Adding mulch to your garden is one of the best things you can do for it. Mulch is a multipurpose tool in the garden that helps with weed suppression, boosts water retention, minimizes soil runoff, and adds organic matter to the soil. Not bad for one component of the garden!
Organic mulches such as wood chips or leaves come from living things. These types of mulches will break down in the garden, adding to your soil. Inorganic mulches are ones like landscape fabric, plastic, or even rocks. These items can do the job equally well but will not contribute to your soil in the same way.
I dig into my favorite mulches to use in this episode of my podcast, Organic Gardening For Beginners. Have a listen!
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What is the best mulch for my garden?
We’ll go over each mulch in detail, as well as where to source them. But to get you started, here’s an overview for each type of organic mulch mentioned here:
|free and abundant,
long-lasting, very effective
|usually delivered in large amounts,
may need to wait for delivery
|free from your own yard,
good for seedbeds
|may contain weed seeds,
not an option for those without a lawn
|free from your own yard,
adds high-quality organic matter
|available mainly in fall,
may have to take the extra step to shred them
|lightweight, good for seedbed,
adds high-quality organic matter
|might have to drive to a store to collect it,
might be harder to find
|adds organic matter to soil,
can be made at home
|may not have compost at home,
may contain weed seeds
|very effective, can improve yield over
other types of crops
|not available to most gardeners
Mulch is a multipurpose tool in the home garden
If you’re not yet convinced that organic mulch is a massive help in your garden, let me give you a few more details that might change your mind. Then decide which will be the best type of mulch for you and your home garden based on the qualities of each type of mulch.
Suppresses weeds: When a 2-3 inch layer of mulch covers the garden, it prevents sunlight from reaching the soil’s surface, where weed seeds lurk. Without that sunlight, the weed seeds lay dormant instead of sprouting, reducing the amount of weeding you need to do, as well as minimizing competition for your garden plants.
The seeds that do get enough sunlight to sprout (maybe there are occasional gaps in the mulch or thin areas) are easy to pull out with a quick pass through the garden.
A few weeds here and there are so much easier to deal with than an entire bed of bare soil acting as a seedbed for weeds.
Retains water: A layer of mulch insulates the garden soil from losing as much moisture through evaporation compared to bare soil.
Additionally, organic mulches absorb water themselves. As the sun warms up the air, it will evaporate the moisture in the mulch first. Once the mulch is dry, then the soil below will start to warm under the sun, and water will evaporate and escape through the mulch.
This is a much slower process than when the sun hits bare soil and warms it more quickly since there isn’t a buffer. The result is a reduced need to water the garden, saving time and water while keeping the garden plants hydrated.
Minimizes soil runoff: When water hits a mulched garden bed, the water droplets are dispersed throughout the mulch, trickling down to the soil below. It hydrates the mulch itself and the soil, keeping the soil from splashing up onto the plant.
The barrier prevents rivulets of water, whether from a watering wand or rainfall, from carrying topsoil off your garden beds. It also helps keep newly sown seeds in place when they’re lightly covered with a layer of straw or grass clippings.
There’s no such protection with bare, unmulched soil, and the water’s impact is much more likely to carry soil off and out of the bed, leading to a washed-out garden.
Adds organic matter: Organic matter encompasses all the live and dead parts of soil, such as the plant roots, compost, and tiny microbes. Combine those things with the sand, rocks, and water that make up dirt, and you get soil.
Without organic matter, garden plants will have a much harder time growing abundantly and would rely heavily on fertilizer to flourish.
So it’s a good thing when your mulch contributes to your soil as organic matter. It happens in place as the mulch breaks down during the season and beyond. As you add more mulch the following season, you’re adding more future soil-building components.
Speaking of adding mulch, don’t feel like you have to take off old layers before adding a new one. Keep it easy, and learn more in this article, Should I Remove Old Mulch Before Adding More?
The best organic mulches to use
Alright, now you’re convinced that mulch is the best thing you can add to your garden, other than the plants themselves. Dig into what makes these the best organic mulches and get started incorporating them into your garden.
Don’t forget that you can mix and match mulches based on their purpose in the garden and which materials you have available.
The number one spot goes to wood chips. I’ve used wood chip mulch in my garden for years, and it’s never gone wrong. If you’ve done any research into using wood chips as mulch, chances are you’ve seen warnings not to use them.
The warnings stem from the fear that they will rob nitrogen from the soil as they decompose, thus denying your garden plants the nitrogen they need to grow.
Fortunately, those warnings are inaccurate (but persistent). Studies have since shown that when woodchips are spread on the surface of the soil, there’s no interference with the soil’s nitrogen levels, leaving your garden plants unscathed. You can dig into the full details in this article from Washington State University for more information.
To source wood chips for garden mulch, call your local tree trimming services and arborists and ask if they’ll drop off loads of wood chips after they’ve completed a job in your neighborhood. Dropping wood chips off saves them the trip and expense of taking them to the dump, so it’s unlikely they’ll say no.
I’ve gotten many loads of woodchips dropped off at various gardens over my many years of gardening, and they always get put to use. Just make sure you have room for the large truck to be able to drive under low-hanging tree branches, as well as clearance to tilt up the back of the truck for dumping.
Wood chips are a heavier mulch, so they are not ideal for seedbeds or over broadcasted seeds. Use them in beds with seedling transplants or established plants for best results. Keep a small ring around the plant stem clear of chips to avoid retaining too much moisture and encouraging mold or rot.
Walkways are another fantastic place for woodchips. They soak up excess rainfall, suppress weeds, and eventually break down to build more soil for the garden.
