Scent
If you’ve ever opened a cedar chest or closet lined with cedar walls, you’ve likely experienced cedar’s distinctive aroma.
It’s a fragrance that I personally really like. And if you do, too, using cedar as mulch lets you enjoy this pleasant scent outdoors.
Depending on the type of cedar trees used, cedar mulch can have a range of shades from tan to soft red.
Cedar is a great way to add color to your landscape without the use of chemical dyes.
Great for Termite-Prone Areas
If you love the look of wood mulch but live in a region plagued by termites, cedar could be a good solution.
The oils and resins in cedar are unappetizing to termites. As a result, spreading cedar near your home may help direct termites elsewhere.
Drawbacks Of Cedar Mulch
It’s not hard to see why cedar has a reputation for being an excellent mulch material for gardens and landscapes.
However, using cedar mulch may not be the perfect solution all the time. Here are a few potential drawbacks to keep in mind while you decide which mulch is right for you.
May Repel Helpful Insects
With its natural bug-repelling chemicals, cedar is awesome for deterring garden pests.
But one drawback to this quality is that helpful insects may also be less likely to find their way into your garden.
When I was choosing a mulch for my front perennial flower planting, this is something I was concerned about. I definitely didn’t want to drive pollinators, namely bees and butterflies, away when their numbers are already in danger.
One place I looked for information was beekeeping forums. I found that several beekeepers said their bees happily lived in untreated cedar hives, and that having cedar mulch or shavings around the hives didn’t seem to affect the bees’ activity in the least.
So I decided to use cedar in the bed. My spirea bushes were just starting to bloom when I spread the mulch (you can see one of them in the upper right corner of the photo below).
I noticed just as many bumblebees busily going over the blooms before, during and after laying the cedar mulch.
Now, that’s just my own personal experience, and I can’t speak to the possible effect on ladybugs, praying mantises or other garden friends. I actually don’t have many of those insects to begin with, so I can’t compare pre/post numbers.
If you’re actively trying to increase your population of beneficial insects, you may want to choose a different mulch material just to be on the safe side.
Aroma May Be Too Strong for Some People
The aromatic resins in cedar mulch are a big draw for many people. But those who have heightened sensitivities to smell or allergies may feel differently.
In fact, my kids were playing in the lawn when I was spreading the mulch. My daughter said, “What’s that smell?” When I replied, “Cedar. Doesn’t it smell wonderful?” she answered, “No, it smells terrible.”
So there’s obviously differing opinions here.
(I’ll also add that the “terrible smell” didn’t seem to interfere with her playing at all.)
If you’re concerned that the scent could be problematic for a family member or friend, take these precautionary steps:
- Don’t use cedar near doorways or windows where the scent could make its way into the house.
- Avoid applying cedar mulch to high-traffic, entertaining or play areas.
Expect to pay a little more when it comes to cedar vs cypress mulch. Other materials, like hardwood and red or black mulch, also typically carry a lower price tag than cedar.
The good news is that you may not notice much of a price jump if you’re working with a small area. Per bag, cedar usually a costs just a few dollars more.
On the other hand, you may be looking at a significantly higher cost if you have a large area to cover.
Can Be Allergenic
As we mentioned earlier, cedar’s high concentration of plicatic acid can be an allergy trigger for some people.
Where Can You Use Cedar Mulch?
Remember when we mentioned earlier that cedar can deter weeds by interfering with seed germination and early seedling development?
Some of cedar’s chemical compounds inhibit the growth of plants with shallow root systems. This quality is the main reason why cedar is such an effective weed deterrent.
That’s all well and good when it comes to weeds, but not when you’re growing vegetables. The negative effects seem to be especially strong when the mulch makes direct contact with the young plants.
There’s also another reason for concern in using cedar as mulch for vegetable gardens.
Most of the time, mulch sits on the soil surface, and the weed-fighting chemicals don’t penetrate deeply into the ground. However, in garden beds that you till frequently, like those for vegetable or annual flowers, old mulch gets worked into the soil.
The chemicals then make their way into the soil, and your vegetables and flowers may suffer. In these instances, you’re better off using materials like compost mulch, chopped leaves or grass clippings.
However, cedar is perfect for spreading around established trees and perennial beds.
And perennial vegetables, like asparagus and rhubarb, often have deep root systems, so feel free to mulch these beds with cedar.
How Much Cedar Mulch Do You Need?
If you’ve ever unsuccessfully guesstimated how much mulch you need, you know it’s a pain.
Instead, use this calculator to get the amount you actually need on the first try.
NOTE: Most people lay down a layer of mulch that’s between 2 and 4 inches deep.
Beware Of Cedar Mulch Imposters!
Unfortunately, not all mulch that bills itself as cedar heartwood or cedar bark mulch is actually made from pure cedar wood.
If you’re buying bags of mulch at a big-box store, look carefully at the ingredient label. Some of the products that appear to be cedar mulch may be a “cedar mulch blend.” These products may contain fillers such as:
- A mixture of other wood
- Recycled wood pallets
- Lumber byproducts
To avoid these sneaky imposters, look for mulch labeled “100% cedar” or “virgin wood.”
Fortunately, you shouldn’t run into this problem at all when bulk-buying mulch from a nursery.
Frequently Asked Questions about Cedar Mulch
So, is cedar mulch good? That depend on what you want to use it for.
Cedar’s unique properties make it a great choice for:
- Enhancing your landscape with long-lasting, colorful beauty
- Preventing weed growth
- Repelling insects
- Adding a pleasant aromatic element to your garden
As long as you’re aware of the potential drawbacks and appropriate usage, cedar mulch is an excellent choice that can yield benefits for many years to come.
Great article! Found out earlier in the year that our 2 kids are allergic to cedar mulch. Didn’t realize it was because of the plicatic acid though. Very helpful.