Organic Mulch: A Complete Guide to The Best Natural Mulches
INSIDE: Looking for the top organic mulch? This is the ultimate guide to great natural mulches. Pick the best mulch in just a few minutes with my free mulching chart.
Imagine if you could magically minimize the need to weed, water, and fertilize your garden.
Well, your fairy garden mother (aka organic mulch) is ready to wave her wand over your garden and grant your wish!
Organic mulches create a cozy blanket over your garden soil.
That magical blanket protects your soil from drying winds, blistering sun, and the 40,000 dandelion seeds your neighbor blows into your yard with their lawnmower every weekend.
And there are lots of great natural mulches to choose from.
But picking the right one can feel overwhelming when you’re at the store eyeing all the organic mulch options.
Let’s see; there are wood chips, colored wood, straw, shredded bark, pine straw, and maybe even seed hulls!
Then you see compost and wonder, “Can that be used as mulch, and what about shredded leaves or lawn clippings?”
Well, I have answers to those questions and the ones you’ve not even thought of yet…
Let’s find the perfect mulch for your garden!
What’s in this article:
- What is the best organic mulch?
- The benefits of organic mulch.
- The disadvantages of organic mulches.
- Choose the best organic mulch – what I recommend.
- Types of organic mulch I don’t recommend.
- Frequently asked questions about organic mulch.
- Download a free mulching cheat sheet so you can choose the best mulch for your garden.
Heads up: If you buy something after clicking a link in this post, I’ll earn a small commission. I only link to products I’d recommend to my best friend.
What is the best organic mulch?
With so many great natural mulches to choose from, how can you know what’s the best organic mulch for your garden?
- To quickly find the top organic mulch for your situation, download my mulch comparison chart and then check out the types of organic mulch I recommend.
- If you’re not sure that organic mulch is the best choice for your garden, keep reading to learn about the benefits of organic mulch, and then use my three-step method to choose the perfect mulch for your yard.
Organic mulch is any type of mulch that was once living.
- It’s an eco-friendly mulch.
- It’s made of things like wood chips, bark, and straw.
- All organic mulches break down and improve your soil structure—some more than others.
Related: Where to buy organic seeds.
The advantages of organic mulches
Organic mulch does many good things for your soil and plants.
Here are the benefits of using organic mulches:
1. Organic mulch suppresses many types of weeds
Organic mulch is one of your best weed control tools.
Organic mulch keeps the soil underneath it shaded. This prevents most weed seeds from germinating because they typically need light to germinate.
And since mulch keeps the soil loose and moist, pulling the few weeds that pop up is a lot easier.
2. Adds organic matter to your soil
As organic mulches decay, they add organic matter to your soil.
When your soil’s micro- and macro-organisms come up to the surface for a snack, they pull that organic matter back down with them when they travel back into your soil, delivering it right to your plant roots.
3. Can reverse or prevent soil compaction
A thick layer of mulch helps disburse your weight as you walk through your gardens, which helps to prevent compaction.
As large soil organisms like earthworms and pill bugs pull the decaying mulch into your soil, they help glue your soil particles together, which creates air pockets that help to reverse soil compaction.
3. Gives your landscaping a finished look
Mulch will give your garden bed a finished look by filling in the empty spaces around plants.
4. Reduces your water bill
Water evaporates slower when an organic mulch covers your soil surface.
With increased moisture retention, you’ll be able to water less, and your plants will have a steadier stream of water available to them.
As a bonus for joining my weekly newsletter, download a free Mulching Cheat Sheet. And choose the right mulch for your yard in 3 easy steps!
5. Keeps your plants clean
Natural mulches help to reduce soil splash-back on plants, which cuts down on soil-borne plant diseases.
6. Protects your soil from temperature swings
Organic mulch acts as an insulator. In the winter, it can keep plants from heaving out of the ground and keep your soil cooler during the summer heat.
If you live in a cold climate, organic mulch might not be the best choice for your heat-loving vegetables since the mulch will prevent your soil from warming up. Plastic mulch would be a better choice.
7. Can prevent soil erosion
Because organic mulches break the fall of water when it rains, they stop topsoil from washing away.
