Mulching your yard and garden is a common annual task, since wood chunks often decompose quite a bit over the course of a year. However, you might be wondering what is the best way to deal with existing mulch.
So, what should you do with old mulch? If the mulch has not decomposed, you can loosen it and turn it over to reuse it or add a thin layer to the top of it to refresh it. You can also move it to a new location. If the mulch has begun to decompose, you can mix it into the soil or add it to your compost pile to speed up decomposition.
Of course, when certain mulches (like sawdust) are mixed into soil, they tie up nitrogen as they decompose. This temporarily prevents plant growth, so be careful when mixing mulch into soil where you want plants to grow.
In this article, we’ll talk about what to do with old mulch. We’ll also answer some common questions about mixing mulch into soil and turning it into compost.
Let’s get started.
What To Do With Old Mulch
Having old mulch in your yard isn’t necessarily a problem. You have a few options when deciding what to do with it, including:
- Loosen or turn over the old mulch – this is probably the easiest method. It might be necessary if the old layer of mulch is “crusted”. Be careful not to put too much new mulch on top of the old layer!
- Mix old mulch into soil – this method takes a little more work than loosening. It is a good method if the mulch will compost in place without tying up too much nitrogen in the soil.
- Add old mulch to compost – this method takes the most work, since you must rake up all the mulch, shovel it into a wheelbarrow, and move it to your compost pile.
- Reuse old mulch elsewhere – this method also takes a lot of work, but if the mulch has not decomposed, you can move it to use elsewhere.
Loosen Or Turn Over Old Mulch
Loosening old mulch by turning it over or fluffing it up is one of the easiest ways to reuse mulch. When you turn old much over, the entire layer loosens.
This prevents the mulch from condensing into a hard layer, which can prevent water from getting into the soil below. A thick layer of mulch is more likely to become hydrophobic (meaning it repels water).
After loosening old mulch, you can add another new layer of mulch on top of it. Just remember that the total amount of mulch only needs to be 1 to 4 inches, depending on soil type and the size of the mulch chunks (see the table below for more detail).
& Soil Type
You can learn about what to avoid with mulch in this article.
If most of the old mulch has decomposed, you can sometimes mix it into the soil without harming plants (more on this later).
How Do I Turn Over Old Mulch?
To turn over old mulch, you can use a rock rake to loosen the pieces and move them around a bit. This will prevent the mulch from forming a hydrophobic layer.
Raking will also prepare for another thin layer of new mulch to refresh the old one. Be sure to rake lightly to avoid damaging any shallow plant roots that may be present in the mulch or in the soil just below the mulch.
For the same reason, avoid digging with a shovel, trowel, or other sharp tool. These can sever plant roots and damage any landscape fabric material that you have underneath the mulch.
Mix Old Mulch Into Soil
If the old mulch is partially decomposed or made of fine particles, you can just mix it into the soil. This will speed up decomposition of the mulch, adding both organic material and nutrients to the soil.
However, there are some cautions when it comes to mixing mulch into soil.
Is It OK To Mix Mulch Into Soil?
For most mulches, mixing them into the soil will speed up decomposition. This will add organic material (from rotted wood, etc.) and nutrients to the soil.
However, certain mulch types will temporarily tie up nitrogen in the soil as they decompose. One of the biggest culprits is sawdust.
Sawdust has lots of carbon, as does any type of wood mulch. However, the small particle size of sawdust means that it will decompose quickly.
As sawdust decomposes, the carbon in the wood ties up nitrogen in soil as it decomposes. This makes nitrogen unavailable for plants, stunting their growth or killing them.
According to the Texas A&M University Extension, this lack of nitrogen can last anywhere from several months to several years. The time frame depends on the amount of sawdust added to the soil and the soil conditions (including moisture and aeration.)
A better option is to use sawdust for:
- animal bedding (when mixed with the high nitrogen content in manure, it will decompose faster, and the mixture will make a good compost)
- covering ground between rows in a garden (this will smother weeds and prevent new ones from growing)
- compost (add plenty of grass clippings or other nitrogen-rich materials and water the pile to make it decompose faster)
There are lots of other alternatives to mulch and sawdust, including:
- Grass clippings
- Pine needles (pine straw)
You can learn more about other alternatives to wood mulch here.
