Maple trees are popular in the US. Their bonsai display, large leaves, incredible fall colors, and sweet syrup make them one of the most functional and attractive trees. Like other trees, maple trees shed many leaves in the fall, which you can use to mulch your garden.
Maple leaves are good for your garden because they are rich in nutrients and have a good carbon-to-nitrogen ratio. Unfortunately, maple leaves mat down if you don’t shred them first, thus blocking air and water from reaching the soil. Fallen leaves also retain fungus, which can ruin your garden.
The rest of this article will analyze maple leaves and how you should prepare and use them in your compost or mulch. I’ll also discuss what you can do to make maple leaves work best in your garden.
Are Maple Leaves Good for Compost?
One way to use fallen leaves in your garden is to compost them. If you spend a lot of money buying compost every growing season, you can take advantage of the fall season to collect tons of leaves for your compost.
Maple leaves are good for compost because they have a high calcium-to-nitrogen ratio. The C:N ratio in maple leaves is close to 40:1, while the ideal C:N ratio for compost is 30:1. This makes maple leaves closest to the optimal compost C:N ratio, so the leaves break down faster when composted.
As the materials in the compost decompose, the C:N ratio drops to 15:1 or 10:1. Maple leaves get to this ratio much faster than oak leaves, which have a C:N ratio of 60:1.
Composting Materials and C:N Ratios
When collecting leaves for your garden, you can choose compost them them or use them as mulch. Carbon and nitrogen ratios are important because they determine how fast microbial decomposition occurs.
Carbon is the building block that makes up about 50% of microbial cells. It is also a source of energy necessary for decomposition.
On the other hand, nitrogen is a component of enzymes, amino acids, nucleic acids, and coenzymes. It is essential for cell functions and growth.
The ideal C:N ratio is 30:1, meaning 0.07 pounds (30g) of carbon for every gram of nitrogen.
When the C:N ratio is lower, the excess nitrogen will be released as ammonia gas. Your compost will also emit undesirable odors.
Conversely, when the carbon parts are too high, nitrogen levels will be insufficient to support the growth and functions of microbial populations. The compost will not heat up as required so the decomposition process will be slower.
Green and moist materials usually have high nitrogen levels, while brown and dry materials are carbon-rich.
| High Carbon Compost Material | Estimated C:N Ratio |
| Maple leaves | 40:1 |
| Oak leaves | 60:1 |
| Pine needles | 80:1 |
| Sawdust | 325:1 |
| Wood chips | 400:1 |
| Straw | 75:1 |
| Shredded newspapers | 175:1 |
| Corrugated cardboard | 560:1 |
| High Nitrogen Compost Material | Estimated C:N Ratio |
| Coffee Grounds | 20:1 |
| Vegetable scraps | 15:1 |
| Clover | 23:1 |
| Alfafa | 12:1 |
| Grass clippings | 20:1 |
| Manure | 15:1 |
| Hay | 25:1 |
Maple leaves decompose faster than oak leaves and pine needles. If your compost materials have a high carbon-to-nitrogen ratio, you need to add green materials to introduce more nitrogen. For green materials with high nitrogen, you need to add more brown and dry materials (more carbon).
Pros and Cons of Using Maple as Mulch
Before using maple leaves as composting material or mulch, I recommend going through the list of advantages and disadvantages below:
Pros: More Nutrients, Better Soil Quality and Texture
There are over 100 maple tree species. Sugar maple, red maple, silver maple, and bigleaf maple are some of the most popular in the US.
At maturity, maple trees grow to a height of 164 – 426.5 feet (50 – 130 meters), depending on the variety. The crown spread is typically 25 – 30 feet (7.62 – 9.14 meters).
During fall, maple trees shed so many leaves.
Instead of disposing of them, you can use them in your garden to get the following benefits:
High Mineral Levels
Maple tree leaves contain at least twice the minerals available in manure. For example, 5% of the sugar maple leaf’s weight is calcium, magnesium, phosphorus, nitrogen, and other trace elements. The mineral content is twice that of the common pine needles.
Soil Enrichment
Maple leaves are deep-rooted, and most of the minerals absorbed go to the leaves. So, when you use maple leaves in your garden, the nutrients will enrich the soil.
