9 Best Ways to Mulch Your Raised Garden Beds
Mulch protects, feeds, and insulates tender crops. It’s an essential part of a healthy garden! Learn the nine best ways to mulch your raised beds alongside seasoned grower Jerad Bryant.
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Mulch is a term for soil coverings that help plants thrive. They can be organic or inorganic. Organic types decompose readily, while inorganic ones like plastic sheets break apart and stay in the soil for decades without decomposing.
Organic mulches are best for home gardens; they require minimal upkeep or maintenance. They break down over time, adding beneficial nutrients and particles to existing soils. A prime example is compost—it’s one of the best mulches you can use!
How to mulch your raised beds depends on what materials you have available. Use whatever you have lying around; fall leaves, grass clippings, and plant debris are suitable options. No matter what you use to mulch, you’ll help your plants survive and thrive during the growing season.
Without further ado, here are the nine best ways to mulch your raised garden beds.
Compost
Compost mimics natural processes in a small system. It harnesses bacteria, fungi, and archaea that live in the soil, unleashing them on organic waste. They eat the waste particles and turn them into humus, a valuable soil particle.
You can think of compost like the forest floor—trees, plants, and animals die and fall to the ground. Leaves fall on top of them, and they decay underneath the leaf litter. Eventually, soil microbes recycle all the organic matter into humus, creating soft, porous dirt throughout the forest.
An easy way to compost is with a standalone pile. Simply layer a shovelful of nitrogen-rich or “green” materials with two or three shovelfuls of carbon-rich or “brown” materials. Turn the pile daily and keep it as moist as a wrung-out sponge. You’ll have fresh compost to use in a few weeks!
When adding compost, ensure the layer is two to three inches thick. Avoid super thick layers, as they’ll suffocate tender plant roots. After the layer decomposes you may add another helping of compost.
Leaf Mold
Leaf mold is similar to compost, except it’s made entirely of leaves! It’s an excellent material, as leaves are abundant in regions with deciduous trees and shrubs. Simply make a pile three feet high by three feet wide, water it, and turn it daily. After a few weeks, you’ll have usable leaf mold for your garden.
Because this mulch consists entirely of leaves, it’s much more carbon-rich than compost. It’s a good amendment for raised beds where woody shrubs or trees grow. Woody species need lots of carbon to create strong structures, while fleshy species need nitrogen to grow green and tall.
Many community gardens offer free leaf mold in exchange for volunteer hours. Call up your local community and see if there’s some available, or ask your neighbors that compost if they have extra leaves you can use.
Grass Clippings
Grass clippings are abundant in yards with lawns. A weekly or biweekly mowing generates heaps of grass! Rather than throwing it in the trash or yard waste bin, you can reuse it to create a closed loop in the garden.
Closed-loop gardening implies that no nutrients escape the yard. You recycle waste into new forms that plants can use, saving you time and money. Simply collect the clippings, spread them on the raised beds’ soil surfaces, and water them so they stay put.
Though grass clippings benefit the garden, too many can cause growing issues. Piles of grass decay anaerobically, or without oxygen. They create slimy, smelly messes! Grass with seed heads attached can proliferate in your garden. For best results, spread the grasses evenly throughout the site, use clippings without seed heads, and avoid placing them in thick layers.
Hay and Straw
Hay and straw are similar materials perfect for mulching a raised bed, though one is better! Whereas hay is the best product for feeding farm animals, straw is ideal for animal bedding and mulching gardens. Hay often contains seeds of weeds and legumes that can sprout when you spread it in your yard.
Straw is much safer to use than hay. It rarely contains seeds and consists of dry grain stalks that are hollow and brittle. When you layer them on top of the soil, they provide protection and insulation as they decay. The decomposition process incorporates the straw into the soil, boosting its fertility, structure, and drainage capabilities.
You may use hay if you have it in abundance; just note that you’ll have many weed seedlings to pull during the growing season. It’s best to use hay for feeding animals and straw for mulching garden beds.
Fall Leaves
Leaves are perfect for mulching raised beds! They drop to the ground in abundance as summer turns into fall. Though they seem like a nuisance, they’re extremely beneficial natural resources that return essential nutrients to the soil.
When you mulch with fallen leaves, you create a habitat space for overwintering insects and small critters. Ladybugs, fireflies, and springtails love hiding in the spaces between the leaves. As your garden awakens in spring, insect predators and pollinators emerge from the leaves to help reduce pests and pollinate flowers.
Instead of mulching fallen leaves, you may also turn them into leaf mold for use on top of the soil. Leaf mold benefits the soil quicker than whole leaves, though it holds less space for beneficial insects.
Other uses for fall leaves include leaf tea, lawn fertilizer, and garden art. Whatever you do, don’t let them go to waste! Instead, repurpose fall foliage to help your garden thrive.
Paper
Paper is made from trees, so it decays readily in natural settings. You may use shredded paper as mulch as long as it’s free from harmful processing chemicals, inks, and dyes. Glossy paper tends to have inorganic compounds that struggle to break down. Only use paper you know is 100% safe for the garden.
To start, shred all your paper to create a mass of clippings. Paper decays quickly in moist, sunny conditions, so you can apply plenty of it on your beds. Make layers two to three inches thick like you would with compost. Add more after the layer decays to provide a consistent supply.
Paper is recyclable, though recycling requires energy and resources to turn raw waste into new materials. Rather than using more energy on waste, let the paper break apart in the soil. It’ll provide carbon to woody species while it insulates tender crop roots.
Cardboard
Cardboard, like paper, consists of woody byproducts that we process into boxes, containers, and sheets. It has many uses in gardens aside from being a possible mulch material. Only use cardboard that’s free of harmful chemicals and synthetic dyes.
Growers use this material to replace lawns with beds; they place cardboard down, put soil or compost on top, and plant seedlings into the dirt. The cardboard snuffs the growing grass, decays, and creates rich dirt for the roots to penetrate.
As with paper, it’s also beneficial to chop the cardboard into small pieces before adding it to the beds. This prevents it from snuffing your growing plants and allows air and water to seep into the ground.
Worm Castings
Worm castings are extremely helpful! They’re full of primary nutrients like nitrogen, phosphorus, and calcium, while they’re also rich in secondary ones like sulfur and calcium and micronutrients like iron. They provide the necessary elements to your plants when they need them most.
Nutrition isn’t the only thing they help with; they also contain high levels of bacteria and fungi that turn waste into plant nutrients. They’ll inoculate the soil with these beneficial microbes that help your crops sprout healthy fruits and vegetables.
Because worm castings are “hot,” meaning they’re rich in nutrition, they may cause burning on young plants. Ensure you follow proper application rates and avoid adding more than an inch or two on top of the dirt. Aim to keep application rates at 10% of the total mass.
Mix the castings with organic mulches like compost, straw, or leaf mold to avoid adding too much. If you’re purchasing this material, follow the instructions on the package for proper application rates.
Composted Manure
Like worm castings, composted manure is a waste product of animals. Rather than worms, it comes from cows, chickens, and pigs. Fresh manure isn’t a good product for the garden, as it may have harmful diseases. After composting, however, the manure turns into a nitrogen-rich amendment.
As with castings, you want to avoid adding too much manure to the dirt. Excess amounts can cause adverse effects in young and weak plants. Mix it with compost, or add a thin layer onto the beds and incorporate it into the soil.
Another way to find this amendment is to ask around. Some homesteaders have chickens, which means they have ample chicken poop! Ask them for a few buckets, and compost the stuff in a pile before adding it to your beds.
