Mulch is essential for shrubs, trees, and perennial beds throughout the year, even when the plants are dormant. But what do you do with old mulch accumulated on the tops of annual flower beds or vegetable gardens over the winter? The plants died due to neglect or frost, and the food crop was taken. Is it still possible to use the old mulch? Is it necessary to remove it?
Should I remove my old mulch?
As long as the mulch has not degraded much, it is not necessary to remove it.
Picking some of it up will tell you if it is still usable. It could be replaced if it has broken down into fine particles like dirt. Alternatively, because it is organic matter, you can incorporate it into the soil, and it will perform a similar role as compost.
Usable old material will continue to decompose, contributing more nutrients and organic matter to your soil. It functions as a fertilizer with a delayed release.
It takes time and effort to remove the old mulch. Leaving it on the ground also means you won’t have to buy as much new mulch, saving you money.
Removing old mulch may potentially cause root damage to your plants.
If your plants in a certain garden bed developed disease last year and you suspect the mulch caused it, you should consider removing it.
You do not need to remove your mulch if it has been knitted together. With a rake, fluff the mulch and add more on top. If you see fungus or mold, use a fungicide or remove the mulch if it is significantly damaged.
If you use engineered wood fiber or another engineered material, you merely need to remove the old mulch completely.
Is it still safe to use old mulch?
Plants are not grown in vegetable garden beds or annual flower beds throughout the winter but mulched in the fall to protect the soil from the harsh environment. You’ve worked hard to improve the fertility of your garden soil, so you don’t want strong winds or torrents of water to wash it away, do you?
If the old mulch has not decomposed significantly by the time spring comes, it will still be usable. How do you tell whether it’s in good condition?
So, take a handful of mulch in your hands. Has it degraded to the point where it can no longer be distinguished from dirt? It will no longer be effective as mulch in such a situation, and it is time to replace it.
However, you can reuse it if it has substantially preserved its original look and feel. The only exception would be if your plants in this garden bed had disease problems last year that you believe was caused by the mulch.
If you think that the old mulch has not decomposed significantly upon inspection, you should rake it aside for the time being to prepare the planting bed. Shovel the mulch into a wheelbarrow and dump consecutive loads onto a tarp off to the side if you need to get it out of the way. Apply compost to the vegetable garden or annual flower bed with a spade and till it under or work it into the soil.
You can see why the initial instruction was to rake the old mulch aside: the old mulch would have been tilled or spaded under while you were rototilling or spading the compost into the garden, forcing you to get and apply fresh mulch. That would be a waste of time, effort, and resources.
But what if the previous mulch has degraded significantly throughout the winter? In such instances, work it into the soil as organic matter alongside the compost to serve as a soil amendment. Then, as a replacement, get a load of new mulch.
What about “living” mulches or cover crops?
Although the terms “cover crops,” “green manure,” and “living mulches” are more commonly used in agricultural circles than in landscaping circles, some homeowners may find cover crops to be quite beneficial.
Cover crops should be selected based on where you live. Legumes such as clover, hairy vetch, peas, beans, oats, annual ryegrass, winter rye, wheat, rapeseed, and buckwheat are among the cool-season options. Warm-season crops include cowpeas, buckwheat, soybeans, and sorghum-sudangrass.
The crops are sown over vegetable gardens and annual flower beds in the fall to shield them from winter. When spring arrives and you’re ready to sow again, it’s time to pull out the cover crop. Tilling cover crops frees up space in the garden for spring planting while also adding nutrients to the soil.
Mow the cover crops first, then run a garden tiller over them, a procedure known as tilling under. Because you will be tilling shorter vegetation if you mow first, the tilling will be easier. After mowing, sprinkle compost over the same garden bed and till it under, just like you would with other beds that did not have cover crops.
Recycling old mulch
You can still use old mulch if it preserves its texture and size. It can continue to serve as a healthy soil cover.
Though throwing out the old mulch may be tempting, don’t underestimate its worth.
It can still benefit your soil in the following ways:
- Weed barrier
- Moisture retention
- Ground cover
It may, however, be too settled and insufficient to offer proper coverage on your bed soil. A 3 to 4-inch layer of mulch is recommended. Replace old mulch with new mulch to provide adequate coverage for the bed soil.
