Leaf Mulch: Tree-Powered Garden Additive

You’ve heard of wood chip mulch and straw mulch, but did you know that leaf mulch is just as good? In some situations, it may even be better to use leaf mulch instead of wood mulch. Not only do leaves suppress weeds, but they’re also a great organic material that is free. 

So if organic mulch is something you’re thinking about as we head toward winter, consider leaf mulch for building and maintaining healthy soil. Organic mulches come in many different varieties, but leaf mulches are one of the best resources to have on hand. 

Incorporating leaf mulch into your landscape will assist with plant growth and provide valuable nutrients to the ground of your vegetable garden or flower beds. It’s great for your compost bin too. Inorganic mulch might be the choice for some, but for most gardens leaves are more than appropriate.

So what are the intricacies of working with leaf mulch? Read on, and we’ll examine how you can use this organic material in your home garden.

What Is Leaf Mulch?

Put simply, leaf mulch is piles of leaves in various forms that act as a protectant to plants and the surrounding soil. Leaf mulch is organic matter that comes from a tree. Because trees tend to drop leaves annually (unless they’re evergreen), using leaf litter in the garden is a great way to pay nothing at all for mulch. 

Leaf Mold

Leaf mold is what makes leaf mulch so great. Do you ever wonder how the forest is so rich, or why the forest floor is so soft? This has everything to do with leaf mold. As leaves fall, they litter the forest floor and decompose into leaf mold. Leaf mold conditions the soil and helps the ground retain water, giving way for understory plants to grow when spring comes. 

Leaf mold also provides aeration to the soil and allows for easier movement of micronutrients and organisms that improve the quality of soil. Micro-organisms like fungi, protozoa, and nematodes give plants growing there greater protection from disease and pests. It also acts as a soil warmer, keeping living creatures alive through the tough winter times. 

Leaf mold is the reason so many people tout leaf mulch as the ultimate mulch. 

Types of Leaf Mulch

There is a lot to consider when using leaf mulch in your compost pile, flower beds, or vegetable garden. The type of leaf mulch you choose is important. Different leaves break down and serve different functions. Some are better suited for certain situations while others are best used elsewhere. Consider the following before applying mulch to your garden. 

Partially-composted leaf mulch comes from leaves that haven’t quite made it to leaf mold just yet. This could be on the forest floor, in vegetable gardens, or your compost. Shredded leaf mulch comes from fallen or green leaves which have been shredded via some human-guided mechanical process. These are whole dry leaves that come from dead limbs, or fallen leaves. 

There is a lot of debate as to whether partially decomposed leaf litter is a viable option as mulch. The truth is it is, even if it needs to break down further before use, how it is applied is the key. If you have a very hot compost pile, adding dry leaves can help. But adding green leaves will only exacerbate the problem. So think about your desired environment and adjust your mulch to fit that desire. 

Grass is a viable option for leaf mulching too. When applied in a thin layer, it provides the nitrogen-rich fertilizer mulching is known for. It’s even great to mix with leaves as mulch. You can always incorporate leaf mulch in with hardwood mulches too (where appropriate). 

A Word of Caution

Many gardeners say black walnut leaves are not suitable for vegetable beds because they contain natural herbicides that can inhibit plant growth. Juglone is one such compound that black walnut leaves contain. The same goes for grass clippings, as they have a bad reputation for robbing nitrogen from the soil. But both are good in thin layers, especially when they’ve been composted adequately. As time goes on, both provide valuable nutrients and improve soil structure. 

Poisonous plants like poison ivy, sumac, Virginia creeper, and stinging nettle can be used as mulch (just as you would wood mulch and other leaf mulches). Although all organic mulches decompose into beneficial nutrients, these plants do not lose their skin-irritating qualities over time. This could make using their shredded leaves dicey in the garden. You don’t want to find yourself digging only to come out with uncomfortable, persistent rashes. 

Oaks are also known for adding acidity to the soil through the tannins in their leaves. Green pine needles (not brown ones) and evergreens provide more. When you spread them, think about whether or not an area contains acid-loving plants. Nasturtiums, blueberries, daffodils, and hydrangeas are just a few plants that love evergreen mulch leaves. In neutral and alkaline soil-loving plant beds, wood chips may be a better option over evergreen leaves. 

Leaf Mulch Pros

Let’s talk about all the reasons to apply leaf mulch in your garden. First, it helps you regulate soil temperature. This becomes a huge issue in colder and hotter months. Soil temperatures that are regulated will keep more vulnerable plant roots safe in the dead of winter.

Leaves also draw in other beneficial organisms like worms, who help promote the microbiome in soil. This makes your yields more vigorous. Related to our first advantage, leaf mulch also helps retain soil moisture. So in the hot summer, leaf litter will help even sandy soils retain moisture, and sustain your plants through extremes.

Leaves suppress weed growth, allowing your plants to thrive without the threat of nutrient loss. Finally, they prevent soil erosion by reducing soil compaction that can occur in heavy soils. 

Leaf Mulch Cons

But leaves are not without their pitfalls. If your combo of grass clippings and shredded leaves isn’t placed properly, you’ll have organic matter strewn about your yard by the wind. You can also have the opposite problem with improper placement.