Does Mulch Turn Into Topsoil?
Mulch does not turn into topsoil. Instead, mulch turns into compost as it decomposes over time (this compost, in turn, feeds the topsoil).
Remember that topsoil contains some compost (organic material and nutrients), but it also contains minerals, clay, and sand (from rocks affected by weather over a long time period).
You can learn about the difference between topsoil and mulch here.
Add Old Mulch To Compost
As mentioned earlier, you can turn old mulch into compost by adding it to your pile. This takes some work, since you must scrape up the mulch with a rake, shovel it into a wheelbarrow, and move it to the compost pile.
However, this lets you add a completely new layer of fresh mulch to your landscape. Before you add old mulch to compost, here is a quick checklist to look over:
- Is the mulch biodegradable? Gravel and rubber mulch take a long time to decompose, so they should not be added to a compost pile (you are better off reusing them for another garden project).
- Is the mulch clean? Some mulch is treated with dyes to give it a different color. Other mulch comes from trees that were treated with pesticides or herbicides that can hurt plants or bees. Either way, consider the source before you put wood mulch in a compost pile.
- Can you balance the compost pile? Adding too much carbon-rich material (like sawdust) without a balance of nitrogen-rich material (like grass clippings) will slow down or stop a compost pile from decomposing.
Should You Remove Old Mulch?
You do not need to remove old mulch before adding a new layer of mulch. As mentioned earlier, you can loosen it up with a rake to refresh it or mix it into the soil before adding a new layer.
However, if the existing layer of mulch is too thick and you want to add new mulch, you should remove some or all of the old layer.
Also, if your mulch is moldy, you may want to remove the old stuff before adding new clean mulch.
Does Old Mulch Make Good Compost?
Old mulch can make good compost, subject to the checklist mentioned above (mulch should be biodegradable, free from pesticides or herbicides, and balanced by nitrogen-rich materials in the compost pile).
Reuse Old Mulch Elsewhere
The last option is to reuse old mulch in another part of your yard. If wood mulch is not decomposed (or if you used rubber, gravel, etc.), you can recycle it.
Rubber or gravel mulch is your best bet in a location where you don’t want plants to grow (since these will not decompose to add nutrients and organic material to the soil below).
Wood mulch is your best bet in a location where you have some plants growing (since it will decompose to slowly feed the soil over time).
Should I Water Mulch After Putting It Down?
You should water mulch after putting it down. This serves two purposes:
- Helps the mulch to settle – that way, you can see if there are any thin spots and you can thicken them up a bit with more mulch.
- Prevents hydrophobic mulch – watering helps to prevent a hydrophobic layer of mulch that repels water (a hydrophobic layer of mulch prevents water from getting to the soil and plant roots below).
Now you know what to do with old mulch and how to repurpose it for other garden uses.
I hope you found this article helpful. If so, please share it with someone who can use the information.
You can learn about how to prevent mulch from washing away here.
You can learn about how cedar mulch compares to other types of wood mulch here.
You can find some of the best options for mulch in a vegetable garden here.
If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here. Enjoy!
