Which mulch should I buy?
Four facts about the bed decide it, and none of them is the color. Does water run through it, does wind get at it, do you dig it or eat out of it, and do you want the soil underneath to improve? Everything else — the pros-and-cons lists, the ten paragraphs about cypress — is downstream of those.
| If this is your bed | Use | Avoid | Why |
|---|---|---|---|
| A slope, or a bed that washes out | Shredded hardwood, pine straw | Bark nuggets, rubber, straw | Shredded and needled mulches knit into a mat. Nuggets float and end up in the lawn. |
| Open and windy | Shredded hardwood, compost, stone | Straw, dry leaves | Light material walks. Straw is the worst offender until it mats down and stays. |
| Vegetable beds | Straw, shredded leaves, compost | Rubber, stone, dyed mulch | You want it gone by fall and turned in. Permanent mulches are a permanent mistake in a bed you dig. |
| Right against the house | Stone, or a bare 6–12 in strip | Any deep organic mulch on the siding | Not termites — moisture against the wall, and an inspection strip you can see. |
| Under a light-colored wall or car | Large bark nuggets, cedar | Aged shredded hardwood | Artillery fungus. See below — this is the one that ruins siding. |
| Playground fall zone | Certified rubber or engineered wood fiber | Stone, bark nuggets | Fall attenuation is a tested spec, not a preference. |
| Around blueberries, azaleas, rhododendrons | Pine straw, pine bark | — | Mildly acidifying as it breaks down, and it looks right. |
| You want the soil to get better | Arborist chips, leaves, compost | Rubber, stone | Only the ones that rot feed anything. That is the whole trade. |
Where two rows disagree — a windy slope you also grow tomatoes in — the vegetable row wins; you can re-mulch a bed that blew out, but you can't get rubber crumb back out of soil.
How long does each mulch last, and what does that cost?
This is where the published advice quietly gives up. Every mulch guide tells you bark lasts two or three years and rubber lasts ten or twenty; most of them also print a price per cubic yard. Almost none of them divide one by the other, which is the comparison anyone standing in the aisle is actually making. Price per 100 square feet, divided by the years it stays put — laid at the depth each material is actually used at:
| Mulch | Depth | Lasts | Typical price | Per 100 sq ft to lay | Per 100 sq ft / year | Feeds soil |
|---|---|---|---|---|---|---|
| Shredded leaves | 3 in | 1 yr | free | — | $0 | yes |
| Decorative stone or river rock | 2.5 in | 25–50 yr | $80–150 / yd | $62–116 | $1–5 | no |
| Arborist wood chips | 4 in | 3–5 yr | $0–25 / yd | $0–31 | $0–10 | yes |
| Rubber mulch | 1.5 in | 10–20 yr | $8–10 / 0.8 cu ft bag | $125–156 | $6–16 | no |
| Pine straw | 3 in | 1–2 yr | $6–9 / bale | $12–18 | $6–18 | yes |
| Pine bark nuggets | 3 in | 3–5 yr | $40–60 / yd | $37–56 | $7–19 | yes |
| Cedar or cypress | 3 in | 3–5 yr | $45–70 / yd | $42–65 | $8–22 | yes |
| Shredded hardwood bark | 3 in | 2–3 yr | $30–50 / yd | $28–46 | $9–23 | yes |
| Compost as mulch | 1.5 in | 1 yr | $35–60 / yd | $16–28 | $16–28 | yes |
| Straw (wheat or oat) | 4 in | 0.5–1 yr | $8–12 / bale | $11–17 | $11–34 | yes |
Sorted by annual cost. Coverage computed from each mulch's own depth by the mulch calculator's engine; lifespans from extension and industry guidance; prices are typical 2026 US bulk and bagged figures and are the softest number here — put your own supplier's quote in and the order barely moves, because lifespan drives it. The annual range is the cheapest price lasting longest against the dearest lasting least.
Stone costs about 2.4× what hardwood does to lay — $62–116 per 100 sq ft against $28–46 — and about a fifth as much per year, because it never leaves. Rubber lands between them at $6–16 a year. Hardwood, the default, is mid-pack at $9–23. If cost per year were the only question, you'd gravel the whole yard.
It isn't, and the table says why in its last column. The mulches that win on price are the ones that never become soil: no organic matter, no worm activity, no improving clay. You are not buying mulch, you are buying mulch plus soil improvement, and the moment you stop valuing the second half, stone wins by a mile. Decide which purchase you're making before you compare prices.
What a 400 sq ft bed costs over ten years
The per-year number hides the shape of the spending: organic mulch is small and repeated, permanent mulch is one large hit. Same bed, same decade:
| Mulch | Laid once | Times in 10 years | 10-year total |
|---|---|---|---|
| Arborist wood chips | $62 | 3 | $185 |
| Decorative stone or river rock | $355 | 1 | $355 |
| Pine straw | $60 | 7 | $420 |
| Pine bark nuggets | $185 | 3 | $556 |
| Rubber mulch | $563 | 1 | $563 |
| Shredded hardwood bark | $148 | 4 | $593 |
| Cedar or cypress | $213 | 3 | $639 |
| Compost as mulch | $88 | 10 | $880 |
400 sq ft — a generous foundation border — at each mulch's own depth and midpoint price. Applications are rounded up: you can't lay four-fifths of a mulching.
