If you ask any seasoned gardener their least favored part of gardening, you’ll likely hear the word “weeds.” In this post I shared my method of preventing weeds before they start. Part of that method — as in any sustainable non-chemical weed control — is the use of a weed barrier. In my garden, and in most backyard gardens, that weed barrier is mulch.
Mulch has many purposes. 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.
You do have a choice in what type of mulch you use. I have tried four different types of mulch in my garden — wood chips, pine needles, hay, and straw. In this episode of the Beginner’s Garden Podcast, as well as the post below, I share the benefits and drawbacks of each type. Armed with this information from the beginning, you can make the best, most informed decision on how you’ll mulch your garden.
Click below to listen to the podcast episode or continue reading:
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. 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. I will say from my experience, as I’ve incorporated organic practices of managing insects in my garden, squash bugs have become less and less of a problem each year, despite continuing to use wood chip mulch.
Do Wood Chips Tie Up Nitrogen in the Garden Soil?
I’ve heard many viewpoints on whether applying fresh wood chips to the garden will rob your garden of nitrogen that the plants need. Here’s my experience: 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 resources will say that pine needles will contribute to an acid 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 had a problem with even my naturally-acidic soil.
Hay Mulch in the Garden
One year I ran out of wood chips and decided to try hay. I had read horror stories about how hay can deposit weed seeds in your garden but I also read an equal amount of research saying that if you lay it on thick enough the seeds can’t germinate anyway. (This was one helpful article.)
But I never had any problems, and hay 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’ve found so far.
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. After hearing about Jill Winger’s experience where hay mulch poisoned her garden, I’m more cautious to recommend this method. Although I did not have any issues when I used they hay I purchased from my farmer’s co-op, there is a risk if you do not know the source of the hay.
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.
Straw Mulch in the Garden
Whereas hay is a collection of grasses harvested from a field, straw is the stalks of a wheat crop. Supposedly, straw has fewer seeds. Costing about the same amount of money, I’ve found straw covered almost the same amount of area that hay did, yet it was easier to apply.
However, I did not find straw to be as effective of a weed barrier as the other methods, and in fact, I found more weeds deposited in areas where I used it.
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 hay and 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.
Potential Chemicals. Unless the straw comes from organically-farmed wheat, it’s likely chemicals have been sprayed on straw at some point in its growth. This is something to keep in mind if you are trying to garden as organically as possible.
Not as effective as weed control. I completely stopped using straw in my garden as a mulch, simply because I found it to be the least effective at suppressing weeds. I know other gardeners use it and find it helpful; I just haven’t had that experience myself.
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. With the exception of pine needles on my walkways, I have transitioned to using them almost entirely. 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?
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Hi Jill. We use pine shavings in our stables and I can get the used shaving for free. Would the shavings/horse manure mix be suitable as mulch?
Pine shavings mixed with manure are an excellent addition to your garden. I put them in my compost pile to let them break down a bit before putting them on my plants, but I think it’s worth trying it as a mulch, too. Just don’t mix it into your soil; let it break down naturally. That said, horse manure should only be placed on your garden if you’re certain the horses haven’t eaten any grass or hay treated with herbicides. I’ve heard horror stories of tainted horse manure killing a garden. But since they’re your horses you’ll have a good idea of what they’re eating.
Good morning Jill:
I purchased black colored mulch to act as a cover for my Dahlias. I like the dark colored bark as a background for the beautiful Dahlias. This is my first year trying this type of colored mulch. I’m concerned about the benefits or drawbacks. Some of the black Dye (?) came off on my hands.
I have never done any research on colored mulch. I personally don’t use it and wouldn’t on my edible food garden, but I wouldn’t have a problem using it with a strictly flower bed. I bet the contrast is beautiful with your dahlias!
Wondering what type of chips you use. Pine.
I’m not sure. When we buy in bulk, we get them from a local lumber mill, so pine would be a good assumption. When we get them from a tree service, I imagine there are lots of different types.