What To Do With Old Mulch That Is Decomposed. Decomposed organic mulch can still be very useful as compost or a soil amendment, as long as it isn't dyed. In fact, when used properly, organic mulch acts as a fertilizer and is a beneficial supplement for your plants.Should you rake up old mulch? ›
Matted mulch can hinder rain and sunlight from soaking through and feeding the plant roots beneath the soil. To prevent mats, removal is not the answer. Instead, fluff the mulch using a rake or cultivator and then add more mulch to the top.What is the easiest way to remove old mulch? ›
If you need to get it out of the way, shovel the mulch into a wheelbarrow, dumping successive loads onto a tarp off to the side. Apply compost onto the vegetable garden bed or annual flower bed, and till it under or work it into the soil with a spade.Can you use old mulch for compost? ›
Old mulch can be put in your compost bin if made from organic material. However, the type of material used in the mulch will determine how long it will take to completely break down in the compost. For example, Woodier materials take longer to decompose than softer materials, such as straw.What is the white stuff under old mulch? ›
The white stuff is a beneficial fungus that is decaying the organic matter you put into the bed. These fungi, called saprophytic fungi, do not attack plants or cause plant diseases. They feed on dead organic matter, like mulch, compost, soil conditioner, etc. They are critical to soil health.Does old mulch turn into dirt? ›
All organic mulch breaks down and eventually turns into soil. Mulch will become ineffective at suppressing weeds as it becomes compost. Below the compost layer, is what used to be composted mulch, but is now soil. As mulch is topped up every year, the layers of mulch, to compost, to soil will keep building.Does mulch attract termites? ›
Mulch doesn't necessarily attract termites, but can serve as an invite for them to feast on your house.Does mulch go bad? ›
As long as it's dry, a sealed bag can sit indefinitely. Bagged mulch can go sour or moldy in wet areas, or even can attract pests, so proper storage is really all you need for a long-lasting product.What is the best tool to break up mulch? ›
Wheelbarrow – A perfect tool for hauling leaves, mulch, and brush with much less back work. Shovels – Shovels come in lots of shapes and sizes so it's best to think about what chores you would need a shovel for. Rounded shovels are good scoopers. Flat squared-off shovels are best for edging.How often should you remove old mulch? ›
Mulch should be replenished or replaced as you start to see signs of decomposition, soil erosion and discoloration. And you'll mostly likely need to remove and replace all mulch after 5-6 years.
To promote decomposition, mix leaves with grass clippings or other materials high in nitrogen. If possible, shred the leaves prior to composting. The smaller the size of the material, the faster it will decompose.How long does it take mulch to compost? ›
The composting process in the average pile takes about 6 to 8 months, though an ideally mixed and tended pile may take less than 8 weeks to become compost.Can you burn mulch in a fire pit? ›
It is not safe to have your fire pit around most mulch because it typically contains many flammable materials, which can be a fire hazard during long, dry seasons.What is the difference between mulch and compost? ›
Compost and mulch are terms often used synonymously. However, there is a big difference between the two and are not to be used the same way. Compost is biologically active material that breaks down from organic matter. Mulch, on the other hand, is any material, organic or inorganic, that covers a given soil surface.What are the white egg looking things in my mulch? ›
What they are likely to be are a common type of fungi called saprophytic fungi. That's not a pathogenic or harmful fungi. Those little white, fuzzy balls are likely just fungal hyphae and the fuzziness around the spheres are the roots of the hyphae.What is the brown stuff growing on my mulch? ›
Bird's nest fungi resemble tiny grey to brown bird's nests up to 1/4 inch in diameter with eggs. These fungi may grow in large areas of mulch, but they are not a problem. The "eggs" or structures of the fungus splash out of the nest when hit by a raindrop.What is the black stuff growing on my mulch? ›
The fungi and mold break down the mulch as a part of its natural process. These mold patches come in a variety of colors like brown, white, black, orange, and bright pink. It can certainly be an eyesore, but it's a natural part of plant life that you shouldn't worry too much about.Does old mulch attract bugs? ›
While organic mulches naturally decompose and are beneficial, they also attract insects looking for warmth, shelter, and food. Insects eat the pine bark mulch along with the bacteria and fungi harbored within its moist, dark confines. Pests that aren't true insects but are linked with infestations include spiders.What type of mulch does not decompose? ›
Unlike natural mulches, rubber mulch doesn't decompose, so it's "sustainable." It doesn't add any nasty organic matter to the soil the way bark and pine straw do. Rubber mulch keeps the soil surface cool by trapping all of the sun's heat atop it where your feet are.How long does it take mulch to turn into dirt? ›
The practical life-time of mulch can be anywhere from 4-7 years. This is how long it takes for a layer of mulch to completely break down, although it depends on a number of different environmental factors (e.g. in direct sunlight, covering very wet ground etc).
Wood mulches may attract American cockroaches, who like to feed on decaying wood. The best mulch for roach prevention is an inorganic mulch, such as rubber or gravel.Does mulch attract mice? ›
Types of Pests Attracted to Mulch
Typically, mulch can attract: Termites. Ants. Mice.
Any organic mulch, whether it's derived from leaves, grass clippings, compost, wheat straw, or peat moss, has the most tendency to attract bugs and unwanted pests.
