Mulch vs Compost vs Fertilizer (When to Use What)


With endless factors to consider the right choice between mulch, compost, and fertilizer can be confusing with minimal first-hand experience. The best choice is a matter of circumstance, timing, and goals.

Mulch, compost, and fertilizer are products that fuel the growth of plants. We have used all forms of these and learned which is more or less beneficial for particular circumstances and goals.

After this post, you’ll know which medium to apply for your situation and gain helpful inspiration.

MulchCompostFertilizer
(Mulch vs)Types: sheet mulch, shredded mulchMulch is fresh carbon-rich plant material that lays on top to protect life-rich soil or compost. Mulch is an organic solid that breaks down over a long period of time. After at least a year of robbing nutrients to break down, they offer a very slow, steady, and long-term release of micro and macronutrients.
(Compost vs)Compost is a well-broken-down organic matter that is ready to give nutrients. It is applied on top of a soil surface, can optionally be worked into the top inch of soil, and in desired cases, it can lay beneath mulch.Types: plant-based, animal manure, mushroomCompost provides nutrients as plants need them over the course of a season. It offers nutrients at a slower rate than fertilizer, and a faster rate than mulch. Compost also maintains soil structure when applied at least every two years.
(Fertilizer vs)Fertilizer offers nutrients that are available to plant roots right away. They can be organic or synthetic mediums. Fertilizer offers no soil protection.Fertilizer is a quick and short-term supply of nutrients (often in liquid or powdered form). It can be applied to give plants a growth boost in addition to compost, or every 10-14 days if used alone. Types: synthetic (liquid & solid), organic (liquid & solid)
A chart that explains the types of mulch, mulch vs compost, mulch vs fertilizer, compost vs mulch, the types of compost, compost vs fertilizer, fertilizer vs mulch, fertilizer vs compost, and the types of fertilizer.

Table of contents:

What is mulch?

It’s easy to decide if mulch is the right medium when you understand what it can do, the types there are, where to find it, and when to use it.

Mulch is most often any organic material that covers a soil surface. A blanket of mulch stabilizes the temperature, nutrient, and moisture levels of soil so living microorganisms can function. Organic or inorganic mulches can prevent erosion and reduce or eliminate weeds to relieve manual work.

Organic mulches also offer soil structure as they break down and offer more overall benefits than inorganic mulch.

Effective mulch can come in several shapes and sizes: Sheet mulch, coarse-shredded mulch, and fine-shredded mulch.

A list of mulch material types:

Mulch material typesWhere to find mulch materialHow to make mulch material
HayLocal farmers and ranchers who produce it; online markets offer spoiled hay for free or cheapGrow grasses or legumes to cut, dry, and store for use as hay.
Straw (whole or shredded)Local farmers and ranchers; online markets, local connectionsGrow grain such as rye, oats, wheat, etc thresh and collect the seeds, then collect the stalks, dry, and store them for use as straw.
Leaves (whole or shredded)Under any tree(s) in autumn, or collect full leaf bags in any neighborhood. (check the public local pickup schedule online and do your pickup within days before the city does).Rake and collect leaves from your property or roadways through local forests (never take leaves from a forest floor).
WoodchipsLandscape suppliers, host a dump site for local hydroelectric companies.Buy a woodchipper and chain saw to cut and stack brush, or any sized wood your woodchipper can cut and run through the chipper into a pile.
BarkLandscape suppliersChop down dead trees, take the bark off of firewood
Pine needlesGarden storesCollect pine needle droppings on privately owned property
Paper sheetsReuse cardboard from shipments, collect filled paper leaf bags each fall from neighbors, buy rolls of paper, use old newspaperFinding and reusing paper is more practical than making it yourself
Plastic sheetsReuse old greenhouse floor material from local nurseries to avoid buying brand-new plastic, buy recycled vinyl tarps, or offer to recycle local lumberyard tarps that they would otherwise throw away.Finding and reusing plastic is more practical than making it yourself
Fresh green materialOn-site: thick grasses, piled plants of any kind, or wide leaves such as banana leaves, comfrey leaves, or rhubarb leaves.Intentionally grow plants for the purpose of chop and drop.
A chart that explains what material to use as mulch, where to find the materials, and how to make the materials.

