9 Reasons to Use Compost as Mulch This Year
Mulch is essential for a healthy garden. It protects, insulates, and feeds the soil, creating an ideal home for budding crops. No matter the plants you’re growing, applying compost as mulch has a wealth of benefits for your yard. Join native plant gardener Jerad Bryant to discover nine top reasons for using it.
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Compost is like mulch and fertilizer in one; it contains nutrients like fertilizer, and it improves soil quality like mulch. It’s the perfect blend of organic matter, plant nutrients, and soil critters. Though it feeds plant roots, it has a wealth of benefits for the soil food web that extends beyond your crops.
Not only does compost help your garden, but the process of making it positively impacts the site. You’ll convert kitchen scraps, grass clippings, and yard debris into a black, crumbly, and fertile soil amendment. You’ll avoid filling landfills with waste that decomposes readily in the environment.
To make compost, use a hot or cold pile system, or consider using an Earth machine, a tumbler, or a wooden paddock to hold the stuff. There are many ways to convert waste into mulch—which method is best for you depends on your yard, how much space you have, and how much waste you manage.
So, without further ado, here are nine reasons you should use your compost as mulch this season.
Insulate Plant Roots
During winter, frosty weather can threaten perennial crops. Shrubs, trees, and veggies like rhubarb and asparagus benefit from mulch applications during autumn. The thick layer insulates your plants’ roots, protecting them from cold temperatures, ice, snow, and excessive rainfall.
When using compost as mulch, add it in a two to three-inch-thick layer. This depth is perfect for insulating, feeding, and protecting the ground without snuffing out tender seedlings or winter crops. Avoid piling it up near the stems, and rake it to distribute it evenly throughout the site.
The same is true for spring. Late spring frosts can threaten sprouting annuals and perennials. If you plant them into a thick layer of the stuff, you set them up for success during the earliest stages of their lives.
Deliver Nutrients
Like fertilizers, compost contains plenty of plant nutrients like nitrogen, phosphorus, and potassium. It also has secondary nutrients and micronutrients, like sulfur, calcium, and magnesium. The exact nutritional content will vary depending on the materials you put into it.
Compost is a mix of nitrogen-rich and carbon-rich materials. For every shovelful of nitrogen-containing “greens,” as they’re called, you’ll add two shovelfuls of carbon-containing “browns.” Every scoopful of greens gets two scoopfuls of browns.
To know for sure what your mulch contains, consider a soil testing kit to see what nutrients are inside your compost. It’ll also tell you the pH levels so you can amend them properly. This material tends to be acidic, and applying it can be harmful to areas that are already acidic. Knowledge is power, and this is especially true in the garden!
Retain Moisture
Perhaps one of the most alluring reasons to implement a composting system is to preserve moisture during hot, dry weather. Mulch traps water, holding onto it until the plants need to drink. Compost is especially moisture-retentive because it contains lots of humus.
Humus is a valuable soil by-product that forms when microbes, worms, and larvae eat organic matter. They emit humus, a porous and absorbent particle. The more humus your mulch has, the more moisture-retentive it will be.
This benefit is most prominent during the summer months. Without mulch, garden soils quickly dry, erode, and degrade. They’ll be poor sites for crops and wildflowers. If you don’t have a steady supply of compost, consider using leaf mold, straw, or a similar mulch to deliver similar results.
Inoculate the Soil
Because compost relies on fungi, bacteria, and archaea, you inoculate your soil when you add it to the ground. These microbes are incredibly beneficial; they break down large particles, convert unusable nutrients into types that plants can utilize, and they partner with plant roots to deliver the resources they need.
You might know of bacteria and fungi, but what about archaea? These tiny living things are similar to bacteria and fungi, though they’re slightly different. They tolerate extreme conditions, and they convert waste into nutrients for plants.
Bacteria help decompose organic matter, while fungi have a range of benefits. Certain types, like mycorrhizae, partner with plant roots. They exchange nutrients for sugars from the plants, forming a symbiotic relationship with your crops.
If you suspect the soil microbiome is weak or sparse, adding compost is a superb way of boosting microbial life. Adding two or three applications a year is a great way to maintain high levels of beneficial microorganisms.
Provide Habitats for Animals
Just as compost houses microorganisms, it also hosts a wide array of ground-dwelling critters. Worms, beetles, butterfly and moth larvae, crickets, and bees are some of the many animals that hide in open piles. Add the mulch to your beds to introduce these critters to the garden.
Worms are one of the most beneficial critters, as they form tunnels underground. These tunnels fill with air and moisture after the worms leave. When plants are thirsty or hungry, they reach into these tunnels with their roots and access what they need.
Other critters, like larvae and beetles, provide food for other predatory animals. These predators help lower pest populations, controlling unruly insects so you don’t have to worry about them. The more compost you use, the more space there will be for these creatures to thrive.
Improve Soil Quality
Adding microbes, soil critters, and nutrients to the dirt enhances its quality. After many years of adding compost, your garden soil will be healthy, fertile, free-draining, and water-retentive. Sandy sites will grow more absorbent, while those full of clay will grow more well-draining.
If your garden is full of perfect loam, compost is still beneficial. It’ll maintain a healthy site and ensure a constant flow of nutrients, moisture, and energy to the plants that need it most.
A layer two to three inches thick is perfect. As it degrades and breaks down, it will sink lower in the soil. Replenish the site when the mulch sinks, degrades, and exposes the earth below.
Stifle Weeds
Alongside protecting crops and feeding the dirt, mulch stifles weed seeds and seedlings. It also allows for easy pulling—compost creates a soft soil that plant roots come out of easily. If seedlings do sprout, you can catch them before they produce seeds to limit their spread.
When using this amendment to suppress weeds, you may add a layer thicker than three inches. Use a thick depth only if there are no crops, shrubs, or trees growing on the site already. A too-thick layer of mulch can smother their roots instead of protecting them.
Some weed seeds survive longer than 100 years! Always having a layer of mulch is key in preventing them from sprouting.
Recycle Waste
Composting not only helps your garden, but it also benefits the planet! Diverting things like kitchen scraps, grass clippings, and paper products from landfills to compost piles helps reduce carbon and methane emissions.
You know what they say—reduce, reuse, and recycle! Composting is one of the best ways of reducing waste and giving it back to the environment.
Though many things are compostable, some things aren’t! Avoid adding dairy products, meat scraps, and bones if pesky rodents are active in the area.
Compost is Free!
I love composting because it’s easy on my wallet! Instead of spending tons of money on amendments from garden centers and plant nurseries, you’ll have a free source of compost mulch at home that’s readily available whenever you need to use it.
This year, instead of buying potting soil, I planted onions, broccoli, and cauliflower directly into compost inside containers. They love it! They’re thriving with strappy leaves and budding florets, and I’m sticking to my budget instead of spending money on mulch.
If you want to grow plants in your compost, let it cure for a month or more before planting crops. The curing process allows the nutrients to level out so they don’t overwhelm the plant roots.
