Using Leaves in Garden Soil: The Pros and Cons


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Leaves can be found lying around any garden space and in some cases, become somewhat of a nuisance. However, these leaves when incorporated into the soil can have many benefits which would result in healthier plants.

Mixing leaves in garden soil can add nutrients to the soil by increasing the organic matter but at the same time reduce the vital nitrogen which the plant uses. During the decomposition of leaves, microorganisms use nitrogen within the soil which becomes temporarily unavailable to plants. Adding small amounts at a time will be beneficial.

It is recommended larger quantity of leaves be composted separately to produce nutrient-rich compost which can then be added to the garden to prevent any negative effects to the plant.

This article includes the ways you can utilize dead leaves and explains the pros and cons of adding them to garden soil as well as –

  1. How it should be added to Garden soil
  2. How long will the leaves take to decay
  3. The benefits of using dead leaves as mulch
ProsCons
Adds nutrients to the soilIt creates a temporary drop in nitrogen available for the plant
Increases soil aerationCauses yellowing of the plant leaves as a ripple effect
Helps with soil drainageCan cause stunted growth due to low nitrogen levels
Increases microbial activity within the soilLarge amounts will decay over time causing the soil to drop or sink

Benefits of Putting Dead Leaves in Garden Soil

The same situation is with fallen dead leaves. Dead and decaying leaves are very useful for the plant’s growth and soil fertility. 

Nature doesn’t produce waste but instead reuses everything in a repeating organic cycle. 

The benefits of incorporating dead leaves into garden soil are 

It Provides Food for Microorganisms

Dead leaves are thought to be very good food and shelter for the microorganism in open soil. Similarly, it is very beneficial for garden plants. 

Dead leaves provide an environment that facilitates the microorganism and enhances their growth within the soil. 

They enhance the humidity, lower the soil temperature and provide nutrients thus make an ideal environment for the microorganisms. 

These microorganisms absorb the nutrients (which plants can’t take up) and convert them into nutrients that are absorbed by plants. 

As a result, they make the soil fertile organically.

Provides Nutrients for Garden Plants

Dead leaves are a natural and organic source of nutrients. These leaves contain nutrients like nitrogen, phosphorus, potassium, and trace elements. 

The dead leaves are also a rich source of carbon compounds. These are the amazing organic fertilizer of your soil. 

They are maybe a little acidic but this depends on the nature of leaves you collect.

Helps with Soil Aeration

The dead leaves improve the soil structure in such a way that they scatter and merge between the dense particles of clay soil. 

As a result, they create gaps that trap air and allow soil aeration. 

This nutrient-rich soil also invites microorganisms that enhance soil aeration by their movements.

Helps with Soil Drainage

Leaves are a cheap, organic soil amendment that creates gaps that allow air to pass through the soil into the roots. Similarly, they provide spaces for water and nutrients. 

As they are mixed between the dense particles of the soil, they provide empty spaces for water to be absorbed and also drain excess water out of the soil.

They can also convert heavy soil into lighter soil which has the ability of excellent drainage.

The Side Effects of Mixing Dead Leaves into Soil

Nitrogen Deficiency

Mixing dead leaves into soil can create a nitrogen deficient environment for a short period of time. 

This is because microorganisms use nitrogen to break down the leaves into nutrients for the plant to use. 

Nitrogen deficiency in plants can occur when organic matter with high carbon content, such as sawdust, is added to soil. Soil organisms use any nitrogen to break down carbon sources, making Nitrogen unavailable to plants. [Source]

As a result, a nitrogen deficiency can be created. 

A shortage of nitrogen results in a marked decrease in plant photosynthesis and nitrogen allocation to the leaves in many plants.

Reduced nitrogen will therefore lead to pale yellow-green color leaves and also slow or stunted growth of the plant.

Drop in Soil Level

When large amounts of leaves are mixed into the soil it can cause the soil to become rich in organic matter that decays over time. 

As the decay continues, the soil level will drop over time. 

This can be alarming especially in raised beds where the entire shape and level will change due to the decomposition of the leaves. 

As a result, the soil will have added to supplement the drop in level.  

How to Add Dead Leaves to Garden Soil

1. Remove Dying Leaves from the plant

Prune your plants and remove the dead, weak, and diseased leaves. 

The pruning also helps in the healthy growth of plants as energy is utilized in the growth of younger and healthy leaves rather than decaying the dead and weak leaves. 

Now discard the diseased leaves and keep the dead and weak leaves.

2. Gather dead leaves

Gather all the dead leaves from your garden and on your roofs. The best leaves which make the excellent leaf mold are oak, peach, or leaves of the deciduous trees. 

Avoid the thicker leaves like host chestnut, sweet chestnut, rubber plant, or tough evergreen leaves because they require a too long time in the breakdown. 

You can collect pine tree needles but it makes acidic soil mulch which is suitable for ericaceous plants like blueberry. 

Never add leaves like walnut, eucalyptus, camphor laurel, cherry laurel, and leaves on the side of roads. If these forbidden leaves are added to the soil they will inhibit the growth of plants.

3. Crush or cut leaves up into small pieces

Crush the collected leaves into smaller pieces as a result they have more surface area for decomposition. 