8. Protects trees from lawnmowers and weed eaters
Spreading organic mulch around trees planted in lawns creates a barrier between the tree and your lawnmower or trimmer.
Related: Discover the facts about using corn gluten meal for weeds.
Like everything in life, there are some cons to organic mulching.
- First, organic mulches need to be topped off periodically.
- They’re bulky and hard to transport. And it takes work to spread them.
- They may not be the best choice for slopes because they tend to get swept away in heavy downpours and blown around in strong winds.
- Organic mulch isn’t the best choice for some types of plants, either.
- Think desert-adapted plants like cacti or succulents.
- Or plants that need good drainage, like irises, lavenders, and most Mediterranean herbs.
- Those plants will do better under gravel mulch or with no mulch.
- And finally, organic mulch alone may not be enough to control some perennial weeds.
Before we get into the details of each type of organic mulch, download a free, printable mulching cheat sheet. It walks you through my easy three-step process for choosing the best mulch for your garden.
Wood Chip Mulch – Highly recommended for all ornamental gardens
Wood chips can come in many sizes. Some smaller-sized wood chip mulches would better be described as “ground” wood mulch.
The smaller the chip size, the more likely it is to stay in place. The larger chips are lighter, blow around more, and can float away in strong rainstorms.
Wood chip mulch is best for mulching trees and shrubs, flower beds, perennial flowers, orchards, and walkways in flower and vegetable gardens.
Depth: 2-4 inches, depending on the size of the chips or how finely ground it is. Bigger chips can be applied more deeply.
Advantages: Is usually attractive. Adds organic matter – this is especially helpful for perennial plantings where you can’t easily amend the soil.
It also lets in water, prevents evaporation of water, suppresses weeds well, moderates soil temperature, and is free of weed seeds. Smaller chips or more finely ground wood are less likely to blow or wash away than larger chips. It doesn’t readily compact. And finally, it reduces and often reverses soil compaction.
Disadvantages: Larger chips can blow or float away. It must be topped off — top-dress larger chips every 1-3 years, smaller chips every 1-2 years.
- I recommend uncolored wood mulch. Read my review of colored wood mulch.
- Don’t create mulch volcanoes when you mulch trees.
- Don’t install wood chip mulches over landscape fabric.
- Wood chip mulch isn’t recommended in vegetable beds next to plants but is fine to use in vegetable garden pathways.
Will wood chips tie up nitrogen in my soil and steal it from my plants? Good news! This is a myth.
- If the mulch sits on top of your soil, any nitrogen tie-up will be tiny and won’t affect your plants.
- But, if you turn it under or till wood chips into your soil, it’ll tie probably tie up some nitrogen. So, if you don’t turn it under, wood chip mulch WON’T rob your plants of nitrogen.
- In annual flower beds, rake off the mulch before planting, and re-mulch after your plants are in to avoid turning it under and creating that possible nitrogen deficit.
Straw Mulch – Best organic mulch for vegetable gardens
Straw mulch is the best organic mulch for vegetable gardens. It’s especially helpful for keeping your soil cool in the warmer months. If you want to warm your vegetable garden soil, see plastic mulches for vegetable gardens.
Depth: 2-3 inches.
Advantages: It lets in water, prevents evaporation of water, adds organic matter, suppresses weeds well, moderates soil temperature, and can be turned under at the end of the season.
Disadvantages: It can blow around easily. It may have weed seeds in it. It has to be replenished annually. And it’s flammable. Some say it’s not super attractive.
- Purchase straw, not hay. Hay has lots of weed seeds in it! See this article about possible dangerous pesticides in straw.
- Pre-sprout weed seeds in your straw by watering the bales a couple of weeks before spreading the straw. Remove any that have sprouted as you spread it.
- Get tips on how to mulch your vegetable garden.
Corn Stalks and Corn Cobs – Recommended
This mulch is best for vegetable gardens.
Depth: 2 inches.
Advantages: Corn stalks make a good winter mulch.
- They let in water, prevent the evaporation of water, add organic matter, suppress weeds, and moderate soil temperatures.
- They’re free of weed seeds and can be turned under in the spring.
Disadvantages: They can mat or blow away. Shredded stalks aren’t the most attractive mulch. It may not be readily available where you live.