Humus-Building Qualities
Maple leaves also have humus-building qualities that improve the soil structure of different soil types. For example, leaves improve aeration in clay soil. They also help sandy soils to retain moisture.
Feeding on Microbes
Leaves feed the microbes in the ground, absorb water and reduce runoff. They also contain large quantities of fibrous organic matter.
Low Lignin
Maple is one of the trees with leaves rich in calcium and nitrogen and low in lignin. These leaves decompose in a few weeks, unlike others like oak and sweet chestnut, which are rich in lignin but have low concentrations of nitrogen and calcium. Such leaves take ages to decompose.
Cons: Poor Water Absorption and Fungal Diseases
As mentioned, maple, like other trees, shed leaves in the fall and you can use these leaves in your garden as mulch or compost.
However, maple leaves carry some risks that you need to be aware of:
A Large Surface Area
The different maple tree species have unique features, often told apart by the leaf designs. All maple leaves have five finger-like projections. However, some leaves are slightly slender, while others are wide in the middle, like the Norway Maple.
The average width of the maple leaf is 3 – 6 inches (7.62 – 15.24 cm). In their natural state, these leaves take a long time to decompose.
When used as mulch, they will stick to the ground, doing more harm than good, such as blocking water from penetrating the soil and having no impact on the soil structure. As such, maple leaves will only be helpful to your garden when shredded.
Susceptibility to Fungal Diseases
Besides their physical limitations, maple leaves are also susceptible to fungi such as Maple Tar Spot, a fungus that attacks maple trees. Signs of this disease include dark, round spots on leaves. At a glance, you would think tar splashed on the leaves.
Maple Tar Spot is not fatal when treated early. Unfortunately, if the fallen leaves contain fungus, you may transfer the disease to your garden if you use the leaves as mulch or compost. The fungus remains in the leaves, and if you use them to mulch your garden in winter, the moisture will encourage the fungus to multiply.
To avert this problem, ensure you inspect the leaves for signs of Maple Tar Spot before using them. If you see tar-like spots, put the leaves in garbage bags and dispose of them.
All maple trees are susceptible to Maple Spot Tar, but it is most common in Norway, silver, and red maple trees.
Shred the Leaves and Store for Future Use
Fallen maple leaves can be unsightly, especially if you don’t know what to do with the tons of leaves that keep falling. Stuffing them into garbage bags doesn’t seem right, especially if you can use them to enrich the soil in your garden.
You can use maple leaves in multiple ways. However, you need to ensure you shred them first. This will reduce their size, and you’ll have an easier time putting the shredded leaves to use. They will also decompose faster during winter.
As noted earlier, maple leaves are large and don’t break down quickly when left whole. If you put them in your garden as they are, you may find them wet but barely decomposed in spring.
Here are the different ways to use maple leaves in your garden:
Add Them to Your Compost Pile
The carbon-to-nitrogen ratio in maple leaves allows them to decompose quickly. Keep turning the compost, and your compost will be ready for use in spring.
Use Them as Organic Mulch
Use the leaves as organic mulch to protect the plants in your garden during winter. Add a 2 – 3 inch (5.08 – 7.62 cm) layer of shredded maple leaves as mulch.
The mulch will protect the soil and plant roots from frost during winter. However, ensure the leaves do not touch the stems of the plants because they can introduce fungal diseases and stem rot due to high moisture retention.
Make Leaf Mold
Leaf mold is excellent for improving soil structure and fertility. To make it, layer shredded leaves, followed by garden soil or compost. Leave this pile untouched for a year, and then add it to your garden.
Store Them for Use in Spring
In fall, the leaves may be in abundance, but you will not have any dry leaves in spring. If you collect the leaves, you will have plenty of nitrogen-rich green material when you start weeding and pruning your garden. The shredded leaves will add the needed carbon to make compost.
The below video is a guide on how to make leaf mold for your garden:
Conclusion
Maple leaves have a fantastic carbon-to-nitrogen balance, so they decompose quickly. This makes the leaves an ideal choice for your garden mulch and compost. However, you need to confirm that the leaves are not carrying fungus before you shred and use them.
