Mulch is the landscaping practice of covering the soil in your garden, flowerbeds, or around trees. But it’s important to know how to mulch to get the most out of it. Properly putting down a couple of inches of bark chips, straw, or leaf mold helps slow weed germination, minimize soil moisture evaporation, and insulate roots from extreme heat and cold.
What is mulch?
Mulch is a layer of material spread over the soil surface in gardens, landscapes, flowerbeds, and other cultivated areas. It serves many different purposes and has numerous benefits. Mulch can be made from various materials, and the best for your situation depends on the desired aesthetics, needs of the plant(s) you are mulching around, and local availability.
Different kinds of mulch
While there are many types of mulch to choose from, all can be divided into one of two categories: organic or inorganic. This classification depends on whether the mulch is biodegradable or non-biodegradable.
According to Bert Cregg of the Michigan State University Extension, “From a plant-health perspective, organic mulches are preferred since they contribute organic matter to the soil and provide the most benefits.”
That doesn’t mean you have to go with an organic mulch. Both types have advantages and disadvantages, making it important to weigh your options carefully before deciding which is best for your project.
Note: Unsure if organic or inorganic mulch is the right choice? Our article dives a little deeper into the pros and cons of each, helping you choose which is best.
Organic mulch
Organic mulches are products that come from other living materials. Over time, they break down to slowly release nutrients like nitrogen, potassium, and phosphorus into the soil and improve the soil structure with the additional organic matter and beneficial microorganisms. Since they decompose, they need to be replaced periodically.
Organic mulch materials include:
- Straw
- Fresh or old hay
- Grass clippings
- Wood chips
- Tree bark
- Wood shavings
- Pine needles
- Tree leaves
- Compost
- Cocoa hulls
- Ground covers
For more in-depth information, head over to our article on the “10 Best Organic Mulches”.
Inorganic mulch
On the other hand, inorganic mulches are materials that do not break down over time. They still offer some of the same benefits, such as suppressing weeds and conserving soil moisture, but they don’t boost soil fertility or improve soil structure.
Some inorganic mulches have the added advantage of looking nicer, giving your yard a more decorative touch.
Common inorganic mulch materials include:
- Rubber nuggets
- Marble chips
- Pea gravel
- Slate chips
- River rock
- Seashells
- Reflective metal
Determining how much mulch you need
Mulches typically come in plastic bags and are sold by the cubic foot. So, to determine how many bags to purchase, you’ll need to first determine how many cubic feet of mulch you need to cover the area.
- Determine the mulching area’s square footage.
- To calculate the square footage of a square or rectangular space, measure the length and width of the area and multiply the numbers to get square feet.
- To calculate the square footage of a circular bed, measure from the center to the outside edge. This number is the radius. Then, take the radius and multiply it by itself (you want the radius squared), then multiply the radius squared by 3.14.
- To calculate the square footage of an odd-shaped area, try picturing circles, squares, and rectangles within the shape. Calculate the square footage of each imaginary shape and add them together.
- Add up the square footage of the individual mulching areas to get a total.
- Multiply the square footage by the number of inches you want to apply. Mulch should be applied 1 or 4 inches deep in most cases.
- Calculate how many cubic yards or cubic feet you need, depending on how you’re buying mulch. Bulk mulch is sold in cubic yards; bagged mulch comes in cubic feet, usually 1.5 to 2 cubic feet per bag.
- To calculate cubic yards, divide the number from Step 3 by 324. A cubic yard of mulch covers approximately 324 square feet of soil with 1 inch of mulch. This answer is how much mulch you need in cubic yards.
- To calculate cubic feet, divide the number from Step 3 by 12. A cubic foot of mulch covers approximately 12 square feet of soil with 1 inch of mulch. This answer is how much mulch you need in cubic feet.
Example:
After measuring, you determine you have 200 square feet of soil you want to mulch, and you want to mulch 3 inches deep.
- So 200-square feet x 3 inches deep = 600
- If buying in bulk: 600 divided by 324 is 1.85 cubic yards. Most nurseries or companies sell by the cubic yard, so you’ll need to round up and purchase 2 cubic yards.
- If buying by the bag: 600 divided by 12 is 50, meaning you’ll need to buy approximately 50 cubic feet of mulch. Assuming a bag from your local big box store contains 2 cubic feet of bark mulch, you must purchase 25 bags (50 cubic feet divided by 2 cubic feet per bag).
Note: Need help figuring out how much this project will cost? We have a helpful pricing guide that explains how much mulch costs.
How to mulch your yard: Step-by-step
Laying mulch is a straightforward job, but I will give fair warning about two things.
First, it’s likely going to hurt your back and maybe your glutes and legs. Moving bags around (or hauling wheelbarrow loads) the yard and bending over to spread it is physically taxing. Second, you’re going to get dirty — really dirty, depending on the type of mulch you’re spreading. Expect to have dust and dirt in your hair, your ears, up your nose, and between your toes, even if you’re wearing socks and shoes.
Let’s get into the dirty work with that out of the way.
- Clear the area of weeds, trash, sticks, or other debris. If possible, remove the weeds by hand, making sure to pull the roots out.
