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7 Things You Can Do With Old Mulch

7 Things You Can Do With Old Mulch

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Mulching materials don’t come with a use by date. You have to determine when they are too degraded to serve their purpose. Then comes the point of figuring out what to do with the old mulch.

Some materials can simply be raked aside and bagged or boxed for shed storage, others may be done with in which case, it can be upcycled if it’s bio-degradable.

Inorganic mulches should last for decades, but even then, if you want to change your landscape from colored shredded rubber or any type of manufactured materials that’s been used for mulching around your yard, there are ways those can be upcycled too.

Organic mulches can be repurposed for so many garden projects. Below, you’ll find a list of 7 projects that could see your old mulch reused in the garden that’ll last for years.

First though, what’s the difference?

Inorganic Mulch vs. Organic Mulch

Organic mulch is anything that could be put in a compost pile to make compost, eventually. That can take a while though. The benefit to using organic materials for mulch is that as it decomposes, it turns to compost, putting nutrients directly back into the earth.

Inorganic mulches are anything that doesn’t provide nutrients to the soil. Examples of inorganic mulch materials include synthetic rubber mulch, reflective metallic mulch, gravel, pebbles, rocks, and the usual weed membranes that are put beneath hardcore to suppress weeds.

The ways you can use old mulch may be determined by the climate in your local area. As an example, leaf mold and wood chips are terrific for holding moisture. That makes them beneficial for natural garden paths.

However, if you don’t have sufficient rainfall to compact the materials sufficiently, it’s more likely to blow away, unless you have put something in to keep the mulch in place (gravel boards are handy for paths).

7 Ways to Repurpose Old Mulch

1 – Apply a Mulch Dye

Before you start renewing your mulch because it is faded, know that you can just dye it. Dying faded mulch is the simplest, budget-friendly way to increase the aesthetic lifespan of it.

It has one BIG drawback though. Only the top layer of mulch will be dyed. Wildlife trotting through dyed mulch, or some of it being blown out of place by the wind is likely to lead to patches where you have the dyed mulch blending with the untreated mulch beneath it.

There isn’t much choice in colors though because with organic materials, you should be using organic dyes. In that category, only red and black or brown contain no harmful chemicals.

Red mulch dye is made from iron oxide, whereas the darker brown or black mulch dyes are made from carbon products. Any other color of dye is likely to contain chemical additives that would alter the chemical profile of your soil. Not good for your plants.

Chromated copper arsenate (CCA) is the usual suspect for dyed wood chips or colored bark, which can come from treated wood being shredded to make the dyed mulch from the likes of old crates, shredded wood from pallets, or recycled decking panels or fence posts.

The risk of dyed mulches being toxic to plants is more of a concern if you use colored mulch like black wood chips, or brown bark containing synthetic chemicals. It depends on the original source of the wood. Recycled wood that’s been treated at any time can contain chromated copper arsenate (CCA).

2 – Make a Compost Heap

Compost heaps are ideal for biodegradable mulch. The finer the materials, the faster they decompose.

Better yet, a compost heap is a wildlife haven, so long as you build it on top of soil and not within a container with a bottom to it. On soil, worms and other small insects can make their way in, helping with the decomposition process as they munch their way through it.

Larger wildlife like birds can seek shelter, while predatory insects feed on slugs, beetles, flies and similar invertebrate, and when birds visit, they feed on insects and seeds.

There is one exception to be aware of when composting mulch. If it’s dyed, it can leach chemicals into the compost and that can then make your soil toxic to the plants you use it with.

Avoid composting dyed mulch, unless you know for sure that the dye used is organic. Otherwise, it takes longer to compost and leaches chemicals.

3 – Use the Compost from Organic Mulch to Prevent Soil Erosion

One of the many benefits of organic mulch is that once it decomposes, the compost becomes a soil additive. Naturally, any soil is prone to erosion. Rather than spend your cash on replenishing top soil, simply use your organic compost as top dressing instead.