Read the rubber row against the hardwood one. Rubber costs $563 on day one against $148 for hardwood, and breaks even at year 8.7 — just short of the 10 years that is the bottom of its own claimed life. A product that only starts paying for itself around the age it might need replacing isn't a saving; it's a bet on the top half of the manufacturer's number. Stone is the one that genuinely runs away with it: $355 once against $593 of hardwood over the same decade, and it'll still be there in 2050.
Does wood mulch steal nitrogen from my plants?
The nitrogen-tie-up story is true chemistry applied to the wrong picture. Decomposing wood does pull nitrogen from its surroundings — when it's mixed into soil, which is why you don't till fresh chips into a bed. Laid on top, the effect is confined to a thin boundary layer at the mulch–soil interface, millimeters deep, well above where roots feed. Washington State's review of the arborist-chip literature is blunt about it: surface-applied wood chips don't reduce soil nitrogen, and over years they raise nutrient levels. The nitrogen-poor boundary is doing something useful, too — it's part of why a mulched bed grows so few weed seedlings.
The practical version: never dig fresh wood into planting soil, don't dump 4 inches of chips over a tray of just-sown seed, and otherwise stop worrying. If a bed of shrubs under chips looks pale, the answer is usually the same as everywhere else — feed it — and the fertilizer calculator will tell you how much.
Does mulch attract termites?
Not the way the warning implies. When researchers offered subterranean termites a choice of landscape mulches, the wood chips were near the bottom of the menu — they prefer softer, higher-nutrient material, and some woods actively repel them; cedar's thujone is the standard example. Mulch doesn't summon termites into a yard that didn't have them.
What mulch does do is hold moisture, and moisture against siding is a real problem — for the wood, for the paint, and for whoever has to inspect the foundation. That's why the advice survives even though the reason given for it is wrong: keep any mulch a hand's width off the siding, and leave a visible inspection strip. Stone or bare soil in that first 6–12 inches, mulch beyond it.
Black specks all over my siding: artillery fungus
This is the mulch problem nobody warns you about until it's happened, and it's genuinely the deciding factor for beds against a light-colored wall or beside where you park. Sphaerobolus — artillery fungus — lives in decaying wood mulch, and it fires spore packets several feet toward the brightest surface it can find. They dry onto vinyl, paint and car finish like specks of tar and are close to impossible to remove without taking the finish with them.
Penn State ran 27 mulches to see which resisted it. The finding that matters: large pine bark nuggets were the most resistant — they stay hard and dry, which the fungus dislikes — with cypress next. Aged shredded hardwood, the standard landscape mulch, was among the worst. No natural mulch resisted forever; given enough time all 27 supported it. Blending mushroom compost in at 40% or more suppressed sporulation dramatically, which is the fix if you're committed to shredded mulch. And since it's the old mulch that harbors it, refreshing rather than endlessly topping up helps.
If you have white siding and a north-facing bed, this outranks every other consideration on the page. Use nuggets, use stone, or move the bed away from the wall.
Is dyed mulch safe?
The dye is the least of it. Colorants on commercial mulch are iron oxide (the reds and browns) or carbon black — the same pigments used in concrete, and not a plant or pet concern at these rates. The real question is what got dyed: dyed products are usually made from recycled wood waste, and the cheapest end of that stream has historically included pallets and construction scrap, which can include CCA-treated lumber. Reputable suppliers use clean recycled wood and will say so.
Two practical notes regardless of source: dyed mulch is shredded wood with no bark, so it breaks down fast and greys within a season, and it is not a defense against artillery fungus — coloring only delays it. If you want color that lasts, that's an argument for cedar or stone, not for dye.
Free wood chips are the best deal in landscaping
Tree crews pay to dump chips. Sign up with a local arborist or a chip-matching service and they'll bring you a truckload for nothing — which the table above prices at $0 to $10 per 100 sq ft a year, against $9–23 for the bagged hardwood doing the same job less well. Chips are coarser, so they last 3–5 years, suppress weeds better at 4 inches, and are the single mulch soil scientists recommend most consistently for trees and shrubs.
The honest catches: you get a whole truckload whether you wanted one or not, it lands in the driveway, it's a mixed species and appearance, and it's too coarse to look right in a formal front bed. For a back yard, an orchard, paths or a shrub border, none of that matters. Shredded leaves are the other free option and the best mulch there is for vegetable beds — run the mower over a pile and spread them.
How deep, and how much?
Depth is per-material and the numbers are in the table above: 3 inches for shredded bark, 4 for coarse chips, 1.5 for compost, and thin for anything that mats. Deeper is not better — past about 4 inches you start excluding air and water rather than conserving them, and mulch piled against a trunk kills the tree slowly enough that nobody connects the two.
For the arithmetic — cubic yards, how many bags that is, and whether bulk delivery beats bagged for your quantity — the mulch calculator does it from your bed dimensions. For stone, order by the ton rather than the yard and use the gravel calculator; a yard of river rock weighs well over a ton and the pricing follows the weight.
Sources: Chalker-Scott, Using Arborist Wood Chips as a Landscape Mulch, WSU Extension FS160E, and the WSU wood-chip literature review (nitrogen, weed suppression, soil effects); Penn State Extension, Artillery Fungus in Mulch, and Davis et al.'s 27-mulch sporulation trial and mushroom-compost work; Duryea et al., Will subterranean termites consume landscape mulches? and Long et al. on mulch and termite foraging; Clemson HGIC 1604 and NC State Extension mulch guidance (materials, depths); typical 2026 US bulk and bagged prices from retail and bulk-yard listings, stated as typical.