While mulch is great, it also creates an ideal environment for pests like termites to congregate. The mulch shields them from the elements so that they can thrive. For this reason, it's not always the best idea to lay mulch right next to your home's foundation.Why should mulch not touch the trunk? ›
Keep mulch about 12 to 18 inches from the trunk for any size of tree. Mulch should not be piled against the trunk (above) because roots may grow there (below) and girdle the trunk.Can you use mulch that has mold? ›
It can be very unsettling to look at your flower beds and see fungal growth, but it's important to remember that mold in mulch is natural, is not harmful, and can be easily dealt with.Why does mulch harden? ›
During the summer, fresh woody mulches become hot from decomposition, which dries out the mulch. Fungi then colonize these dry, dusty mulches, making them thick and matted.How do you spread bagged mulch? ›
Spread mulch — Shovel mulch from your wheelbarrow or shake mulch from your bag into small piles. Then use your hands to spread the mulch, especially as you get close to the base of your plants. How deep should your mulch be? You should spread your mulch to be two to four inches thick.What plants do not like mulch? ›
It's especially important to avoid using rocks as mulch around common foundation plants like azalea, hydrangea, and yews; these plants thrive in acidic soil (soil with a pH level below seven).What is the best way to keep mulch from washing away? ›
To reduce the mulch from washing away, you can add perimeter plants. These perimeter plants include hostas, sweet woodruff, creeping thyme, and other short-border plants. These plants are suitable for keeping the mulch put because they create a physical barrier for the mulch during the growing season.
Since lava rocks are porous, they are much lighter than traditional stone, and this makes them ideal as mulch since they have the advantage of being able to retain water. Pumice stone is a favorite stone mulch for many landscape experts, for its water retention properties and its attractive dark gray color.Should I turn over my mulch? ›
Turn it Up
Every couple months you should be turning your mulch since the top layer will naturally compact with the soil. Mixing and turning mulch can help deter mold growth under the top layer, allow it to breathe and help water flow through more easily.
At most, you will need to replace your mulch once a year. If you want to know when to replace your mulch, the best thing you can do is to check the mulch at the beginning of spring and observe the condition. If it still looks much like it did when you laid it down, then it is probably good for another year.Should I remove mulch before winter? ›
To reduce the chances of crop damage from a late frost or freeze, leave the mulch on as long as possible. Removing the mulch in March may encourage the plants to bloom before the danger of frost is past. Temperatures of 32 degrees Fahrenheit or lower may severely damage or destroy open flowers.What turns into compost the fastest? ›
Some materials compost more easily than others. Materials such as wood and leaves are high in lignin, which is difficult to compost, especially when this material is large in size. Other materials, such as grass clippings and shredded paper, compost a lot faster.What breaks down compost faster? ›
Smaller materials break down faster than larger ones, and making sure everything is shredded is also a great way to create pockets of air within the pile to help aerate and speed up the composting process.
So, to sum up: yes, mulch can turn into soil over time, but how quickly this happens depends on a variety of factors. If you're using an organic mulch, it's likely that it will eventually break down and provide nutrients to your soil.Do wood chips turn to dirt? ›
Within 3 years it will be fully broken down and providing excellent nutrients to the soil. Treated woodchips will take longer, around 4 years to fully break down, with the start of decomposition occurring around 2 years after the mulch has been laid.Do you put compost over or under mulch? ›
Mulches can be applied atop compost or leaf litter to suppress weeds, add organic material, and reduce the evaporation of moisture from the soil. The layer of leaf litter or compost will provide extra nutrients and break down more quickly than the mulch.Is bagged compost any good? ›
Bagged compost is a good option for gardeners who want a ready-to-use product that is relatively low in cost. However, it is important to note that not all bagged composts are created equal. Some products may be lower in quality, while others may be too high in nitrogen for some plants.
Use bricks and pavers as a fire pit mat.
Putting concrete pavers under your fire pit will protect your grass. If you're using a fire pit on grass, it's important to use a fire pit mat. This will help protect grass from the extreme heat of the fire pit. You can use brick pavers as a fire pit mat.