As you wander around your yard, look for key areas where soil is eroding. The usual spots are areas that are walked on, played on, or if you have dogs that tend to run rings around the fence perimeter, there may be ditches forming that could benefit from a mulch being added to top up the soil, and level it off, even if slightly.

Mulching around garden perimeters can make your edging tasks much less labor intensive, too.

4 – Form a Path Through a Vegetable Garden Planted in Rows

Vegetable gardens that are planted in rows can be easier managed by using old organic mulch to make a temporary walkway between the rows. A thin layer is all that’s needed. Once it’s time to till the soil, you can work the old mulch into it, ready for the next season’s sowing.

Some materials are better suited to walkways between rows of vegetable garden rows. Straw is highly advantageous as it’s inexpensive and easy to till into the soil and replenish each year.

5 – Use As an Amendment in Potted Plants

Potted plants can benefit from the improved aeration and water retention of old fine mulch that’s decomposed. Just like when using old garden soil, when using compost made from mulch for indoor plants, it should be sterilized first.

If you have old inorganic mulches like shredded rubber or reflective metallic mulch material, those are heavier making them beneficial as a base liner in potted plants. Heavier mulch material is good for weighing pots down, preventing large container plants from toppling over.

6 – Use As Filler in a Raised Garden Bed

It’s perfectly fine to layer the base of a raised garden bed with mulching material. As it decomposes, it’ll enrich the soil above it, saving you on fertilizer costs, and you’ll use less volume of soil to fill the raised bed.

Keep that in mind if you or anyone you know buys a real Christmas tree, whether it’s a spruce, fir, or pine… chop it up and it’s fresh mulching material.

There’s a kicker though. Wood mulches in soil bind the nitrogen, meaning your plants won’t do great. A workaround with this is to apply a thin layer of dried grass clippings as mulch over the topsoil. As the grass breaks down, it’ll replenish some the nitrogen content.

If you use too much wood mulch, there’s going to be little nitrogen availability for the plants, until the decomposition process kicks in, usually around a year later. Until then, focus on growing shallow rooted plants that aren’t heavily reliant on nitrogen.

Ideal plants are root vegetables like carrots, turnip, and radish plants because they have a preference to develop the root system rather than sprouting foliage.

7 – Use Rubber Mulch As a Filler for Bean Bags

Rubber mulch is softer than grass making it a good material for kid’s play areas. Layers of old rubber mulch are placed under swings, a climbing frame, at the base of slides, or the bottom of ladders to a treehouse to provide a softer landing zone for kids. That’s often the reason for installing it.

If you’re done with your play area, see if someone else could be doing with it or sell it through an online marketplace.

Once you’re done with rubber mulch in your landscaping, it can be upcycled as a filler in bean bags, or pillows.

What to Do with Old Mulch That Can’t Be Composted

Not all organic mulches are suitable for composting. Sometimes, they become unsalvageable. Fungal diseases are a common problem that renders the mulch useless.

You can usually tell when the mulch has gone bad just by it’s smell. It stinks. Like rotten eggs. Putting disease ridden mulch in the compost pile will spread those pathogens wherever you were to use the compost.

The only thing that can done with bad mulch is dispose of it at your local landfill or waste management facility. Most local landscape companies provide collection and disposal services if you don’t fancy spending the day bagging and disposing of yard waste.

Can Old Mulch Be Burned?

Some areas have restrictions in place forbidding the burning of garden waste. If your area permits small fires in the garden or using a fire pit, old mulch can be burned. Just be sure that you take the usual safety precautions and do your best not to inhale the fumes. Some of the pathogens in old mulch can be toxic.

Best practice for burning garden waste is ensure everything is dry. The damper the material, the more smoke is produced.

It’s not uncommon for mushrooms to grow in mulch when the moisture content is too high. If you have a large pile of old mulch, separate it into smaller piles so that it can aerate, helping it dry out quicker.

Once it is dry, it can be burned somewhere safe, away from anything flammable and preferably in a fire pit or a garden incinerator rather than an open fire where a strong breeze can blow the flames in any direction and the embers from the mulch.

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