Organic Mulch for a Vegetable Garden | Top 13 Mulches

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A garden that mimics nature is bound to be successful. If you walk into a forest, the earth is covered with mulch in the form of leaves in various stages of decomposition. The soil underneath is dark, rich, and teeming with life. Here are some ideas to mimic nature with organic mulch for a vegetable garden.

There are so many organic options for mulch but I’ve limited this list to the top 13! Unfortunately, due to the excessive use of all kinds of chemicals in modern day agriculture and manufacturing, care must be taken with where you source your mulch.

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Do your homework before adding anything to your vegetable garden. This list is in no particular order because the best mulch for me is different from what may be the best for you. Oftentimes, the best organic mulch for a vegetable garden is the one that you can acquire easily, affordably, and/or locally! 

#1 Compost

A well decomposed compost that is weed free is absolute magic to the soil. It’s feeding the soil and covering the soil. It’s also dark, so it’s perfect for use over heat loving crops like tomatoes, peppers, watermelon, and corn.

Compost can be made at home, or it can be purchased. If you are purchasing compost and want the assurance the compost is safe to use, I recommend using certified compost. You can find a source near you HERE.

#2 Leaves

As I mentioned above, leaves are a natural choice for mulch because nature uses this in the forest to cover the ground. Leaves have so many nutrients in them and are a fantastic mulch because they don’t have the threat of introducing weed seeds to the garden.

Whole leaves can be used but they are slower to break down and can make a mat that doesn’t allow much aeration. The best option is chopped and slightly decomposed leaves.

#3 Plant Waste

When growing food, oftentimes a large plant is grown and only a fraction of the plant is actually eaten. Some examples of this are corn, grains, cucumbers, squash, and certain root crops. 

When the edible part of the plant is harvested, the rest of the plant material can be used as a mulch. It can decompose in place, or even be pushed into the walking paths.

If the plant is diseased, you probably would want to remove it from the garden but for everything else, it can definitely function as ground cover and an organic mulch for a vegetable garden.

I highly recommend reading Ruth Stout’s book, How to have a Green Thumb without an Aching Back, for more information on using plant material as a mulch in place. 

It eliminates a lot of the work of removing plant material from the garden and composting it, you let it slowly compost in place. The negative of this method is it’s not pretty but it is cheap, easy, and does the job well!

Included in the category of plant waste mulch is locally available by-products like cottonseed hulls, cocoa shells, shredded corn stalks, and buckwheat hulls. You would want to double check with your source that they are not genetically modified.

#4 Hay or Straw

Hay and straw are fantastic mulches. However, you must use caution and make sure your source of hay or straw has not been treated with an herbicide. 

Sometimes hay and straw can be confusing to differentiate so here are the definitions.

Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. 

Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder. Source

I personally use hay that was sourced and bailed on our property so I know it is safe to use. For years I heard that hay was terrible to use in the garden because it has so many weed seeds. 

One year, out of desperation, I used some as a mulch and to my surprise, I had no weed problems. I layered it on thick. It was my most weed free part of the garden not only that year, but also in future years!

I’m amazed at how often I debunk common ideas and hearsay about gardening with personal real life experience.

#5 Paper

Recycled paper is a good option for an organic mulch for a vegetable garden. Newspaper is a great option because the inks used are vegetable based and safe for the garden. 

Any brown paper that is not coated and doesn’t not have colored or glossy inks is likely to be safe. 

Bleached paper is not a good organic option due to traces of dioxin in the finished paper. Dioxin is a by-product of bleaching paper pulp with chlorine. Dioxin is a strong carcinogen even at low levels. Source

I use an OMRI listed paper as a mulch in my garden as an alternative to plastic. I just started using it a few months ago, but I like it so far. It can be found HERE. It is expensive, but I think it will be worth it for the time saved not having to weed.

One thing I’ve learned already is to weigh the sides down by layering mulch on it so the wind doesn’t rip it off. I use wood chip mulch but whatever is available to you would work. 

#6 Grass Clippings

If you grass clippings down in a deep layer, weeds will not penetrate through. But beware of unwanted weed seeds from clippings. I learned that from personal experience.

Another thing to be aware of is, grass decomposes quickly and can heat up then burn plants. To avoid this make sure the grass is not pushed right up against the plants or laid on top. 

#7 Living Mulch

Instead of adding a dead and decomposing mulch, another idea is to use a living ground cover as mulch. 

The beneficial microbial population thrives in living plant roots. Therefore, a living cover creates a diverse ecology of life in addition to all the general benefits of mulch, like covering the soil, reducing weeds, and reducing erosion.

On a personal note, I have used living mulch in garden beds while vegetable crops are grown and it is very tricky to accomplish successfully. 

Timing of living mulch maturity, height, and whether the roots will compete for nutrients with the vegetable crop are all things to consider. It definitely can be done, but it takes careful consideration.