Turn your lawncare chore into mulch for your garden with grass clippings. These are a nice, lightweight option if you want to mulch a seedbed or a bed of established plants.
On a seedbed, the grass is light enough that it won’t prevent the seeds from getting light and pushing through. Just keep the mulch layer relatively thin until the seeds have germinated. Then you can add another layer to help keep the weeds down and hold in moisture.
The grass will break down relatively quickly, so as you mow your yard through the season, keep an eye on the level of grass mulch in your garden to see if it’s time to reapply.
Two essential factors for grass clippings as mulch:
Use organic, herbicide-free clippings: Don’t use clippings from a yard that has been sprayed with any sort of herbicide or other lawn chemicals. The grass could contain residue that then transfers to your soil.
The residue could prevent your vegetable or flower seeds from germinating, and it could contaminate edible crops such as lettuce that might touch the grass.
Use clippings from grass that hasn’t gone to seed: The last thing you want to do is transfer loads of grass seeds to your garden beds. The whole point of mulch is to prevent weeds, not encourage them, so make sure your grass hasn’t gone to seed yet when you cut it.
If your lawn has already gone to seed, compost those clippings and find a different mulch to use for now. Let the grass grow back and then cut it before it goes to seed.
Like grass clippings, leaves are an almost endless supply of mulch sources right from your (or your neighbor’s) yard.
One thing to keep in mind is that leaves are particularly abundant in the fall, which doesn’t do much good when you need a layer of mulch after you get the spring planting done. Long story short, using leaves as mulch takes a bit of planning to build up a supply.
In the fall, rake dry leaves into large garbage or lawn bags and store them somewhere they won’t get rained on. Or make sure the bags are tightly closed, as you don’t want a bunch of water getting in and turning your leaves into rotten mush over the winter.
You can use the leaves whole in your garden beds and paths. If you go this route, use a thin layer of just an inch or so. A thicker layer can prevent water from getting down to the soil below if the leaves clump together and become impenetrable by irrigation or rainwater.
You can shred your leaves before putting them in the garden to avoid this. To do so, you can run them over with a lawnmower and dump the bagged shreds in the garden.
Or, you can dump the leaves in a big garbage can, then use a weedwhacker to shred the leaves right in the bucket. With this method, many leaves will initially fly out of the bucket, so wear eye protection to avoid getting debris in your eyes.
In dry or windy climates, leaf mulch can blow away, so check on your garden beds after windy days to see if you need to add more leaves.
For even more information on using leaves, check out this post, Quick Tips For Using Leaf Mulch In The Home Garden.
Straw is a grass-like dried material that comes from the wheat harvesting process. Since the wheat seeds have been harvested from the stalks, there’s no need to worry about weed seeds popping up in your garden soil, unlike hay.
Hay is meant to be used as animal feed and does indeed have many grass seeds in it, so make sure you’re getting straw, not hay, if this is the best mulch for your garden.
Straw is a very lightweight mulch that is excellent for seedbeds. Just like grass, it’s easy enough for seeds to get the necessary light for germination, and there are gaps between the straw stalks that the sprout can grow through.
It’s also easy to scatter straw between young seedlings and clump handfuls of it around more established plants. I like to use straw around plants that might touch the ground, such as cucumbers or melons, since the straw stays a bit drier than another mulch like woodchips or compost.
For a free source, contact your local feed store. You can often get bags of free straw if you’re willing to scoop up the loose piles that are left behind from bales being removed from the stack.
It bears repeating: Make sure you’re putting down straw, not hay, or you’re in for a very tedious summer full of weeding.
Either finished or unfinished, compost makes an excellent mulch in the garden.
Unfinished compost can come from your home compost pile. Spread it out in the garden bed to finish breaking down right there, plus get the added benefits of mulch, such as weed suppression and moisture retention. In the case of compost, you’ll also get added nutrition and plenty of organic matter.
With unfinished compost, make sure there weren’t a bunch of weeds in the mix. Just like with grass clippings, you don’t want to introduce new weed seeds to your garden beds. Since the compost is unfinished, it didn’t reach a temperature high enough to kill the weed seeds, so they would undoubtedly sprout up in your garden beds.
On the other hand, finished compost should have cooked long or hot enough to kill any weed seeds. If you’re unsure if it qualifies as finished, visually check to see if you can identify intact plants such as grass stalks or pieces of roots. If not, and all you have is dark, crumbly compost, then you’re probably in the clear, even if it initially did have weeds in it.
Using compost as mulch might feel like you’re just adding another layer of soil on top of your existing garden soil. And in a way, you are. But, you’re still adding a barrier between the sunlight and any weed seeds that might be lurking at or under the surface of your garden bed.
Plus, the rich quantity of organic matter in compost will help retain moisture in the soil since the compost itself is almost like a sponge, able to hold water to percolate down to the soil below.
I’ve never used wool in the garden, but I have read about people using it successfully. This idea is only practical (and free, for that matter) if you have access to wool trimmings from your own sheep or someone you know. But if that’s you, then give it a try.
In this study done by Sustainable Agriculture Research and Education Projects, organic vegetable farm, Turner’s Farm, mulched a plot of eggplant, tomato, and peppers with wool from their sheep. They recorded data like soil temperature, soil moisture levels, and harvest yields compared to a hay-mulched plot with the same type of vegetables.
They recorded more stable soil temperatures, fewer weeds, and higher harvest yields with the wool-mulched crops compared to the hay-mulched ones. The plants also had higher nitrogen levels, so it looks like wool also adds a bit of fertility to the garden beds.
If you have access to wool, set up your own experiment and see if it boosts your yields, too.