- Use a landscaping rake to level the mulching area, smoothing the soil to create a nice flat surface.
- (Optional) Cover the ground with landscaping fabric or a weed barrier for extra weed control. Some people lay sheets of newspapers down since they decompose quickly.
- Bring the new mulch to the space you’re covering. Depending on your material, this could mean carrying a bag, moving a wheelbarrow full, or bringing a 5-gallon pail full.
- Using your hands or a shovel, place small heaps of mulch on the soil surface within the space.
- Using gloved hands or a rake, smooth out the small mulch mounds to a desired depth of 1 to 4 inches.
- Repeat as needed until you’ve mulched all the areas you want.
- After you are finished, water the area lightly to help the mulch settle and hold it into place.
The benefits of using mulch
- Covering the soil with mulch helps to shade plant roots on hot days. The mulch acts as an insulating layer, keeping the soil from getting as warm as it would when exposed, and helps maintain root growth. When soil temperatures get too warm, root growth slows or halts.
- Mulch helps prevent soil moisture from evaporating on sunny or windy days.
- Slows weed germination by blocking sunlight (some weed seeds need sun to germinate) or emergence.
- Insulates roots in winter, minimizing winterkill and helping prevent frost heaving.
- Improves the soil as it decomposes, adding organic matter and nutrients.
- Encourages beneficial soil organisms. Mulch provides a source of food for soil fungi and bacteria.
- Provides a barrier, keeping edible crops from coming into contact with the soil. When fruits and vegetables don’t contact the soil, they’re less likely to rot.
- According to the University of New Hampshire Extension, mulch also keeps fruit clean during heavy rainfalls. It absorbs the rain drops instead of having them contact the ground, collect dirt, and splash back up onto the fruit.
- Provides a tidy appearance to your landscape. Covering the bare soil with mulch helps make the space look finished and well-manicured.
The best time to mulch
Realistically, you can mulch whenever you can get out and do the project. Because, let’s face it, sometimes your schedule gets a little crazy, and you get to projects when life allows. However, there are two times of the year when it’s optimal for spreading mulch: spring and fall.
Mulching in mid- to late spring helps prevent weed seeds from germinating—some need sunlight to germinate, and mulch keeps them in the dark. Seasonal rains can also help break down organic materials and push nutrients into the soil. Plus, spring mulching gives your yard a fresh, clean aesthetic throughout the spring and summer.
Mulching in late fall protects plants as they head into winter, moderating the freeze-thaw cycles in the soil by providing extra insulation. This insulation helps reduce cold stress on the roots and prevents frost heave in cold areas, reducing winterkill and keeping plants from being pushed up out of the ground.
No matter which season you choose to mulch, plant on doing it when the ground is thawed and moist. Ideally, choose a day following a solid rain that soaks the soil.
Mulching tips & tricks
- Err, on the side of caution, buy an extra bag or two more than what you calculate you need. I always find someplace to put it, and it saves you a trip back to the store if your calculations are short.
- Spread mulch about 2 to 3 inches thick. A thinner layer is not deep enough to provide adequate benefits; a thicker layer doesn’t have good air circulation and can harbor pests. A thicker layer is also wasteful and unnecessary.
- Mulch a ring around your trees and shrubs. Keeping the grass 6 inches or so away from them is a fantastic way to prevent injury from landscaping equipment like mowers and trimmers. Just be sure you don’t mulch right against the trunk like a volcano—keep mulch 1 or 2 inches from the base.
- Wear gardening gloves to avoid getting little splinters if you’re working with bark chips.
- If you need a large quantity of mulch, buy it in bulk by the cubic yard. Many nurseries and big box stores sell mulch by the truckload for bigger projects, usually at a slightly reduced price per cubic yard. Plus, bulk quantities can be delivered to your home.
- How often you mulch depends on many factors.
FAQs about how to mulch
Which mulch won’t wash away with rain?
Using rock or stones is the best mulch for areas that get a lot of rain or see runoff from downspouts. The heavier the mulch, the less likely it is to be washed away by moving water. If you are set on having organic mulch, then opt for heavier wood chips or bark pieces.
Or, you can use a combination of materials. I mulch with rocks right where the downspouts drain and surround it with lighter, organic mulch.
Do you remove old mulch?
If you’re using organic mulch that breaks down, there isn’t any need to get rid of it every year. Removing it adds extra work to your to-do list and increases the amount of new mulch you need to purchase. I just mulch right over the older stuff to bring the mulch depth to where I want it.
Which mulch repels insects best?
Bark mulch like cedar or cypress chips contains natural volatile oils that repel bugs, so they are a great choice in areas where you’d like to keep insects at bay. They can be a useful tool in gardens or around your prized roses — places where insect damage poses a higher threat to blooms or vegetables.
Need help with your mulching project?
It’s no secret that landscaping projects, especially mulching, can take significant time and effort. With the help of LawnLove, you can have a gorgeous-looking yard without breaking a sweat or losing your weekends.
Reach out to us, and we’ll connect you with a local landscaping professional who will mulch your yard and have it looking beautiful in no time!
Sources
Main Image Credit: Tom Britt | Flickr | CC BY 2.0