- Stalks should be shredded, and cobs should be ground up.
- Mix the stalks with straw to prevent matting.
- If you want to use stalks from your own garden in the spring, you’ll need space to store them over the winter.
Cotton Burrs – Recommended
Cotton burrs are best for vegetable gardens and are recommended if you can find a source of burrs from a producer who doesn’t use a lot of pesticides and doesn’t chemically defoliate the plants.
Advantages: They let in water, add organic matter, prevent water from evaporating, suppress weeds, moderate soil temperatures, and are weed-seed-free.
Disadvantages: Cotton may have had a lot of pesticides applied to it.
Notes: Don’t use burrs from chemically defoliated plants.
Evergreen Boughs – Recommended
Evergreen branches are best to use on perennials or small shrubs that need protection over the winter.
Depth: Several layers.
Advantages: Good for insulation during the winter to prevent heaving and frost damage.
Notes: Remove them in the spring when the soil warms up and the threat of frost has passed.
Green Manure/Cover Crops – Recommended
Cover crops improve your garden soil and reduce weeds. Examples include ryegrass, winter rye, oats, buckwheat, barley, and annual clovers.
Cover crops are best for vegetable gardens and orchards.
Advantages: They let in water, add lots of organic matter, prevent water from evaporating, suppress weeds, and moderate soil temperatures while they’re growing. As a bonus, they attract many beneficial insects when they flower.
Disadvantages: You won’t be able to grow vegetables while you’re growing a cover crop.
Notes: You must turn them under or cut them down before they go to seed. Otherwise, they’ll spread and become a nuisance.
Grass Clippings as Mulch – Recommended
Grass clippings are best used on your lawn if you have a mulching mower.
- Mulching your lawn clippings can reduce your lawn fertilizer needs by up to 25%.
- The next best place to use them is your compost pile.
- You can also use them in your vegetable garden if you’re careful about how you apply them.
Depth: up to one inch.
Advantages: They let in water, prevent evaporation of water, add organic matter, they’re typically free of weed seeds, and they can be turned under at the end of the season, and they’re free.
Disadvantages: It can mat or blow away. When it mats, it creates a stinky, slimy mess. Allow the clippings to dry out first, and apply them in thin layers. Add additional thin layers as they decompose.
Notes: Don’t use clippings in your garden if they were recently sprayed with weed killer or if the lawn has gone to seed or has many weeds. Bag these clippings instead.
BONUS: Download my free printable as a bonus for joining my newsletter: Mulching Cheat Sheet: Pick the perfect mulch.
Leaf mulch (shredded leaves) can be used in either your vegetable garden or ornamental garden.
Depth: 2 inches.
Advantages: It lets in water, prevents evaporation of water, adds organic matter, it’s typically free of weed seeds, can be turned under at the end of the season, and leaves are free.
Disadvantages: Can easily mat or blow away. You must collect them in the fall and have a place to store them over the winter if you want to use them in the spring. They can look messy.
Notes: Mix shredded leaves with straw mulch to prevent matting.
Living Mulch – Recommended
Living mulch, especially perennial groundcovers, works well in ornamental gardens or orchards.
Advantages: They’re attractive. They let in water, prevent the evaporation of water, add organic matter, suppress weeds somewhat, moderate soil temperatures, and they won’t blow or wash away.
Disadvantages: Can take over parts of your garden if you choose an aggressive ground cover. Some require maintenance, like annual mowing or pruning.
Related: Examples of living mulch.
Nutshells, Cracked or Ground – Recommended
Nutshells are best for ornamental gardens.
Depth: 2-3 inches
Advantages: It lets in water, prevents evaporation of water, suppresses weed growth, is free of weed seeds, and moderates soil temperature. Some are attractive, and some are slow to decompose.
Disadvantages: These mulches may be expensive unless you have a nut processing plant nearby. Some shells can have sharp edges. It can blow around easily. It’s not suitable for slopes. And some can look messy.
Notes: Examples include: Pecans, Peanuts, and Hazelnuts. Avoid using walnut shells around plants sensitive to juglone.
