A year has passed, and the mulch in your garden is looking quite drab. It’d be easier to get rid of it but is there any other way you can use it again?
As a whole, old organic mulch can be reused, provided it still retains most of its original structure. This is often topped up with new mulch after raking the old one to freshen it up. But it can also be upcycled into compost, as long as the previous plants weren’t infected or infested.
Below, I discuss these further, along with helpful tips. But first, a brief introduction to mulches …
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Table of contents
What is Mulch?
Mulch refers to a layer of materials spread on top of the soil to support a plant’s growth. It is often used for the following purposes:
- Prevent too much water loss from the earth.
- Keep the ground warm or cool according to the seasons.
- Suppress weed growth
- Protect surface roots and trunks from damages caused by lawnmowers or weed trimmers.
- Add aesthetic appeal to the landscape.
- Provide nutrients to the soil and improve structure as it decomposes.
There are generally two types of mulch, namely: organic and inorganic. The main difference between the two is that the former naturally breaks down over time and nourishes the soil, while the other doesn’t. Due to this, they need to be top up every now and then.
Organic mulch typically used are pure bark, pine straw, newspapers, dried grass clippings, and shredded leaves. Wood chips, sawdust, and straw/hay are sometimes used, but these usually come with a certain set of problems. For example, wood chips and straw/hay may sometimes come with seeds that will sprout into weeds. Sawdust also tends to clump easily and prevent water from penetrating the soil.
On the other hand, inorganic mulch often used are gravel, plastic, and landscape fabric. The latter is more commonly used because it’s more functional and safer to use than the other two. However, the downside is that repeated sun exposure will damage the material quickly, allowing weeds to grow through the fabric. This is why they are often paired with another layer of mulch like gravel or bark to protect it.
For this article, I’ll only be talking about old organic mulch. Inorganic ones are not necessarily reusable and are best discarded once damaged. However, it’s worth noting that gravel doesn’t break down. But they will sink into the ground over time if no landscape fabric is placed beneath them. They’re also usually used for decorative purposes. You can read this article on ‘Rock decor around trees’ for more information.
What Are The Best Things You Can Do With Old Mulch?
There are 3 things you can do with used organic mulch:
1. Reuse the organic mulch if it hasn’t broken down completely into dirt.
You’ll need to rake the mulch to break up any clumps and scoop some in your hands for a closer look. If the material looks the same as before, it’s still viable. But you’ll need to remove it and set it aside on a tarp or a wheelbarrow first. This allows you to water the soil directly, till the ground, pull any weeds, and uncover lurking creatures. Then you can spread the old mulch back on top, finishing with a thin layer of fresh mulch. This helps to keep the used layer from being blown away by the wind. However, maintain the overall mulch to only 3-4 inches in depth. Keeping a thin layer prevents pests from hiding in it and makes it easier for water and air to pass through into the soil.
However, suppose the mulch has broken down and resembles crumbly soil. In that case, you can simply add new mulch after raking the ground entirely.
2. Upcycle the used mulch by dumping it in a compost pile to decompose thoroughly.
Sometimes, we want to swap the old mulch with a completely new batch. But rather than throwing them out, you can compost them instead. This primarily applies to organic material that hasn’t decomposed much into the soil. You can refer to this composting article to help you get started. However, if it has already broken down, you can just till the ground to thoroughly mix it with the soil before adding fresh mulch.
3. Discard the old mulch entirely if it has been infected with pests or diseases from the previous plants.
You can’t salvage these mulches regardless of how small the infected/infested area is. Otherwise, you risk transferring the same pathogens to the new growing plants. Don’t also dump it into your compost pile because you may end up contaminating it as well. Where possible, look up your local area’s yard waste disposal service to get rid of it properly.
Helpful Tips When Handling Old Mulch
Here are a few valuable tips to keep in mind when dealing with used mulch:
- Always ensure the ground is weed-free before laying down your mulch. Otherwise, this will grow right through the organic material. Some weeds are persistent and need to be pulled out completely, including the roots, to prevent further spreading.
- Apply fresh mulch for new plants right after planting them. For established plants, early spring is the best time. This gives the soil time to warm up before weeds pop up. If you apply it too early, you risk keeping the soil too cool from the previous winter and delaying plant growth.