If you spread a too-thick layer of leaf litter in an area, it can create an impenetrable layer that can choke out smaller plants in your garden. This isn’t great for many plants that require good drainage. But if the leaves aren’t chopped up, they can also become matted together and prevent moisture from reaching the soil entirely, and that’s just as bad!

Leaf mulches decompose faster and require regular reapplication. This isn’t so bad, considering trees drop their fall leaves annually, but you may find the mulch doesn’t last until that time. Lastly, they could contain weed seeds that will circumvent the beneficial weed suppression dried leaves are known for.  

Leaf Mulch Uses

As we mentioned in the previous section, improper application of dried leaves over the soil is the root cause of the problems associated with leaf mulch in the garden. On that note, let’s discuss the ways you can use leaf mulch to reinforce the benefits mulching is known for.

Garden Beds

An annual application of fall leaves is the easiest way to use leaf mulch. This could be dried fallen leaves that you rake into your garden beds. A leaf blower also works to bring the leaves together. It could also be collected in plastic trash bags and then applied in an inch layer over the surface area of your garden. 

Whether you shred leaves or not is up to you, but note that shredding leaves will help quicken the decomposition process. Whole leaves are just as viable an option, but they’ll take longer to break down. You can employ a mulching mower with a bagging attachment, or a basic lawn mower. Fresh leaves and fresh grass clippings are ok, but they may be better for beds that are lying low in wait for spring planting. 

Compost Piles

Another great use for leaf mulch is in your compost pile. This could be shredded, fresh, or even whole dried leaves from either hardwood trees or softwood trees. Incorporate leaves, grass, and shredded bark in compost, along with kitchen scraps, and processed small trees and you’ll find you have a very viable source of nutrients for the gardening season. Pile dead leaves on your compost heap, and you’ll lock in moisture that is much needed for new plants. 

Just remember to use the right kind of leaves here. Green leaves will heat compost. Dried leaves will help balance out the heat, as they lack most of the nitrogen content of green leaves. 

Lawns

Speaking of moisture, dead fall leaves have proven time and again to be great for home lawns. The leaves lock in moisture that is so needed for water-drinking grasses. They bring in earthworms and organisms that keep the soil where your grass is planted healthy too. As long as you apply a thin enough layer, and avoid choking out the grass you’ll have an even more viable lawn in the following spring. Use your lawn mower to mulch them in place.

Wildlife Habitat

There’s a saying among ecologists: leave the leaves. Why? Because leaves protect insects, gastropods, and worms that need a warm moist place to live in the weather extremes. They shelter moths, butterflies, and beetles too. More insects in the area means more food for birds. That means more food for bigger birds, and for those that eat those big birds, too. Leaving the leaves is one of the best ways you can be ecologically friendly in your gardening practice, and you get the added benefit of leaf mulch along with that friendliness. 

However, there is no harm in leaving the leaves in organized locations. If you’d rather have your leaf mulch on the garden beds instead of on the lawn, that’s just fine, particularly if your HOA requires a maintained look. Mulching all the garden beds with leaves will provide ample habitat in your yard for overwintering insects.

How to Mulch With Leaves

We’ve talked about some of the conceptual uses of leaf mulch up to this point. Now let’s discuss the step-by-step methods of leaf mulching. 

Leave the Leaves

Just as we discussed in the last section, you can simply leave the dead leaves where they are and let them do their thing. Nature had a lot of time to figure out the best ways to fertilize the earth in winter. You may notice benefits to your garden in the form of natural pest control, and attracting beneficial pollinators. But some situations require a little more effort than the live and let live method.  

Gather and Relocate

You can rake leaves from the lawn directly into your garden, as we discussed earlier. Or you can run a lawnmower over the fallen leaves to break them up, and then move them into the desired space. The same goes for grass. Collect it as you mow, and apply it elsewhere, whether it’s a flower bed or compost bin. 

When you apply leaf mulch to your garden, be sure to keep the layer under three inches. Too much will have undesirable effects on any plants still growing. If you’re letting the bed stay fallow over the winter, mound up the leaves as high as you’d like, as they’ll decompose down into the soil!

One interesting use for leaf mulch is winter insulation. Many rose gardeners swear by pruning down, uprooting their rose plants in fall, and laying them on their side to be completely covered in leaves. The leaves provide adequate warmth, protection, and moisture to keep roses going through hard times. 

Green Mulch

Say you’re one of those people that likes to trim the bushes and trees in your yard. You can use green leaves from those endeavors to mulch your beds. Keep the layer you apply much thinner in areas where plants are growing because it will take longer for these leaves to break down over time. Feel free to shred them to catalyze the decomposition process, though.  

Frequently Asked Questions

Q: Are leaves a good mulch?

A: They are an excellent mulch in most situations because they are full of nutrients that create rich soil when they break down. 

Q: Is leaf mulch better than wood mulch?

A: It depends on the situation, but overall leaves break down faster than wood. They do all the same things wood mulch does too. 

Q: Can you use fresh leaves as mulch?

A: Yes. As long as they come from a disease-free source and you shred them first they’ll work as mulch.