Key Takeaways
- Bark is one type of mulch, not an alternative to it. Mulch is any material spread over bare soil to hold moisture and starve weed seeds of light, and bark chippings are one of a dozen common mulching materials.
- A retail 80L bag labelled “mulch” usually holds composted bark or a fine bark-and-wood blend, chosen for what it gives the soil. A bag labelled “bark chippings” holds bark graded by piece size, chosen for appearance and staying power.
- Bark chippings and composted mulch both want 5 to 7.5cm to control annual weeds properly, and up to 10cm where holding summer moisture is the point, laid straight onto soil rather than over a membrane.
- The optimal depth for bark chippings and composted mulch is 7.5cm for proper weed control, which works out at 75 litres for every square metre, or roughly one square metre per 80-litre bag.
People ask me this expecting a clear winner. There isn’t one, because bark is a mulch: the choice is between two bags doing two different jobs. The bag marked mulch is usually the cheaper one, which is what makes people suspicious of it. It is cheaper because it is a different product, not a worse one.
Is Bark the Same as Mulch?
Bark is a mulch, but mulch is not bark: mulch is anything spread over bare soil to hold moisture and block light from weed seeds, and bark is one material that does it. Compost does the same job, and so do leaf mould, straw, wood chip and gravel. “Mulch” on a bag tells you what the contents are for and nothing about what they are. “Bark” tells you what is in it: pieces of tree bark, stripped at the mill and graded by size, with no heartwood. Wood chip is the wood itself through a chipper, with little or no bark.
So when someone asks me bark or mulch, I ask which bag they are holding. Nine times out of ten the “mulch” one is a composted bark, or a fine bark-and-wood blend, bagged for what it gives the soil. The chippings are sold for how they look and how long they hold up. Same family. Different jobs.
What Is the Difference Between Mulch and Bark?
Bark chippings stay on the surface and look the part for years; a composted mulch disappears into the soil and feeds it, and every other difference follows from that one.
| Feature | Bark chippings | Composted bark | Wood chip |
|---|---|---|---|
| What is in the bag | Graded pieces of bark, no heartwood | Bark rotted down until it looks like dark compost | Chipped wood, little or no bark |
| Lifespan before topping up | 2 to 3 years, 3 to 5 for chunky pine | A year or two | Colour goes in a season, the layer lasts longer |
| Weed control at 7.5cm | Good, against annuals only | Good, weaker as it rots in | Good, against annuals only |
| Feeds the soil | Slowly, over years | From the day it goes down | As it rots; pinches nitrogen first if fresh |
| Stays put in wind | Coarse grades stay, fine grades wander | Blows when dry | Chunky, stays put |
| Best used for | Borders on show, shrub and rose beds | Tired soil, heavy clay, roses | Paths, working areas, under trees |
Two things in that bark vs mulch table catch people out. The first is the bag. Anything sold as a bark and wood mix is usually heavy in shavings, which rot fastest, tie up the most nitrogen while they do it, and look tired within a season. You cannot judge that from a photo, so read the description, and where you are choosing between our own grades the decorative bark range puts them side by side.
The second is nitrogen. Bark and wood do take it as they rot, but a surface layer takes it from the top few millimetres, for a while, and an established shrub never notices – just don’t dig fresh bark or chip into the ground, as then it is a different matter.
Which Is Better, Mulch or Bark?
Bark chippings win on looks and lifespan, composted mulch wins on feeding, so your goal decides which is best for your needs. My short answers:
- Beds and borders on show: bark chippings at 5 to 7.5cm, laid on the soil, a coarse grade if the site is windy. The most popular border finish in Britain for a reason.
- Roses, hungry perennials and tired ground: composted bark, capped with chippings if weeds are the battle. This is the one for soil that needs building rather than decorating, and it is what I use where peat used to go.
- Slopes and exposed ground: chunky bark or wood chip, never a fine composted grade. Fine material dries, lightens and ends up on the lawn; bigger pieces sit into each other and stay.
- Mediterranean and dry-garden planting: neither. Stone keeps the collar of the plant dry where any organic mulch holds damp against it, and that is the honest reason to pick gravel there, not taste.
Whichever you pick, it goes on soil, not membrane, a hand’s width from every stem. The method, and why I never put fabric under bark, is in how to lay bark chippings.
Is Bark More Expensive Than Mulch?
Graded bark chippings cost more per litre than wood chip, and the chunkier the grade the more it costs, but they also last the longest, so per year on the ground the gap mostly closes. The mistake is pricing per bag. Price the job per square metre at the depth you are laying, because that is what you are buying.
At 7.5cm, the depth that actually holds weeds down, you need 75 litres for every square metre, which makes an 80-litre bag good for about one square metre of any of these materials. A 3 metre border a metre and a half deep is 4.5 square metres, so 340 litres, five bags with a little spare. Run yours through the bark and wood chip calculator, because a border nearly always swallows more than people budget for. Where money is tight, tree surgeons will often give chip away, and it makes a decent mulch once it has aged a few months, and leaf mould costs nothing but time and patience.
Next Steps
Pick the job first and the bag picks itself. For a border on show, start with the bark chippings buying guide or go straight to our bark and mulch range. For soil that needs feeding, composted bark fines are the product, the soil improver range holds the rest, and compost as mulch explains when compost does the job instead of bark. Not settled on bark at all? What is mulch covers every material in one place. We deliver in bags and bulk bags, and if you are torn, get in contact.
If you are still torn between mulch and bark and would rather talk it through with a person, ring Outdoor Aggregates on 0330 043 7585. The office is open 7am to 7pm, seven days a week.
Have you ever mulched a border with the cheaper bag to see if it mattered? Which did you use, and how long did it last? Let us know in the comments below.
FAQs
Which is better, mulch or bark chips?
Bark chips are the better buy for a border you want tidy for two or three years, and a composted mulch is the better buy where the soil needs feeding. One is a material and the other is a job, so they are not rivals.
Is bark mulch better than wood chips?
Bark mulch holds its colour and shape far longer than wood chip, so it is the one for beds on show; wood chip is cheaper, fades within a season, and earns its keep on paths and working areas.