Where to apply different types of mulch

(Plus pros and cons)

Different sources of mulch are more or less suitable for particular circumstances. Below, they are detailed.

In general, mulch is best applied to permanent plantings rather than temporary annuals. Mulch ties up nitrogen to decompose which is less of an issue for perennials since they can tap into mycelium networks and aren’t required to mature in a single season.

In perennial settings, mulch is a long-term and passive source of slow-release nutrients as it slowly becomes compost.

Mulch also has its place in annual settings too! Read on to explore the options.

(More information about mycelium networks is in the compost section of this post.)

Hay and straw are the most common mulch used for non-permanent plantings, especially where trees are lacking.

  • They are low-cost to produce or buy.
  • Since small bales are easy to transport, move by hand, and take apart; they are often chosen to mulch vegetable gardens and grow potatoes. Both also last 1-2 growing seasons before they break down and need replenishment.
  • Applying straw or hay as mulch in a vegetable garden is physically easiest when growing in single or double rows.
  • Shredded straw or hay is easier to use in wide beds or denser planted situations. (Mounding a wide bed of potatoes and trying to prevent damaging the plants became pretty tedious that one time I didn’t have shredded straw)
  • Both are rarely used to landscape or beautify a property.
  • Hay and straw are attractive to spiders that benefit a garden. In some areas, rodents such as voles and moles are also attracted to either hay or straw which can damage crops until snakes find their way over to help balance the issue. If predators such as snakes control the rodent population of your landscape; droppings from all of them will benefit your plants passively.
  • Shredded hay or straw can be less attractive to rodents as smaller particles settle with less space.

Leaves make an all-purpose mulch that is generally quick to break down.

  • They are low-cost to gather, free to pick up from neighbors, and are not typically found for sale.
  • Leaves are high in mineral content and are beneficial in most circumstances, however, the difference you may consider is whole versus shredded leaves.

Whole leaves:

  • Smother the ground for weed-free pathways, but be cautious when wet as they can become slippery
  • Protect delicate perennials from chills by mounding leaves around them (rosemary for example) so they survive the winter. (Keep space between leaves and plants for base airflow and to ensure water can reach the ground)

Shredded leaves:

  • Mulch fall-planted garlic with a thick layer of shredded leaves for maintenance-free garlic. Garlic and other bulbs have the energy to grow through a thick layer of shredded leaves but not through a thick layer of whole leaves due to matting.
  • Shredded leaves break down faster than whole leaves and allow water to easily reach the soil beneath.

Woodchips are beautiful and most commonly used in permanent landscapes.

  • They take a long time to break down before they are considered compost—a perfect source of long-term food for perennials plants.
  • Mushrooms colonize woodchips in order to break down and you can inoculate fresh chips with edible gourmet mushrooms.
  • Woodchips allow new plants to establish themselves without competition by preventing weed seeds from landing in soil and germinating
  • Established weeds can grow through woodchips, so sheet mulching may need to be a partner to smother unwanted plants before applying woodchips.

Paper sheets are good for permanent application in permanent plantings.

  • Smothering established weeds for permanent spaces
    • Pathways: Laying sheet mulch before your desired mulch (such as woodchips) for paths extends the time before weeds begin to take over again. I’ve learned that mulched pathways don’t exist without yearly upkeep. Mulch eventually breaks down into a medium that plants love to grow. If you have a lot of pathways to maintain it can become too cumbersome to use
    • Food forests and perennial landscapes: to create a food forest or landscape design we need to replace naturally occurring plants with ones we desire. Sheet mulch clears the way and allows new plants to establish.
  • Sheet mulch doesn’t look beautiful and is often covered with woodchips
  • Preventing new weeds
    • Lasagna gardening: sheets are often used to make a lasagna garden but aren’t necessarily considered “mulch” in this scenario.

Related post: What kind of material is best for sheet mulching?

Plastic sheets are good for temporary weed termination for turn-around crops or permanent “flooring.”