The safest use of living mulch is in garden pathways, however you need to mow and maintain it. According to Jesse Frost, in The Living Soil Handbook, a mixture of clovers and perennial ryegrass is a good place to start. Creeping thyme, chamomile, and other low-growing perennials could be mixed in as well. 

#8 In Situ Mulch

In situ mulch is mulch grown and used in place. The best options for creating large amounts of biomass are cereal crops like rye, oats, wheat, sorghum, or sudan grass. These mulches can be mixed with other beneficial cover crops then chopped and tarped, or crimped and tarped to kill the crop and leave a mulch in place.

This is my favorite organic mulch for a vegetable garden since the work is minimal and the only thing I outsource is the seed. There is no heavy lifting and scooping of mulches into place, it’s already there.

Another benefit of in situ mulch is some cereal crops, like winter rye, have an allelopathic effect, meaning the weed seeds are less likely to sprout. It also means vegetable seeds will be less likely to sprout, so it’s best used for pathways or for transplanting into it. 

More information on cover crops, when to plant, and the best mixes, can be found HERE.

#9 Wood Chips

Wood chips can make a great mulch and keep the soil cool. It is common for wood chips to be used in garden pathways. 

It is less common for wood chips to be used on a garden bed because wood chips can tie up plant-available nitrogen in the soil. 

Generally, layering the wood chips on the surface of the soil is ok, but the problem of wood chips stealing nitrogen comes when wood chips are mixed into the soil. 

I personally have used wood chips on the surface of a garden bed, then raked them away after seasons end without an issue. 

Another practice is to let the wood chips age first, then add them on top of garden beds. 

Thankfully wood chips from tree trimmings are not tainted with chemicals. Stay away from treated wood sawdust and chips. Another caution is to not use black walnut wood chips. They contain small amounts of a compound called juglone that can inhibit growth of some types of plants. 

A good mix of wood chips from several types of trees is generally the best for the garden. Even if a small amount of black walnut wood was mixed in, it would likely have very little effect. 

#10 Pine Needles

If you have access to a large amount of pine needles to use as mulch they are a great option! There is a common myth circulating that pine needles will make your soil more acidic. That is false.

The only time pine needles are acidic is if they are slightly green and taken directly from the tree. Within a few days as the pine needles turn brown and get dry they are not acidic at all. Source

#11 Seaweed or Kelp

One thing that makes me so jealous of those who live by a coastline is the ability to access seaweed easily from the source. Seaweed is incredibly rich in minerals. A study of seaweed from the National Library of Medicine says:

Seaweeds are… rich in macro-elements and trace elements, with a mineral content at least 10 times higher than terrestrial plants and reaching 20-50% of its dry weight. Source

Seaweed and kelp are different things, but they have a lot of the same benefits. I’ve never seen either seaweed or kelp available anywhere sold as mulch.  That may be because I live far, far away from any coastline.

It’s more likely to see it sold dried and pulverized for use as a soil amendment. But if you live near the sea, and can collect it yourself, it would be a great option.

Barbara Damrosch in the book, The Garden Primer, adds the caution to “wash off the salt first.” 

#12  Bark Chips or Shredded Bark Mulch

Tree bark mulch is slower to break down than most mulches and is high in nutrients. Pine bark mulch is the most common type for sale in big box stores or garden nurseries.

I’ve used pine bark chips around my blueberry plants and it was fantastic. The only caution is to make sure your source of bark mulch is not dyed. 

Also, pine bark floats up easily and can move around quite a bit during significant rain events.

#13 Cardboard

Cardboard can be a good option as organic mulch for a vegetable garden. However, would need to be combined with something to cover it and weigh it down. It is commonly used to smother crops, grasses, or weeds then covered with another mulch.

Use of cardboard in the garden is a hot topic because there could be potential harm to the garden depending on a number of factors. Let’s break these down.

According to the National Organic Program (NOP) cardboard is allowed for organic use if the following criteria are met:

Cardboard is considered to be a type of paper and therefore must be made from recycled materials. The cardboard cannot be printed with glossy or color inks. In addition, the cardboard must not be waxed or have been treated with fungicide.OMRI Generic Materials List, page 12 Source

So according to NOP, cardboard is ok for use as a mulch, as long as there is no wax, no colored or glossy inks, and no fungicides. 

Even if you follow the NOP standards to the letter, there may still be some risk.

Do your research about cardboard before applying and make an educated choice

The new threat of using cardboard stems from the use of PFAS or “forever chemicals”. From my understanding it is mostly on pizza boxes and take-out food boxes since it makes the containers more resistant to oil and water.

If cardboard has this on it or in it, the idea is that even after the cardboard biodegrades, the chemicals will leach into the soil and never go away. PFAS chemicals have been linked to certain health risks.

All that being said, you could find health risks in almost anything man made so take all that information and make your own educated choice!

I did a lot of research about the safety of cardboard and one of the best articles that was fact based can be found HERE.