How do you plant rows of seeds if not tilling in the chips?
I rake aside the mulch temporarily. Then after the seeds have sprouted and grown to about 6″ high, I pull them back around the plants.
Would baled pine shaving work? I don’t have horses any longer but use the pine shaving on muddy paths so my dogs won’t track mud in the house. The baled shavings can be purchased at our local feed stores.
Possibly. I have never used that so I can’t speak to it personally. The only concern I’d have is that they might have the potential to get matted down in wet weather, causing mold and even preventing moisture to penetrate if it gets too matted. If that’s what you have on hand, I’d say to try it but watch out for those things. Also, don’t ever mix it into the soil (same with wood chips), as they will take nitrogen from the soil as they break down.
I have a question for putting mulch in my raised garden (I’m a newbie). Do I put mulch in the bottom as well as the top? So it would be mulch-soil- mulch? Or just at the top? How many inches of mulch do you want at the top for your garden?
I’m not sure that it’s necessary to add it to the bottom. If you’re thinking it would help with weed control, perhaps. Or look at something like cardboard boxes. (I’ve never done either… most of the weeds I’ve encountered were from existing weed seeds not due to them growing from the bottom.) Whatever you do, don’t mix it into the soil. As far as how many inches, I recommend 2 inches on top of the soil.
This may be a silly question – but would mulching a raised garden bed impact root vegetables that you have planted in it (radishes, carrots, onions, etc.). Thanks in advance!
Not negatively at all — at least not in my experience. In fact, I’ve noticed that my root crops, particularly onions, benefit from mulch because that mulch regulates the soil temperature. Onions will bolt with increasing heat, which happens more quickly in raised beds. Another thing is root crops don’t compete well with weeds, so mulching will benefit them by keeping the weed pressure down.
Hi Jill, what do you do with the wood mulch at the end of the season since you don’t till it with the soil.?
I have used salt (marsh) hay before and it was a good option because the seeds don’t sprout and it’s not treated. It’s not quite as pretty though And I’m not sure if it’s available around the country.
I leave it on the soil over the winter to break down. It helps prevent erosion, and you’d be surprised at how much of it actually does break down over the course of the year (I estimate 3/4 of it). Then, when it’s time to plant, I move the wood chips aside and then back around the transplant or seedling. Of course, by the next season, I have to add more.
Generally good comments but I wonder if you have experienced what happens to cardboard in or on soil after a short time. I did just that a while ago and then one day I was readjusting the soil and partly decayed cardboard. To my horror I had created a cellulose smorgasbord for all the termites in the area. I had created a magnet for these damaging little critters. Drop your guard a little and they do untold damage – especially if they get into a house
Interesting. I’ve never seen that, but I’ve also never looked underneath, as I’ve always just let the cardboard boxes decompose into the ground. My garden is also well away from my home; the only time we’ve had issues with termites is when using fresh wood chips next to the house. It’s definitely something to keep an eye out for, especially if a garden is close to a home. Thank you for pointing that out.
You didn’t mention grass clippings. Do you not recommend it?
Good question. I have never used grass clippings, which is why I didn’t include it; however, I do believe it’s a good option when used correctly. First, you have to make sure the lawn hasn’t been sprayed with any sort of herbicide. Second, don’t put fresh clippings on the garden, as they can matt-up and form a barrier of sorts in wet conditions. Let them dry out a bit and then sprinkle them on as mulch. I have a friend who has used them with great success.
What about leaf mulch? I’ve read that cut leaves mixed with grass (to add nitrogen) is an excellent mulch. What’s your take on this?
Absolutely! I didn’t include it in my list because I don’t have deciduous trees and personally haven’t tried it. BUT I know many gardeners use it as their primary source of mulch. You’re right to get it to a finer texture, and if you mix grass clippings with it, make sure the lawn hasn’t been sprayed with any pesticide or herbicide.