  • Smothering weeds temporarily
    • Used to solarize an annual grow space to prevent the need for tillage by killing weeds with heat and light deprivation
    • In a single space, a tarp is laid to terminate weeds and old crops. Then it’s removed for a fresh round of food crop or cover crop.
    • For a headstart in spring, the heat from black plastic “mulch” can help cold-climate growers get a head start on planting. It temporarily smothers early-growing weeds while heating the soil quicker so you can transplant or seed earlier.
  • Permanent weed-free flooring or pathways
    • Greenhouses often line the pathway rows with plastic to minimize upkeep in the greenhouse.
    • Plastic laid as permanent weed suppression for pathways (both indoors and outdoors) can increase plastic pollution in your environment.
    • Be sure to bury the edges of any permanently laid plastic material to minimize tripping hazards.
    • As an effective weed suppressor, black plastic doesn’t regulate soil temperatures the way organic mulches do. Since it absorbs heat, early bolting (flowering) of crops from the stress of excessive heat can be a challenge in summer.

Fresh chop and drop is a regenerative way to smother weeds and grow soil at the same time.

  • Living pathways are easier to maintain than mulched pathways. In our experience, woodchip pathways take more energy to produce than living paths.
    • Low-growing ground cover crops (such as white clover) are an easy, almost no-maintenance option.
  • Dense and diverse polycultures are their own form of mulch
    • A dense polyculture is a diverse arrangement of wanted plants all growing close together. Weeds don’t grow because all space is occupied. You need to be able to identify all the plants to pick and choose what to chop and drop versus what to leave be.
    • The greater variety of plants reduces competition by growing companions together that occupy different root-zone levels. This ever-changing system thrives simply by allowing a mix of annuals, biannuals, and perennials to live out their lifecycles. The mix of plant types can be self-sustaining.
    • Vegetable gardens that are solely annuals need rich soil and ongoing amendment to sustain their demands in dense arrangements.

Related post: 3 Keys To Correctly Mulch Any Tree (What To and Not Do)

What is compost?

It’s easy to decide if compost is the right medium when you understand what it is, when to use it, and the ways it can be made.

Compost is a decomposed state of any organic matter including plants or animal manure. The activity in compost results in plant-available nutrients, beneficial microorganisms, and soil structure. All are significant for hosting an environment that grows healthy plants.

Many gardeners grow food successfully by producing and using compost to feed plants alone. (More details about organic gardening are in the sections below.)


The nutrient potency of finished compost depends on the age.

Compost is considered “finished” when the bacterial activity has completely consumed the wet/green/nitrogen-heavy tissue available. Signs of completion are when soft tissues and clumps are no longer present.

At this stage, compost is full of available nutrients needed by plants and will continually be consumed by fungi until it becomes humus—a carbon-rich substance generally lower in available nutrients than fresh compost.

Compost is an intermediate stage of the final deconstructed product (humus/carbon) that all constructed organic matter becomes.

Humus (carbon) is crucial for hospitable soil structure and nutrient retention. Remember that time in science you learned that carbon bonds with other molecules? Carbon clings and holds nutrients and water molecules. So even if many nutrients get used up or leached away—healthy soil contains plenty of humus.

In established and undisturbed soils; fungi (mycelium) rapidly grow underground and create networks that transport nutrients to plants in need.

Pretty amazing!


The rate of decomposition is affected by material type, material ratio, and moisture and oxygen levels.

Different types of materials break down at various rates.

  • Soft-tissue plant matter is often “green,” wet, and high in nitrogen which bacteria love to consume in moist and aerobic environments. Active aerobic compost piles (also known as the “hot composting” technique) are able to deconstruct in as little as 2-3 weeks!
  • Woody materials are broken down at slower rates primarily by fungi. The bigger the wood; the longer decomposition takes. Due to surface area exposure wood chips break down much faster than logs.
  • Animal manure is processed plant matter rich in nitrogen and fibers. The nutrient content is too strong for fresh garden application. Bacteria and fungi need at least a year to work together and decompose before it’s balanced with humus creation.

“Mushroom compost” isn’t a type of material to be composted—since it is already compost. I want to quickly clear up any confusion around this medium so you can make informed decisions for your garden. Mushroom compost is made from any raw material that mushrooms were previously growing in. Mushrooms for human consumption are often grown in animal manure, grain, straw, or wood and once these mediums are “spent” (consumed) they can be sold as “mushroom compost.”

This article was originally published on foodforestliving.com. If it is now published on any other site, it was done without permission from the copyright owner.

