Mulch is an essential element to keep your plants looking fantastic, but not every type delivers the same results.
A 3” to 4” layer of bark or wood chips is often used as a form of mulch on top of soil. The difference between wood chips, bark, and other types of mulch are their ability to insulate the ground, retain moisture in soil, deposit nutrients, prevent weed growth, and how often they need to be replaced.
While some of those abilities can be determined by their size, there are other factors to consider that may make or break your desired results.
So how can you choose the best mulch for your garden?
In this guide of the differences between mulch, bark, and wood chips I will explain why you should use mulch, what it’s made of, the pros and cons of each type, and answer frequently asked questions.
Once you know the basics, you’ll see that mulch beautifies your landscape while helping your garden flourish!
Why Use Mulch?
Mulch helps the plants and soil in your garden in many different ways.
A layer of mulch three to four inches deep deters weed growth. If weeds do pop up in the mulch, it’s easier to pull them from the loose material.
Mulch protects the soil around your plants. A mulch layer will keep the soil cooler in the summer and warmer in the winter, so plant roots have less chance of incurring damage as the weather changes.
Mulch also retains moisture, so the soil in your garden dries out slower. In my garden, I find I have to water non-mulched or thinly-mulched areas much more often than those with a deep layer.
To determine the moisture levels in your soil, check out our guide on the best soil moisture meters to buy.
The last reason you should use mulch is for the organic matter that forms as some types of mulch break down.
This natural material provides nutrients to the soil and helps the soil in your garden stay loose and aerated. Mulch is a great way to amend poor soil slowly.
What Is Mulch Made Of?
Mulch can be made of a variety of materials, some organic in nature and some not.
Next, are a list of common mulch materials with the pros and cons of each.
Shredded Bark or Wood
- Readily available
- Comes in several colors
- Retains moisture and controls soil temperature
- Needs replacement every year or two
- Color fades
- May blow or runoff during high winds or heavy rainstorms
- Can be made from recycled wood that contains potentially harmful chemicals
- Full of nutrients to feed plants
- Can make your own/cost-effective
- Retains moisture
- Breaks down quickly
- May grow mushrooms or plants from spores and seeds within the compost
- Easy to spread
- Lasts through many seasons
- Adds organic matter to the soil
- Can float away during heavy rains
- Has a more rustic appearance
- Inexpensive (or free if you have pine trees)
- Doesn’t wash or blow away easily
- Ideal for mulching rhododendron, azaleas, and other acidic soil-loving plants
- Adds acid to the soil, which could be harmful to many plants
- Needs replacement every year as the needles decompose
- Lasts many, many years
- Won’t blow away
- Color won’t fade
- Looks realistic
- Doesn’t provide nutrients or organic matter
- May smell for several months
- Won’t blow away
- Never needs replacement/won’t break down
- Easy to walk on
- Doesn’t break down into useful organic matter
- Weight can compact the underlying soil
- Hard to add new plants
Types Of Bark Mulch
Bark mulch is a popular choice for gardening experts who appreciate the ease of application, the longevity of the material, and the organic nature that adds nutrients and improves soil quality over time.
Bark mulches consist of chunky pieces that take longer to decompose. Bark’s purpose is to protect the tree, so using this sturdy material means spending less money refreshing your garden’s mulch layer.
Bark nugget mulches come in a variety of sizes, from mini to jumbo, so you can change up the appearance of your planter beds to suit your taste.
Nugget-style mulches come from the bark of pine or cedar trees.
Bark mulch is also available in a shredded style, like the bags of cypress bark mulch commonly sold at home improvement stores. Shredded-bark mulch is finer in texture, which means it will decompose and need replacement sooner.
Some mulch may have a “chunk” or “nugget” description on the label that could be large wood chips and not bark material.
Actual bark mulch will have the proper texture and will have the word on the label, whether its shredded or nugget style.
Frequently Asked Questions
What Is Black Mulch?
Black mulch is nothing other than standard wood mulch that gets its color from environmentally-safe carbon dye.
Frequently, manufacturers make colored mulch from recycled wood products that could harbor harmful chemicals if the wood was treated to prevent rot or pests.
Look for a certified CCA-free mulch logo to ensure safe handling and the health of your plants.
Black mulch can make your planter beds “pop” as the dark background will highlight your vibrant plant colors.
The downside is that the intense color fades quickly, and the dark tone absorbs more heat, which can damage delicate root systems.
Can I Use Pine Bark Nuggets?
You can use pine bark nuggets as mulch, but do be aware that when they begin to decompose they use up nitrogen in the soil and change pH levels, which can deter plant growth.
Pine bark nuggets are ideal for shrub planters since the root systems aren’t as liable to have issues from changes in soil pH composition. However, you must be extra careful when changing pH and making soil acidic for blueberries.
Pine nuggets are also better for mulching areas with a flat surface. Pine bark tends to float off during heavy rains, so filling a sloping planter with pine bark nuggets is not the best idea.
On the bright side, pine bark nuggets retain their natural pinky-grey-orange tones for several years, which means fewer top-offs. A quick raking will turn over the chunks and rejuvenate the color.
Can I Use Freshly Chipped Wood As Mulch?
What could be better than a free (or low-cost) pile of mulch? Whether you need to remove a tree on your property or have access to a municipal mulching center, you can use fresh-chipped wood as a mulch in most instances.
Avoid using chips from Walnut trees, as the chemicals in this species cause allelopathy, which can be harmful to nearby plantings.
Fresh wood chips usually combine all parts of the tree, which adds nutrients to the soil as it decomposes for better plant health.
- Spread six to eight inches of fresh wood chips around plants and shrubs, since the material settles and breaks down faster than other types of mulch.
- Refrain from pushing wood chip mulch up against tree trunks as it encourages moisture and fungal growth.
- Keep the mulch back a few inches so the tree trunk can breathe!
Is Wood Mulch Good For Gardens?
Using wood mulch in your vegetable garden can be good or bad, depending on who you ask.
Some gardeners only use wood mulch for pathways between plantings and choose more organic and nutrient-rich choices like grass clippings or compost as mulch around the plants.
Other gardeners love how wood mulch holds in moisture, slowly adds nutrients, and deters weed growth around their vegetable plants.
If you choose to use wood mulch, never mix it into the soil of a garden bed. The initial nitrogen depletion of decomposing wood could stunt the root development of vegetable plants.
Keep the mulch on the surface, and rake the wood mulch clear before tilling amendments into your garden bed.
What you choose is a personal preference, but I did find this interesting study that shows an increase in nitrogen levels (and crop yields) by using wood mulch over fifteen years on a farm in NY.
What Mulch Lasts The Longest?
Obviously, a mulch made from rocks or rubber will last the longest. But most people prefer to use organic material like shredded wood, bark, or wood chips that are affordable, eco-friendly, and visually appealing.
Of the three types of wood mulch, large bark nuggets will last the longest. Expect chunky nuggets to last three or four years before you need to replace them. Next up for longevity is smaller bark nugget mulch, which should last around two years.
Wood chips and shredded bark mulch typically need replacement or a top-off each year. Very fine wood shavings or shreds may only last six months before they break down too much to be useful as a mulch.
It’s clear to see using mulch provides an array of benefits. Protect your investment in your home’s garden or landscaping plants by using mulch to retain moisture, deter soil erosion, add nutrients, and reduce weeds.
A well-tended yard, with beautifully mulched planters, will increase your home’s curb appeal as well as keep your plants happy and healthy.
I hope this guide to the differences between mulch makes choosing the best type and size for your garden and landscaping much easier. Whether you decide on bark, wood chips, or another type of mulch material, you can be confident your plants will thank you!