- Water the mulch lightly after applying to ensure it doesn’t get matted. Otherwise, this will allow the fungus to grow over it, preventing water from penetrating the soil. If your mulch does become matted, use a rake to separate them.
- Do not apply new mulch every year. Organic materials have varying decaying rates according to factors like weather and composition. Some may benefit from monthly reapplication, while others in yearly intervals. Check on your mulch every 6 months just in case. It’ll probably need raking or topping up if it is less than 3-4 inches from settling into the soil.
- Do not pile the mulch up against the plant’s stems and trunks. Otherwise, it will trap moisture, causing the bark to decay and providing an open wound for diseases or pests to infect or infest the plant. This is why giving 3-4 inches of space between the mulch from the trunk is essential.
- Discard any fungus found growing from the mulch. Most of them are harmless except for a few mushroom and toadstool species. So removing them is best to prevent pets and children from accidentally picking and ingesting them. Wear protective covers and wash your hands thoroughly after handling them.
Frequently Asked Questions about Mulch
Organic mulch decomposes over time, adding nutritional benefits to the soil and improving its structure. However, inorganic mulch like plastic, gravel, and landscape fabric does not break down. These are best discarded once they are damaged.
Organic mulch is not often used as a fertilizer for plant growth, but they do nourish the soil once broken down. But it’s best to use proper fertilizers like compost or pellets because they provide nutrients readily to the plants.
Organic mulch doesn’t last long, which can be a disadvantage to some people. Inorganic mulch lasts longer but doesn’t provide nutrients like the former. But at the end of the day, mulching plants have far more benefits in ensuring your plants’ best growth.
It’s necessary to remove old mulch before adding a fresh batch. This helps to break up any matted parts and reveal hidden pests. Use a rake to loosen the compact mulch, then temporarily place it on a tarp or wheelbarrow. This way, you can quickly till the ground, saturate it, and remove weeds. 
Early spring in March or April is the best time to apply mulch to established plants after the soil has warmed up. But you can also set it down in late fall during September or October, just before the ground becomes frozen. This gives the mulch time to decompose and settle into the soil before winter, giving your perennial plants that extra layer of protection to survive through the cold season.
Generally, it’s best to replace mulch every 1-2 years, depending on the material used. For example, shredded leaves decompose fast and may need to be raked and topped up within a few months. But bark or wood chips take a while to break down, so replacing them a year or more later is not unheard of.
Mulch may attract bugs that are not necessarily harmful to the material or the plant. However, if the mulch layer is over 3-4 inches in depth, this may attract pests that can hide underneath it and feed on the plant. But most of the time, you don’t really have to worry about this as the bugs that visit your garden can be helpful. You can read this Beneficial Bugs article to find out more about it.
Mulch is beneficial for trees because it helps to conserve moisture, moderate soil temperatures, and protect roots from extreme weather conditions. Mulch also reduces weed growth and can improve the overall health of your trees.
Organic mulch adds nutrition to the soil when it decomposes, encouraging plants to grow better. This is why most gardeners prefer using them to protect their plants better and nourish the ground as they develop. Inorganic mulch, however, doesn’t have the same nutritional benefits and can sometimes be a hassle.
Final Words
Overall, you can make more use of your organic mulch long after it has broken down. Even though inorganic mulch functions similarly, it doesn’t hold a candle to how versatile the former is. But at the end of the day, it comes down to your preference. Happy planting!
References:
- Choosing and Installing Mulches – Gardening Solutions – University of Florida, Institute of Food and Agricultural Sciences. (n.d.). Gardeningsolutions.ifas.ufl.edu. Retrieved August 17, 2022, from https://gardeningsolutions.ifas.ufl.edu/care/planting/mulch.html
- Excess Mulch Problems | University of Maryland Extension. (n.d.). Extension.umd.edu. https://extension.umd.edu/resource/excess-mulch-problems
- Jun 20, F. | H. 1604 | U., & Print, 2016 |. (n.d.). Mulch. Home & Garden Information Center | Clemson University, South Carolina. https://hgic.clemson.edu/factsheet/mulch/
- Mulches for Home Grounds – 7.214 – Extension. (2018). Extension. https://extension.colostate.edu/topic-areas/yard-garden/mulches-for-home-grounds-7-214/
- Mulching for a Healthy Landscape Inorganic mulches. (n.d.). Retrieved August 17, 2022, from https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/426/426-724/426-724.pdf