Moisture and oxygen play a big role in the speed of making healthy compost. Moisture is essential for all levels of life to function which includes microorganisms such as bacteria. Aerobic composting allows fast-acting bacteria to thrive and take advantage of oxidation but requires more manual effort for the gardener to maintain.

When to use compost (instead of mulch or fertilizer)

Sometimes compost is limited and it’s a good idea to reserve the precious resource for the places that need it most.

Finished compost is beneficial when applied to any setting at any time of the growing season to improve all soil conditions. Annual vegetables particularly benefit since they have high nutrient demands to grow to maturity within the time of a single season.

Since compost is broken down to the point that nutrients are readily available to plants, and humus is underway—you can’t go wrong when applying compost.

If you grow both annuals and perennials; the most affordable and efficient option is to reserve mulch for perennials and reserve compost for annuals.

Related post: When & How to Use Compost as Mulch (For Best Results)

Which is better mulch or compost?

The best choice between mulch and compost depends on your goals. We’ve seen the results first-hand and recommend both mediums in different areas.

Compost is better for growing nutrient-dense plants or producing fruit and flowers in a short amount of time. Mulch is better for suppressing weeds and retaining moisture. Both compost and mulch build soil health and structure.

For annuals, compost it is. They get one year to grow and need the food now. Mulch will deliver food too late and even shorten the growing season. Mulch keeps soil cool and spring already takes too long to warm for the average gardener on the edge of their seat. Fresh mulch also isn’t plantable, so it would need to be removed. Finished compost can host transplants and sprout seeds no differently than soil therefore it can be more efficient to apply compost without mulch.

Mulch makes sense in a vegetable garden if it’s your chosen form of weed suppression.

Ultimately, perennials and mature landscapes are in demand! So maybe mulch “is better” because the ideal system it’s applied is closer to simulating a forest? Let us know your thoughts by leaving a comment!

Can you mix compost and mulch?

You can freely mix any organic medium and eventually it will all become compost and later humus. Mixing finished compost with fresh mulch is a good idea if the outcomes align with your goal.

You can mix compost with mulch if you want to increase the size of your compost pile or amend perennial plants. Mixing mediums won’t suppress weeds like a layer of pure mulch would. Available nutrients of compost will also become unavailable as the mulch starts its break down journey. 

Only a blanket of pure mulch can deter weeds from growing. Compost will be less nutrient-dense when mixed with mulch than on its own. A mix of the two will both increase moisture retention.

Mixing compost and mulch is basically creating an unfinished compost. It may be better to use the compost you have where fertility is needed and start a new compost with mulch as an ingredient, or apply mulch alone where weed suppression is desired.

What is fertilizer?

It’s generally understood that fertilizer is a medium that feeds plants, much like compost, and even mulch. But they do have major differences even though some gardeners blanket compost or any nutritious organic medium as “fertilizer” too.

Fertilizer is a nutrient-containing medium derived from organic or synthetic processes. Various fertilizers have distinct ratios of plant nutrients for a particular focus. All-purpose fertilizers are a balance of nutrients that all plants need while many other types with focused priorities exist.

Some fertilizers focus on plant stages. Nitrogen and potassium are for vegetative plant growth and phosphorus is for fruit production.

Other fertilizers focus on specific, and even singular nutrients. Some organic compounds are higher in some nutrients such as nitrogen-rich chicken manure but still contain a mix of other beneficial chemicals. Single-nutrient fertilizers are synthetically made since all organic material comes with a variation of multiple nutrients.

A desire for such specific fertilizer was born when efficient but imbalanced mono-cropping and 100%-harvesting systems became a massive norm. The nutrient content of our soil becomes depleted and disproportionate when we grow and harvest giant patches of nitrogen-loving brassicas, for example.

Specific crops tend to take more or less of certain nutrients and since we often grow patches of heavy nitrogen-feeding crops such as brassicas, and fertilizers can restore that particular chemical.

Unfortunately, mono-copping practices and synthetic fertilizers are damaging the self-sufficient cycles of the earth.

Fortunately, organic fertilizers and the way we use them do not have such environmental consequences.