After a growing season, old mulch will inevitably compact and cluster on the ground. You can loosen the mulch with a rake and store it in a wheelbarrow or by the side of your garden. Check to see if it can still be used as mulch.
Once the qualities of the mulch are still distinguishable from the old mulch, you can replace it on top of your bed.
Maintain a thickness of 3 to 4 inches and replace mulch as needed. The thickness of the mulch in your bed is critical to its efficacy.
Mulch that is too thin will not keep tenacious weeds out of your bed, while mulch too thick will hinder water absorption in the soil.
Tips for reusing old mulch
Mulch goes through the growing season and dormancy the same way plants do.
Mulch becomes a second home for overwintering and soil-borne pathogens and pests when it becomes infected with insects.
So there are certain exceptions when it comes to reusing old mulch. These include:
- Do not reuse old mulch from plants infected with fungal diseases such as early blight, root rot, and wilt disease.
- Inadequate mulching also contributes to the spread of plant diseases. Something occurs when the fruits and leaves come into contact with the soil. As a result, make sure to keep the mulch thickness consistent.
- If you reuse old mulch, it will most likely be faded and less colorful than new mulch. And since it is still beneficial to the soil, you can apply a mulch renovator to bring back its rich brown color.
- Avoid staining your concrete pavements by storing old-colored mulch on a tarp.
- Some pests, such as larvae, can hide in the mulch and survive the severe winter season. If your plants were infested this year, it is advisable to remove the mulch entirely.
- Rake the old mulch away during soil preparation to allow the soil to breathe and water to reach the topsoil. Reusing old mulch saves you money on new mulch for the following growing season.
- Avoid volcano mulching on trees or tree seedlings since it can suffocate and kill them.
- Never add new mulch to an existing hard layer of mulch.
- Loosen the old mulch with a rake first to allow the soil to breathe properly.
- After a few months, turn the mulch around to loosen the compacted top layer. Molds on the top layer can be prevented by loosening the mulch regularly.
Repurposing old mulch
Mulch that has been reused for a long time can wear down over time. Because it is an organic matter, it degrades after exposure to the harsh sun, winter, and water.
Dealing with worn-out plastic mulch, on the other hand, is a different matter.
If the old mulch is nearly decomposed, use it as a soil addition during preparation.
Before putting old mulch into the soil, mix it with compost for improved performance. Allow the compost and mulch mixture to combine on the bed soil with the spade. Replace the mulch on top of the bed as needed.
Grass clippings are a wonderful mulch for plants, according to Dr. Chalker-Scott of the University of Vermont, but they decompose faster than other types of mulch.
If it decomposes, you can mix it with compost and incorporate it into the soil as an organic soil additive.
She also stated that wood chips are the best mulch for trees because they can hold water slowly released into the soil and more effectively reduce the soil temperature. Mulch, as a fertilizer, operates similarly to fertilizer with a 4-1-2 NPK concentration of 4% nitrogen, 2% potassium, and 1% phosphorus.
Tips for repurposing old mulch
Most gardeners save money by using existing mulch as a soil amendment instead of purchasing new soil amendments on the market.
However, there are some situations when old mulch and wrong mulching practices might do more harm than good to your plants. These include
- Mulch made of wood materials should be mixed with compost before being used as a soil addition. Wood eats nitrogen, which can interfere with the nitrogen distribution in your plants. When old wood mulch is combined with compost, microbes accelerate decomposition and make nitrogen readily available to your plants.
- Sawdust, in particular, is known for causing greater soil damage than wood chips. It and other wood products should not be used uncomposted since they may hold up nitrogen, alter soil preparation, and upset your plants’ healthy processes. Wood alone decomposes slowly and requires the assistance of other organic substances to disintegrate properly.
- Accelerate the decomposition of wood products by adding nitrogen-dense organic resources such as manure or grass clippings.
After mowing your grass, let the clippings settle on the soil. It is a natural fertilizer and saves you money on lawn plant food.
You should cut the clippings into smaller portions to settle and decay properly on the soil and avoid matting.
When should new mulch be added?
You can keep the mulch if it is still substantially intact. Rake the mulch to the side or onto a tarp if you want to amend the bed with compost and add fresh plants. When you’re finished, replenish the mulch around the plants.
Especially shredded wood mulch forms a mat that can prevent water and sunshine from penetrating.
