Autumn usually signals a massive coordinated raking effort. All over your neighborhood, you’ll see people raking their lawns and bagging up massive amounts of fall leaves by the road. The irony is that they are exporting an all-in-one mulch, fertilizer, and compost out of the garden, only to purchase these inputs again in the spring.
If you want a free source of nutrients and weed-smothering mulch, here are 9 reasons to leave the leaves in your landscape!
Should I Leave the Leaves in My Garden?
Leaves one of the most valuable and underrated garden resources. If you want free mulch, fertilizer, compost, and soil conditioner, don’t let your leaves leave your property! Whether they stay at the base of your trees, hang out in garden pathways, or get spread around your vegetable beds, fallen leaves are worth keeping around.
9 Reasons You Should Keep Leaves in Your Yard
Leaving the leaves in your yard or garden may seem counterintuitive if you’ve been diligently raking them up for years. However, this fallen tree foliage is actually a golden resource for any gardener. Here’s why:
Leaf mulch, derived from fallen tree leaves, is a top-notch choice for mulching various plants while inhibiting weed growth.
Leaf mulch is arguably the best mulch you can use for fruits, vegetables, flowers, and landscape trees or shrubs. This tree-powered amendment nurtures the soil while preventing weeds from competing with your crops.
Have you ever noticed how a dense oak grove or old-growth fruit orchard seems to have very few weeds on the ground? It’s because trees have a built-in mulching system. When they drop their foliage in the autumn, the leaves naturally smother any potential competitor plants at their base. The thicker the mulch layer, the more weed-suppressing action it has.
However, if your leaves fall directly on your lawn, you probably don’t want them to kill your grass. Raking and wheelbarrowing them to your ornamental or vegetable garden beds is a great solution. They will keep weeds at bay and nurture the soil simultaneously.
Species to Avoid
The only leaves I would avoid spreading in a vegetable garden are those with allelopathic properties, such as:
- Black walnut
- Oak (if not rotted or composted)
Allelopathic means the trees produce compounds that suppress the growth of other plant species. For example, black walnut leaves are full of juglone, which acts as a natural herbicide that will harm your other plants. Similarly, oaks have high amounts of tannins and lignin, making them slow to break down and potentially allelopathic to some plant species.
These leaves are best left at the base of their respective trees or used only in pathways between other beds. You can also slowly compost these leaves, but be forewarned, it takes quite a while for the allelopathic compounds to break down, with some studies showing it may take up to a year.
Most every other landscape tree is perfectly safe for your veggie or flower garden. If you hate weeding, you don’t want to miss out on nature’s built-in weed prevention tool!
Improve Soil Organic Matter
Leaf decomposition by microorganisms enriches your soil, enhancing its structure and fertility.
As microorganisms decompose leaves, they become a valuable source of organic matter. This process enriches your soil, improving the structure and adding fertility. Leaf mold is a magnet for beneficial fungi and bacteria. The longer you let leaf litter decay, the more benefits it adds to the soil.
Soil organic matter is the secret sauce to the healthiest garden possible. It improves just about everything, including:
- Soil texture (more loamy and rich!)
- Mineral content (more nutrient-dense food!)
- Microbial diversity (mycorrhizal fungi can improve plant immunity and drought resilience!)
- Water infiltration (no puddling!)
- Water retention (less irrigation!)
- Plant-available nutrients (less fertilizer!)
- Carbon sequestration (fight climate change!)
- More worms (free soil-building and aeration!)
- Less compaction (roots can go deeper!)
No matter where you leave your leaves in the yard, you improve your garden and the ecosystem by letting them rot into the soil. If you’re wondering how the leaves get to the lower soil layers, rest assured that worms and microorganisms will do all that work for you.
Pro Tip: If you want to use leaves to enrich your vegetable beds, a lawnmower is one of the best tools for the job. Use a high-lift mulching blade and run the mower over a layer of fallen leaves in your yard. Allow the large grass bag to collect the shredded leaves, then simply carry that bag to the garden and dump it on your beds! No rake needed!
Rich in Nutrients
Leaves contribute up to 80% of forest nutrients, making them excellent natural fertilizers for gardens.
Trees spend an entire season growing a huge canopy of leaves, so you can only imagine how many nutrients are stored there! They are a significant source of the most important plant nutrients, including:
Leaf litter is rich in carbon, the most vital building block for soil organic matter. When trees suck carbon dioxide out of the atmosphere, they store some of that carbon in their foliage.
Known as the most common fertilizer, nitrogen is essential for leafy foliage growth and overall plant vigor. Although leaf mold isn’t particularly rich in nitrogen, microbial breakdown still contributes to enriched soil nitrogen. However, leguminous trees like locusts, acacias, and eastern redbuds can have a much greater proportion of nitrogen in their canopies.
This is the most crucial nutrient for flower production, fruiting, and root development. Fallen leaves release phosphorus as they decompose.
Potassium aids in a plant’s response to stress. It can improve disease resistance and fruit quality. Autumn tree leaves can completely replace potassium fertilizers if applied in sufficient quantities.
Tree leaves are very high in calcium, which is responsible for helping plants build strong cell walls. Problems like blossom end rot can occur when calcium is deficient, so leaf mulch is a nice addition to tomato beds.
Unsurprisingly, scientists have found fallen leaves responsible for up to 80% of the nutrients that forests use to grow! If those little fluttering multivitamins can grow entire forests, there is no doubt they will help your garden. After all, no one is out there adding fertilizer to a forest.