Examples of organic fertilizers include; bone meal, blood meal, fish emulsion, kelp, banana peel water, coffee grounds, compost tea, etc

When to apply fertilizer (in relation to compost or mulch)

Apply organic fertilizer while plants are actively growing every 10-14 days to boost their vigor. Fertilizer is like a supplement; the main course (mulch or compost) provides substance to maintain healthy soil. The supplement is an added drink of bonus nutrients that isn’t always necessary in a sustainable system.

If building soil is the goal of your garden, I recommend that you never use synthetic or “organic-based” fertilizers. Both are synthetically derived and kill off essential microorganisms in soil.

Fertilizer does not build soil. Fertilizer is an immediate-acting feed for plants. If your garden relies solely on fertilizer to grow food, your soil will deplete and become lifeless dirt.

Do plants grow faster with fertilizer or compost?

Since compost doesn’t display immediate results, it’s easy to question that maybe fertilizer is simply more effective. With time, the opposite has revealed the truth when instant gratification is out of the picture and long-term sustenance is the goal.

Compost is more effective at maintaining healthy soil than fertilizer. Fertilizer is better at feeding plants nutrients quickly if needed. However, if plants are growing in healthy soil, nutrients are available. Fertilizer is limited to feeding plants and does not sustain or build soil.

Sustainable-focused home gardeners tend to stay away from fertilizer altogether because they focus on building soil by composting a variety of organic materials. Some make their own concoctions with spare time as a boost.

Should I use fertilizer or compost?

The deciding factor between using compost or fertilizer depends on the costs you wish to incur as a gardener.

Compost is all any self-sustainable gardener needs to grow healthy plants. Some gardeners use multiple fertilizers after testing their soil to amend it with specific nutrients. The best-performing plants and soil run on both compost and homemade organic fertilizer.

Testing soil is an added expense to the gardener, and synthetic fertilizer has shown detrimental consequences on our environment.

But not all fertilizers are created equal—compost and fertilizer can be a team!

Organic fertilizers and compost work wonderfully together. Over time, compost becomes less nutritious while slowly becoming humus. Humus is predominantly carbon which can bind and hold fertilizer nutrients. Plants benefit from both by using a greater variety of available nutrients as needed.

What various gardeners choose to use

The best compost, mulch, and fertilizers are made from what you have available to you.

Here’s what everyday gardeners are saying about what they use:

  • Robert has coffee every morning and tosses the spent ground into the garden. He estimates 1200 lbs have gone in over the last 30 years.
  • Kate’s garden relies on compost and mulch exclusively. Compost goes in when she prepares for planting and mulch goes down after plants have sprouted to suppress weeds. Unused beds for a season get compost and mulch on top at the same time to rest until ready for planting next spring.
  • Kelly uses aged woodchips and manure from her chickens. She uses these as compost because she produces them and knows exactly what went in them.
  • Brett uses homemade kitchen-scrap compost and leaves because it’s all free. He also manages worm bins for worm castings to amend potted plants and tops them with woodchips to retain moisture.
  • Susan makes compost using plant-based kitchen scraps, grass clippings, shredded paper, leaves, woodchips, ashes, and manure from rabbits, chickens, and cows. She gathers material every fall and tills it in every spring.
    • She goes on to explain that these additions have improved her soil structure, Ph balance, and soil biology. Without her current process, she experienced depleted soil, and weak plants susceptible to insects, disease, and fungus.

Which is better compost, mulch, or fertilizer?

GoalBest mediums
Suppress weedsMulch
Build healthy soilMulch, compost
Nourish plants 1-2 years later, but for multiple seasonsMulch – apply a layer annually
Nourish plants for a season or twoCompost – apply annually
Nourish plants immediatelyOrganic fertilizer
Retain moistureMulch
Stabilize soil temperatureMulch
Prevent erosionMulch, (or seed the area with ground cover)
Kill soil biology and end up with dirt over timeSynthetic fertilizer
A chart that reveals the best mediums to choose for the goals you may have

Related post:

When & How to Use Compost as Mulch (For Best Results)

Does sheet mulching really work? When it does (and doesn’t)

Do you put anything under mulch? Yes (and No…)

Rachelle

While Rachelle's hands are clean for the keyboard, she enjoys writing and designing creative content and resources. You will most likely find her outside planting a cabbage, foraging berries for breakfast, and collecting herbs for year-round tea or making food.

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