Updated October 2021
If you ask any seasoned gardener their least favored part of gardening, you’ll likely hear the word “weeds.” Sure, we all will have to pull some weeds, but wouldn’t you rather prevent as many as possible?
To prevent weeds in a sustainable, non-chemical way, you’ll need to use a weed barrier. In my garden, and in most backyard gardens, that weed barrier is mulch.
Mulch has many purposes. These are just a few of the main ones:
It blocks sunlight, which inhibits the growth of unwanted weeds and grasses.
It helps maintain moisture levels, which prevents water stress in times of drought.
Natural mulch also breaks down slowly into the soil, depositing valuable nutrients for future plants and creating a habitat for beneficial organisms like earthworms, bacteria, and fungi.
The organic gardener has many choices in mulch, but over the years the ones I keep returning to are these:
Let’s explore the pros & cons of each of these types of mulch, and I’ll also mention why I no longer use hay as a mulch in my garden.
Wood Chip Mulch in the Garden
Wood chips are my favorite form of mulch. I’ve tried all the other methods below, but I always come back to wood chip mulch.
Benefits of Wood Chips as Mulch in the Garden
Free (potentially). I called my local tree service the summer before I began my first garden. When they were in my area, they were gladly willing to drop off dump-truck loads of wood chips from freshly-cut trees. If you don’t have time to wait for the tree service to deliver mulch to you, contact a your local municipality or a local lumber mill. Chances are you can obtain wood chip mulch from one of those places for free or for a small fee if you can haul it yourself.
Beautiful. This is a personal preference, but I enjoy the beauty of a garden mulched with wood chips.
Easily handled. All you need is a pitchfork and a rake and you can lay down the mulch quickly and easily. It’s still work, don’t get me wrong. But laying down the mulch and smoothing it out is easy and maybe even a little therapeutic.
Improves soil structure. The parts of my garden covered with wood chips for multiple seasons have developed a lighter texture, which is a huge benefit for my clay loam soil. In addition, the wood chips contribute to soil fertility as they break down over time.
Drawbacks of Wood Chip Mulch in the Garden
Timing. You are usually at the mercy of when the tree service happens to be in your area.
Pest haven. Wood chips can be a haven for some pests, such as squash bugs. On the other hand, they’re also a haven for beneficial ground beetles as well If pests like squash bugs are a problem with your garden when using wood chips, avoid using wood chips in areas where their host plant (like squash) are growing.
Do Wood Chips Tie Up Nitrogen in the Garden Soil?
I’ve heard concerns that applying fresh wood chips to the garden will rob your soil of nitrogen that the plants need. This is commonly accepted as a garden myth these days (more on that here).
But here’s my personal experience after using wood chip mulch yearly for almost a decade: as long as I apply the wood chips to the surface of the soil, I’ve never had any issues with stunted plant growth. At the surface level, where the soil meets the wood chips, nitrogen will likely be used to help break down those wood chips, but at the root level, this will not be an issue.
As long as you do not incorporate (till, heavily rake) the wood chips into the soil (ever, even at the end of the season), you shouldn’t have any issues.
Pine Needles as Garden Mulch
I’ve used pine needles, also known as pine straw, off and on in my garden, simply because I have an abundance of pine trees on our property. Although they aren’t my preferred method, they do have their advantages.
Benefits of Pine Needle Mulch
Free. If you live near pine trees, this is an obvious choice. In the fall when your lawn is covered in copper, rake the needles up and put them in a pile to sit over the winter. This is great exercise, let me tell you. (That’s my optimistic way of telling you this is a lot of work.)
Excellent barrier. Pine needles mat together easily, creating an excellent barrier. Once they are set down, they stay.
Slow breakdown. Pine needles won’t break down in one season like the other methods might. For this reason, I like pine needles on my walkways, which I keep constant from season to season.
Drawbacks of Pine Needle Mulch
Not easily spread. Because of their nature, they aren’t as easily spread as other methods. They don’t take to raking across the garden like wood chips do, and they are a bit cumbersome to apply.
Physically prohibitive: If raking pine needles is your method of acquiring them, this can be a hard task for a large garden. However, for small gardens, it is easily doable.
Do Pine Needles Make the Soil Acidic?
Some people are concerned that pine needles could contribute to an acidic soil. Others, however, contend this is only true for fresh pine needles. The pine needles you’ll be putting on your garden are not fresh. I haven’t noticed a problem with even my naturally-acidic soil.