If you want to reduce fertilizer costs and build a healthy soil ecosystem with built-in nutrient cycling, let the leaves decompose naturally on the soil surface! Alternatively, add them to your vermicompost bin or outdoor compost pile to speed up decomposition.
Insulate Plant Roots
Leaves act as protective insulation for plant roots during frost and create a cooler root zone during hot summers.
Leaves are like an insulating blanket, protecting plant roots and crowns from frost damage. Young trees, tender perennials, and overwintering vegetables can all benefit from a thick layer of leaves around their base.
At the same time, leaf mulch can provide the opposite effect during hot summer weather. By blocking the sun’s harsh UV rays from hitting the soil surface, they buffer the rising ambient temperatures to create a cooler microclimate at the base of your crops. I like adding leaf mulch around my summer lettuce to keep the root zone cool and prevent bolting.
Just be sure you don’t press the mulch too close to the base of the plant, as this can lead to stem rot.
Amazing Compost Input
Creating your compost is cost-effective and simple with the right ingredients and aeration.
Instead of hauling in straw or bark as carbon-rich “browns” in your compost pile, use the leaves you already have on hand! Aged leaf mold is one of the best compost inputs to balance out large volumes of nitrogen-rich “green” material like grass clippings, manure, or veggie scraps. Even if it’s not already aged down, brown fall leaves are an incredible carbon-rich additive for the compost pile.
Compost is one of the most important and most expensive garden amendments. With a simple DIY bin and the proper ratio of ingredients, you can make your own compost with fallen leaves. Generally, a ratio of 30:1 (browns to greens) creates the most optimal conditions for decomposition. For example, 30 scoops of leaves are needed to balance out 1 scoop of chicken manure. Don’t forget to aerate the pile when it gets steamy.
Optionally, run your lawn mower over a thin strip of leaves before adding them to the pile. The mower will shred them into fine pieces that break down quickly. A mulching blade is the best tool for the job. Shredding the leaves reduces the overall surface area, making them break down faster in place or in a compost pile. Chipped leaves also work excellently as worm bedding in a vermicompost bin.
Improve Soil Moisture Retention
Leaves act like a natural sponge, enhancing soil moisture retention.
If you feel like you’re constantly irrigating your garden, yet the soil is still dry, or your crops are regularly wilting, leaves can help with that, too! Leaf litter is like a natural sponge that soaks up water and holds it in place. Whether you mix leaf waste into the soil or use it as mulch, it will significantly improve soil moisture retention so you can go longer periods between waterings.
As leaves break down, they release humic substances that improve soil water-holding capacity. Humic compounds bind the soil particles together, making it more sponge-like. This leads to improved soil aggregation, which clumps soil together for greater pore space. Imagine non-aggregated soil like a bunch of marbles stacked together. The air space between them would be quite small.
Once humic acids accumulate in the soil, the aggregates become like bowling balls, with large pores in between them. Water can hang out in those open spaces so plant roots can reach them even during the driest periods.
The only caveat here is for waterlogged soils. Avoid adding dense layers of leaf litter over compacted or soggy soils because it will prevent them from drying out. The lack of airflow underneath the leaf layer can lead to issues like root rot or pathogenic fungal growth.
Leaves help prevent muddy, slippery pathways.
Spreading leaves in garden pathways can prevent walkways from becoming muddy and slippery during the winter. When you’re running out to the garden for a quick sprig of rosemary or a few leaves of overwintered kale, you won’t have to worry about tracking muddy boots back into the house!
Another benefit of pathway leaves is their water management. If your region receives heavy rain, the leaf layer can help soak it up, preventing flooding between your raised beds. This is ecologically beneficial because it prevents soil or fertilizer from washing away into nearby waterways. The leaves act like a weighted anchor, covering everything beneath them just like nature prefers.
Prevent Waste from Going to the Landfill
Roughly one-third of landfill waste is compostable organic material.
An estimated one-third of landfill waste is actually made of compostable organic materials! One study from California found that 9% of biodegradable waste in landfills could have been composted in a yard waste facility (or in residential gardens!) It may not sound like much, but that amounts to millions of pounds of organic materials!
It’s a shame to imagine nature’s rich resources ending in an anaerobic landfill. But this often happens when people set bags of leaves by the road! If your city doesn’t have a yard waste composting program, the perfectly biodegradable leaves could be treated like trash.
It is far more environmentally friendly to keep leaves on your property and divert organic waste away from landfills. You’re also potentially saving extra fossil fuel emissions from the trucks that would have to transport away your leaf bags. Save yourself some effort and protect the earth at the same time!
Less Back-Breaking Work!
Rather than the labor-intensive task of raking and bagging leaves, allow them to decompose on your lawn or in the garden.
Raking and bagging leaves is ridiculously time-consuming and physically demanding. Instead of straining your back, let those leaves rot in place or transport them a short way to your garden. If you still need to get leaves off your grass, consider raking them into nearby ornamental beds for a nice, aesthetically pleasing mulch.
One man’s trash is another man’s treasure! Embrace the natural cycle of leaf decomposition that can turn autumn waste into free fertilizer, mulch, and compost. Whether you let them rot at the base of your trees, spread them around your pathway, or use them to nourish your vegetable beds, you do not want to miss out on this free resource.
Next time you rake up fallen leaves, consider letting them stay in the garden to work their magic. Your garden and the planet will surely thank you!