Pine Straw – Recommended
Pine straw (aka pine needles) is best for ornamental plantings and orchards. They can also be used in your vegetable garden.
Depth: 1.5 – 3 inches.
Advantages: It lets in water, prevents evaporation of water, moderates soil temperature, suppresses weeds somewhat, and lasts a long time. It’s free of weed seeds and provides good winter protection for fall transplants because it resists compaction.
Disadvantages: It can’t be turned under at the end of the season. It’s a fire hazard. It can look messy. It adds little organic matter. And it doesn’t suppress weed as well as other mulches like wood chips or straw.
- Pine needles don’t affect soil pH, contrary to popular myth. So, they won’t help acid-loving plants by changing the soil pH.
- You may only need to top off this mulch every few years.
- If you have large long-needled evergreens, you can harvest your own mulch.
Seed Hull Mulches – Recommended
Seed hull mulches (from cotton, buckwheat, cocoa beans, and rice) are best for vegetable gardens.
Depth: 1-2 inches, 1-inch max. for cocoa hulls
Advantages: Some hull mulches are attractive. They all let in water, prevent evaporation of water, add organic matter, suppress weeds, moderate soil temperature, are free of weed seeds, and can be turned under at the end of the season. Some are more attractive than others.
Disadvantages: They can blow around because they’re lightweight. Cotton may have had a lot of pesticides applied to it. Cocoa mulch may get moldy if it’s used in humid or damp conditions. It can also form a mat and can have high levels of potassium in it.
Notes: All hull mulches must be replenished annually.
Newspaper and Cardboard – Recommended
Newspaper and cardboard can be used anywhere you want to suppress weeds.
- Newspaper, a few sheets thick
- Cardboard: 1 layer thick
- Always wet the newspaper as you lay it down, and overlap the edges.
- Soak the cardboard before laying it down to be sure that both sides are wet.
- Cover the newspaper or cardboard with 2-3″ thick layer of either straw or woodchips.
- Keep the mulch and soil moist. Check to make sure that the newspaper and cardboard aren’t drying out.
Make choosing the best type of mulch simple. Download my FREE Mulching Cheat Sheet.
Coffee Grounds – Recommended with reservations
Coffee grounds aren’t good to use as mulch by themselves.
Depth: ½ inch
Advantages: Coffee grounds let in water, moderate soil temperature, and add organic matter. It can be turned under at the end of the season if you cover it with a second mulch that also can be turned under.
Disadvantages: Coffee grounds can compact and crust over unless they’re covered with another mulch. And layers thicker than ½ inch compact and crust over more.
- To use coffee grounds as a mulch, apply a half-inch layer. Cover that with a 3-4″ layer of coarse organic mulch (wood chips or straw).
- Don’t use coffee grounds near seeds; they’ll reduce germination rates.
- Don’t till un-composted coffee grounds into the soil.
- The best use for coffee grounds in your garden is to compost them.
Colored wood mulches are best used in ornamental gardens.
Depth: 2-4 inches, depending on the size of the chips.
Advantages: It moderates soil temperature, prevents the evaporation of water, is free of weed seeds, and adds organic matter. Some people find it attractive when it’s new.
Disadvantages: It fades to grey unevenly which can make topping it off more work than it should be. You may also find you have to top it off more often than natural wood mulch.
Compost – Recommended with reservations
Compost can be used in most gardens. Rock gardens and native gardens that need lean soil are the exceptions.
Depth: 1-2 inches, depending on how much organic matter you need to add to your soil. See the notes below.
Advantages: It lets in water, and adds organic matter. It can be turned under at the end of the season. Lets in water and adds organic matter. Commercially produced compost is free of weed seeds.
Disadvantages: Weed seeds will go crazy germinating in your garden if you don’t cover the compost with another mulch that suppresses weeds.
- Get an accurate soil test to see if you should add compost to your soil.
- 5-6% organic matter is the recommended amount.
- It’s best to cover the compost with a layer of another mulch like wood chips, straw, or leaves to suppress weeds.
Shredded Wood (gorilla hair mulch) – Recommended with reservations
Shredded wood or bark mulches (sometimes called gorilla hair) are best used in gardens with drip irrigation, or in wet climates.