We'd recommend using hardwoods, such as oak, ash and beech which are best for heat when cooking and will provide a long burn and flavour. If you're looking to add a little more flavour, Apple wood provides a fantastic flavour or why not try adding a little hickory at the end of cooking for a smokey taste.What can I burn in my fire pit without smoking? ›
5) Use naturally smokeless types of firewood.
These include hardwoods like oak and ironbark and softwoods like Australian cedar and pine. If you're looking to reduce fire pit smoke, try using one of these types as your main fuel.
For an annual bed, remove old mulch before you till the soil and add compost. If you're applying mulch to a perennial bed, you might be tempted to just add a new layer of mulch on top, but this can cause rot, nutrient starvation, and plant death. Remove as much of the old layers as possible before you add more.Why would you not want to use compost as mulch? ›
Because the uses for compost and mulch are different—soil fertilization and amendment vs. soil covering—it is usually not a good idea to use them interchangeably.Can I use old mulch as compost? ›
Old mulch can be put in your compost bin if made from organic material. However, the type of material used in the mulch will determine how long it will take to completely break down in the compost. For example, Woodier materials take longer to decompose than softer materials, such as straw.When should you not use mulch? ›
While mulching in early fall is safe, you should never mulch during late fall. "This can insulate the ground and prevent plant dormancy," says Morrell. The much-needed hibernation helps plants survive the cold winter months.Does bagged mulch go bad? ›
As long as it's dry, a sealed bag can sit indefinitely. Bagged mulch can go sour or moldy in wet areas, or even can attract pests, so proper storage is really all you need for a long-lasting product.How many years does mulch last? ›
Your mulch should be replaced every 1-2 years (on average). If your mulch seems to be less thick than when you first installed it, it is probably a sign that it is breaking down and dissipating into the soil. However, this is not the only reason your mulch might need replacing.Can mulch be used as fill? ›
In addition to beautifying your landscape, mulch helps prolong the life of your plants and keep your soil intact. Over time, mulch will break down and effectively become topsoil but it shouldn't be used in lieu of topsoil.
Fall mulching isn't for you if you like to leave perennial stems to provide winter interest and insect or bird shelter. If self-sowers play a large role in your plantings, skip fall mulching. That fresh layer could interfere with seed germination in spring.Is it OK to store mulch in garage? ›
Storing Bagged and Bulk Mulch
Then, simply set the mulch in a dry area for the winter, like a garage or garden shed. To store surplus bulk mulch, place the landscape material on a tarp and cover the pile with a second tarp to keep the supply dry.
If you happen to purchase mulch in bags and are concerned about any pests inside, you can leave the bag in the sun before spreading the mulch. Once the mulch reaches 120 degrees Fahrenheit for one or more hours, any bugs within the bags should be terminated.Should you cover mulch with a tarp? ›
Cover the top of mulch piles with tarp. Hold the tarp in place with stakes or weights. Keep the edges of the tarp off the ground to provide air flow.What happens when mulch gets old? ›
Eventually all mulch will decompose and no longer provide the benefits it was designed for. Organic mulches provide nutrients to your soil, while retaining moisture and protecting the soil. As your mulch decomposes or is reduced in depth, you become more likely to see more problems with soil erosion and weeds.Is it OK to put new mulch over old mulch? ›
For an annual bed, remove old mulch before you till the soil and add compost. If you're applying mulch to a perennial bed, you might be tempted to just add a new layer of mulch on top, but this can cause rot, nutrient starvation, and plant death. Remove as much of the old layers as possible before you add more.What should you not mulch with? ›
DON'T use rocks as mulch.
Warmed-up soil can lead to stressed, thirsty plants. Another problem with using rocks as much? Windblown weed seeds also nestle among the stones and root in all the nooks and crannies, making weeding even more of a chore.
Adding mulch on top of the soil is beneficial because it is a source of nutrients. It also helps with maintenance; you will have fewer reasons to water your plants because it encourages moisture retention. It also ensures an adequate and steady supply of the required nutrients.Is it better to mulch or not to mulch? ›
As you can see, the advantages of mulching far outweigh the disadvantages. Mulch is attractive and benefits the garden by reducing the loss of soil moisture, moderating soil temperatures and inhibiting weed growth. And, if organic mulch is used, it will improve the soil structure and add nutrients as it decomposes.