Aerate the mulch with a rake or cultivator and, if necessary, apply more mulch.
However, if the matted mulch shows any signs of fungus or mold, it should be treated with a fungicide or removed entirely. Mulch not only degrades but can also be shifted by foot traffic, heavy rains, and wind.
The goal is to have 2 to 3 inches (5-8 cm) of mulch on the ground. Lightweight, broken-down mulch (like shredded leaves) may need to be renewed twice a year, whereas heavy bark mulch can remain for years.
How to change mulch
If you’ve decided that last year’s mulch has to be replaced, the next question is how to dispose of the old mulch. Some gardeners remove the mulch from the previous year and add it to the compost pile.
Others believe that the broken-down mulch will improve the soil’s tilth and either leave it alone or dig it in further before applying a new layer of mulch.
Consider changing your garden mulch if it is less than 2 inches (5 cm.) in your flower beds and far less than 3 inches (8 cm.) around shrubs and trees. If you’re down an inch or two, you can also top off the old layer with just enough new mulch to make up for the difference.
What to do with faded old mulch
So, while your mulch has lost part of its color, it is still in fine shape. What are your options?
There are numerous environmentally safe mulch dyeing options. Unless you specifically requested a natural color, your mulch was pre-colored when you purchased it.
Mulch dye is often composed of one of three naturally occurring materials:
- Carbon: The colorant for black mulch dye is a carbon (or charcoal).
- Vegetables: Most mulch colorants are vegetable-based, which means they are safe for the environment.
- Iron Oxide: Iron oxide is made up of iron and oxygen, or rust as we know it. This is the preferred dye for reddish mulches.
What to do with mulch that hasn’t decomposed completely?
After evaluating your mulch and determining that it has not degraded too much, rake that old mulch away for the time being so that you can prepare the bed for planting. If you want to get that mulch out of the way, shovel it into a wheelbarrow before transporting it to a tarp on the side.
Apply compost to your vegetable garden or flower bed and either till it under or work it into the soil with a shovel. This creates the ideal environment for planting your annual flowers or veggies, ensuring they receive the necessary nutrients and growing room.
Return the old mulch to the vegetable or garden plot when you’re finished tilling. This entire process can be completed well ahead of the actual planting period. Remove the mulch from the area where you are transplanting plants or sowing seeds when the time comes.
Weeds won’t be able to sprout with your mulch in situ, causing you more hassle than you’d like.
What if the mulch has decomposed too much?
Maybe you have mulch that has deteriorated too much to use in your garden bed. It can be worked into the soil as organic materials. When combined with compost, this acts as a soil amendment. Then, go out and get some new mulch to replace it.
Cover crops are still used in various ways — they are referred to as “living mulches.” Cover crops are more commonly used in agriculture than landscaping, although some homeowners have found a good use.
Cover crops are often sown in the fall into your annual flower or vegetable garden area to protect them from winter. When spring returns and you’re ready to plant again, you’ll need to get a cover crop out of the way.
What do you do with old mulch when composting isn’t an option?
Composting is not an option if you have a limited area or colored mulch. You’ll need to bag the old mulch and take it to your local garbage disposal center. Never, ever, ever burn old organic mulch!
If bagging up old mulch isn’t your idea of a fun afternoon, you can have it removed by a professional landscaping company.
Is it necessary to refill mulch every year?
No, not always. Mulch should only be replaced if it exhibits signs of decomposition or comes from plants infested with pests and diseases. Otherwise, you can continue to use it as mulch and add new ones to retain the proper layer thickness.
Is it still possible to use rotting mulch?
Yes. You can still use mulch stored long enough for mold to take over. Spread it on concrete and allow the sun to sterilize it before removing the mulch molds. If ants or other pests start to make their way into the mulch, you can control them with soapy water.
What type of mulch has the longest lifespan?
Bark mulches have a lifespan of 7 to 10 years. Because of its resilience to decomposition, cedar mulch, in particular, lasts. The oils also deter insects in cedar mulch. They do not contain as many nutrients as other types of bark mulch.
Mulching is an art to master if you understand how each type of mulch impacts your plants.
We hope you reuse or repurpose your old mulch to maintain it as it decomposes.
To prevent pests and diseases from spreading to other crops, diseased plant mulch must be disposed of.