Depth: 2-3 inches
Advantages: It moderates soil temperature, adds organic matter, prevents evaporation of water, and controls weeds. It’s free of weed seeds and is long-lasting.
Disadvantages: It compacts and forms a barrier against water.
Notes: Only use this type of mulch if you have drip irrigation set up under the mulch, or you live in a wet climate where rain will penetrate the mulch.
Bark Mulch: Chips or Shredded Bark
Bark mulches are expensive, tend to compact and form a barrier against water, and aren’t as good at conserving water as wood-chip mulch.
Wood chip mulch is the better choice because it breaks down fairly quickly and improves your soil.
Peat moss is a good soil amendment in certain situations but is a terrible choice for mulching. It blows away easily. It crusts over. It becomes hydrophobic when it dries out. And it’s not environmentally sustainable.
Salt Marsh Hay
Saltmarsh hay is a mulch available in the northeastern U.S. Salt marsh hay is harvested from ecologically sensitive coastal estuaries and flood plain areas. The continued seasonal harvesting of salt hay disrupts and damages these areas.
Sawdust and Wood Shavings
Put sawdust and wood shavings in your compost pile rather than use it as a mulch. It compacts, crusts over, and resists water. It shouldn’t be turned under as it’ll tie up nitrogen in the soil while it decomposes.
If you use it, before applying, mix one pound of nitrogen per 5 bushels of sawdust to prevent nitrogen tie-up in the soil.
Frequently asked questions about natural mulch
Should I use organic mulch?
You should use organic mulch if you want to improve your soil. If you live in a very windy area, garden on a slope, or struggle with mulch that floats away in heavy rains, then organic mulch might not be the best choice. Consider using an inorganic or living mulch in these situations. When mulching next to buildings, organic mulches aren’t the best choice. Use a non-flammable, inorganic mulch instead.
Where can I buy certified organic mulch?
It can be very difficult to find certified organic mulch or organically grown mulch.
The types of organic mulches that are the least likely to contain any pesticides or herbicides are going to be tree-based: shredded or chipped wood, shredded bark, and pine needles.
If you have a local landscape materials supplier, you should be able to get mulch like that in bulk at a cheaper price per cubic foot than you’d pay for bagged products.
What is a good organic mulch?
Choosing a good organic mulch depends on what you’re mulching. If you’re mulching your vegetable garden, straw is the best choice. If you’re mulching your flowers, shrubs, and trees, wood chip mulch is a great choice.
Is brown mulch better than red mulch?
A naturally brown mulch is better than red (dyed) mulch. All wood mulches turn silvery gray over time. But dyed wood mulches don’t lose their color evenly. So, undyed mulches tend to look better in their second season when compared to faded red mulch. If you want to use dyed mulch, choose a dark brown color, as it tends to last longer than red.
Can you put mulch directly on soil?
Yes, you can (and should) put mulch directly on your soil. Avoid using landscape fabric or barriers under mulch. They don’t prevent weeds and cause more problems than they solve. Organic mulches need to sit directly on your soil to improve it.
Should you remove old mulch every year?
No, you shouldn’t remove old mulch every year. As the mulch ages, it breaks down and feeds your soil. Just top it off to the original depth to improve your soil, save water, and suppress weeds.
Why should you not put mulch around your house?
You shouldn’t put organic mulch around your house or next to structures because organic mulch is flammable. To reduce fire danger, mulch around your house with rock or stone mulch.
With so many organic mulch options to choose from, it can be hard to know which one to pick! This cheat sheet will help you choose the perfect organic mulch for your garden in three easy steps.
- Focus on what plants you want to mulch.
- Choose the top three things you want this mulch to do for your garden.
- Once you have the answers to those questions, look through the list of mulches to find the perfect mulch for your needs. The chart includes details about 26 mulches. I grouped them by mulches I:
- recommend with reservations, and
- don’t recommend
Take the guesswork out of choosing the best mulch. Get your FREE Mulching Cheat Sheet now!
Here’s a sneak peek of your printable cheat sheet:
Now it’s your turn: what organic mulch did you choose off the list?
Share in a comment below!
Are there any organic mulches that I missed?
If so, let me know in the comments, and I’ll add them to the list.