Shredded Leaves as Mulch
I began using shredded leaves more and more since I bought a leaf shredder and I began obtaining leaves from a family member’s property. After a year, I can say it has become one of my favorite mulches in the garden.
Benefits of Shredded Leaves as Mulch
Healthier soil. I personally found that the plants that grew in beds where I used shredded leaves were healthier and more productive.
Retains moisture. While this is an attribute of all organic mulches to some extent, I found it to be fantastic at moisture retention, a huge plus in dry times.
Drawbacks of Shredded Leaves as Mulch
Difficult to source. If you don’t have deciduous trees on your property, these may be difficult to obtain.
Can matte down, causing rot in some plants. Some plants, like strawberries, don’t love shredded leaves because of their ability to retain moisture, especially during rainy periods. Personally, I haven’t found this to be the case but I have heard others caution about it. I used shredded leaves on strawberries, garlic, asparagus, onions, and other crops with no problems.
They need to be shredded. If you don’t shred the leaves, they will blow away (ask me how I know). Many people mow over them and collect them, but I found the shredder to be well worth the investment.
Straw Mulch in the Garden
Straw is comprised of the stalks of a wheat crop. It’s easy to apply and easy to obtain. But I didn’t find it to be as effective at preventing weeds as other methods.
Straw is supposed to contain fewer weeds, but, I found more weeds deposited in areas where I used it (likely due to seed heads remaining in the straw bales).
Benefits of Straw as Mulch
Easy to apply. Due to the density and length of the stalks in a bale of straw, I found straw much easier to apply.
Attractive. I still prefer my wood chips, but the shiny gold nature of straw lends an appealing look to a garden, especially in comparison to the dull look of hay.
Good choice for raised beds. Because of the cumbersome nature of applying pine needles, straw and wood chips were easier to apply in my 4′ by 8′ raised beds.
Drawbacks of Straw as Mulch
Hard to apply on a windy day. Because straw is so light, when applied on a windy day, it was hard to keep in place.
Less nutrient-dense. Straw is known to contribute fewer nutrients to the soil as it breaks down over time.
Not as effective as weed control. I use straw sparingly these days because I simply haven’t found it as effective as weed control. But it’s still one of my top options.
Hay Mulch in the Garden
Hay mulch is no longer one I recommend because unless you can find organic hay, the risk of poisoning your garden is too great (my experience was similar to this one). But if you can find a source of organic hay, it’s definitely an option to consider.
The year I used hay that didn’t poison my garden, it did an excellent job keeping weeds at bay. The only places weeds and grass got through was where I did not lay it on as thick. Here are some of the advantages I found.
Benefits of Hay as Mulch
Possibly free or cheap. If you know a farmer or can get your hands on spoiled hay, you’ll likely get this source for free or cheap. Otherwise, I bought my hay from the farmer’s co-op for $8 per bale. A bale goes a long way since it is rolled up tightly. One could easily mulch 3-4 raised beds.
Nutrient-rich. When hay breaks down into the soil it deposits a wealth of nutrients into the soil.
Excellent barrier. Matting down like pine needles, yet a little easier to work with, hay forms an excellent barrier for weeds. Although it is “puffy” when it is first applied, it quickly flattens, both to suppress weeds and provide a path on which the gardener can walk.
Drawbacks of Hay as Mulch
Cumbersome to apply. Although not as difficult as pine needles, it can be cumbersome to apply hay to existing crops. This simply means I can’t breeze through the task like with wood chips and straw. It just takes a little extra time.
Potential chemicals. From what I understand, almost all hay is sprayed with aminopyralid, so unless it’s organic, the hay probably has it.
Critter haven. Although I never found snakes in my hay, at the end of the season I did find voles. (At that moment I wished I had snakes to get rid of the voles.) Once I went back to wood chips, I never found voles in my garden again.
Which mulch will you choose in your garden?
Personally, after many seasons, I choose wood chips for the most effective weed control and its benefits in my garden. But I like using shredded leaves better for raised beds and pine needles for pathways.
But no matter which method you choose, the key is to apply it thickly. A layer 2 to 4 inches is ideal. If you find weeds or grass growing through it, apply more.
The main takeaway from this is simply to choose a mulch. Your garden will be more attractive, your work load will decrease with less weeding, and using one of these methods will over time allow your soil’s structure and fertility to be increased in the long-term.
What method interests you the most? Have you had experience with any of these?