They also mix up easily with soil. The crushing process will speed up the process of making leaf molds for your pots.

4. Mix thoroughly into some garden soil then add to the soil

Leaves should be mixed in approximately 2 to 3 inches within the soil to ensure that the leaves are properly covered and the microbes have full access to break start the decomposition process.

Garden Soil Recipe:

For the preparation of garden soil mixture:

Add 2 parts of leaves mold into 2 parts of sand/perlite and 1 part of compost with a little amount of some slow-feeding nutrients. 

Mix it well so that all the content is balanced equally. This is the best soil mixture for your grown plants.

Seeding Soil Recipe:

To prepare the seeding soil mixture the material changes because these are for the new ones. Like if you add fertilizers to a delicate seedling pot they will Burn. 

So add 2 parts of soil into 2 parts of leaves molds, 2 parts of sand, and a small amount of vermicast. Add a little amount of chalk if you feel that your soil is more acidic.

It is recommended that the soil be left for about two weeks for the decomposition process to be well on the way so that the seedling will not be affected by any nitrogen robbing.

Dead leaves in compost bin

How Long does it take for Leaves to Decay?

It takes almost 10-12 months for leaves to fully decay and form nutritious.

You can speed the process to 8-10 months by following the given steps.

  • Use a leaves mower and crush the leaves into smaller pieces.
  • Add a small amount of manure or other organic fertilizer.
  • Moist it continuously throughout the process.
  • Turn the pile upside down every month.

Is it Better to Compost the Leaves Separately Before Adding it to the Garden?

It is best to compost the leaves and convert them into nutrient-rich soil before mixing them into plant soil. 

The raw leaves are also good if used in small quantities or used as mulch. But if you have a large number of leaves then it is best to add them to compost and convert it into nutrient-rich soil. 

If you put a large part of leaves as mulch in the pot they will use nitrogen to decompose. As a result nitrogen deficiency will pop up in your plant and soil as previously explained.

The best is to use these leaves smartly and convert them into compost and use a little for mulch.

The best leaves for composting are those lower in lignin and higher in calcium and nitrogen. These include ash, maple, fruit tree leaves, poplar, and willow.

Lignin enhances plant cell wall rigidity, hydrophobic properties and promotes minerals transport through the vascular bundles in plants.

The worst leaves for composting are those higher in lignin and lower in nitrogen and calcium. These include beech, oak, holly, and sweet chestnut.

Higher lignin causes the leaves to be more rigid and also takes a long time to decompose.

Pro tip: Increasing the surface area of the leaves by breaking them up into smaller pieces will help them to also decompose faster as opposed to just throwing the leaves into a compost pile.

Can you Use Dead Leaves as Mulch?

Different types of mulches can be used as mulch such as wood chips, rubber chips, crushed leaves, or even decorative stones.

Among all these, dead leaves can provide much more value to the soil as a mulch substrate as it will protect the soil and organically provide nutrients for your plant.

They will not heat the soil like other mulches. They provide an amazing environment for the growth of beneficial microorganisms.

Using Leaf Compost in the Garden

Using leaf compost in the garden will help organically boost the nutrient content of the soil producing healthier crops and produce.

Leaf compost is similar to topsoil which has a darkened color signifying the quantity and quality of nutrients contained within the leaf compost.

Leaf compost will continue to decompose even when mixed with garden or potting soil cause the soil level to drop as time passes.

Using Green leaves in the garden

Mixing green Leaves into Garden Soil

Mixing green leaves into soil will also have the same benefits as dead or brown leaves. 

The difference is that the green leaves will take longer to decompose into soil. 

Green leaves will also tend to be more rigid in the soil giving it a more fluffy feel. 

Additionally, the soil drop or sink will be even more pronounced than dried or dead leaves. 

As recommended with dry leaves, composting will bring greater benefits than just mixing the leaves into bear soil. 

Mulching with Green leaves

Mulching with green leaves can be done and will bring all the benefits of using regular mulch but in addition can also bring pests, fungus, and other diseases currently present in those leaves.

Greener leaves should be places aside to start dying off and turn brown before it is used as a mulch. 

In addition, this gives enough time for whatever pests and diseases present to leave or die off.

Mixing Leaf Mulch into Soil vs Mixing Wood Mulch into Soil

Leaf MulchWood Mulch
Decomposes fasterTakes longer to decompose
Greater effect on Nitrogen availabilityLesser effect on Nitrogen availability
Easier to obtainSome work has to be done
Free and readily availableNot readily available 

See our detailed article on mixing old mulch into soil.

The Takeaway

The dead leaves when mixed into soil will provide plants with nutrients and oxygen. 

Additionally, dead leaves can aerate as well as promote drainage within the soil. 

However, during the process of decomposition, a nitrogen deficient environment can be created which can rob the plant of much-needed nitrogen which can lead to deficiencies and care must be taken when adding dead leaves to garden soil.

Although dead leaves can provide plants with beneficial nutrients it is often recommended that leaves firstly be composted externally and then added to garden soil to get the full benefit of the nutrients they possess.

JayLea

JayLea has a passion for plants and has been gardening since 2015. He has valuable knowledge about gardening and houseplant care and can answer everyday practical questions that every plant owner has.

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