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While working on my gardens this spring, I was raking up the mulch and stopped to wonder. Do I need to replace the mulch each year, or is it acceptable to leave from one year to the next? After all, that would save a lot of hard work and money, so I decided to do some research.
Old mulch does not usually need to be removed and is often acceptable to leave undisturbed. It should be removed if it is infected with fungi or if the plants it surrounded were diseased. You’ll want to check the mulch to ensure it is effective and hasn’t matted itself down, choking off your plants’ access to air and water.
More about the assessment of old mulch, layering mulches, and reusing old mulch will be covered in the following sections, so read on!
Checking the Condition of Your Old Mulch
When you see if you can reuse your old mulch, you need to assess its condition. After all, if it has broken down too finely, it’s not going to make a very effective ground cover around your plants. In general, organic mulches last for approximately 5 to 6 years, although as they break down, you may need to add mulch every other year.
Throughout all of this, you want to keep the effect of mulch at the forefront of your mind: sure, it looks decorative when mulched appropriately.
Good mulch is so much more than an adjunct to your landscaping efforts, as mulch protects the ground and helps keep the soil around your plants moist.
It also helps retard the growth of weeds, minimizing the work you need to do to keep your plants healthy.
Did your plants grow well with your old mulch?
Start by assessing last year’s garden beds, whether they were flower beds or vegetable gardens. Did any of the areas have diseases that may have contaminated the mulch? If the mulch caused disease.
If you answered yes to either of those questions, you should consider not reusing your old mulch instead of fresh, new mulch.
You also want to inspect your old mulch visually. Are there any areas that may be affected by fungi? While you can potentially cover those areas over with fresh mulch, choking off the fungi’s air supply, you’re probably better off getting rid of that mulch. Check with your city on how best to dispose of old, infected mulch.
Assess the mulch particles of your old mulch closely
Now it’s time to check out the state of your mulch. Scoop up a handful or two and look at the mulch. Has the mulch kept its appearance of thick pieces of mulch, or has it broken down into fine particles that you can’t readily distinguish from the dirt filling your garden?
If it has broken down into delicate particulate matter, you will not effectively use it as mulch. Don’t despair, though: you can still salvage the mulch, at least to an extent!
Reusing Your Old Mulch
If you’re reusing your old mulch, it’s time to do a little heavy lifting.
Raking out your old mulch
Start by raking your old mulch off to the side of your garden bed. You might need to shovel it out of the garden to allow you room to prepare the beds for this spring, so consider putting it in a wheelbarrow or setting it on a tarp near your bed while you work.
Mix your old mulch with the compost when preparing your garden beds
Now it’s time to prepare your garden beds for planting. Add compost to the garden bed, either by tilling it into the soil or using a spade to work it into the ground. Here’s where you can reuse your old mulch if it has become finely ground over the year.
Once you’ve applied your compost to the bed that still has the old mulch in it, rototill or break it down all under, mixing the compost into the ground with your mulch.
If you are readying your garden beds well in advance of planting, you can spread the old mulch back over the beds until it is time to plant, simply removing the mulch from the area you are about to grow in. Your other option is to leave the bed open and plant your plants in it, then spreading the old mulch back around the plants.
What If You Use Cover Crops?
Cover crops are often utilized in place of mulch during the fall to help protect the ground during the winter months. These plants are also frequently dubbed “living mulches.”
Cover crops are very effective in that they build soil structure and help support microbial life while mulching the garden. There are hundreds of different plants that can be used as a cover crop, and you can learn more in this article I wrote, where I take you through each of them and their benefits for your garden.
How to use cover crops
If you use cover crops or living mulch during the fall, you’ll want to prepare your garden a little differently than if you were using regular mulch or straw. With these crops, you till them under when you start to prepare your spring gardens.
Using cover crops offers two advantages: you free up space for your spring vegetable or flower gardens, and you are also putting nutrients back into the soil.
Start by mowing the crop short, which will help you till the cover crops into the soil. Then run your garden tiller like you usually would. Adding compost is still recommended to amend your garden.
In the video below, I take you through everything you need to know about cover crops, why they benefit your garden, and the best ones to use. I am sure that if you are reading this post, you will love the information in the video too.
Considerations for Mulching
When you mulch your garden beds, you need to check the mulch levels carefully and ensure that you don’t pile up mulch directly around the base of your plants, trees, and shrubbery.
Doing so can affect your plants’ health, potentially even leading to the premature death of your plants.
Choose your mulch appropriately for specific garden needs
Just like with everything, certain plants foster and thrive under certain conditions.
In the following sections, we will discuss how a particular type of mulch is not advisable for perennials as an example, but this proves careful thinking of what you plan to mulch for your plants.
In general, there are two types of mulch, that being inorganic and organic.
They have different longevities due to external factors, particle size, and how fast their material decomposes. The different types of mulch under organic and inorganic mulch are described in detail in this recent article of mine on the best mulches in the garden, where I discuss different mulch types like wood, compost, and leaf mulches, well as their making process and benefits.
Place mulch on your plants with an appropriate amount and depth
Generally speaking, when you mulch around your plants, you want to mulch to an approximate depth of 3 to 4 inches. (source) Mulching less than that will be less effective at helping your plants maintain their moisture content and preventing the growth of weeds. If you mulch too deeply, you can strangle your plants because they cannot get water and air to the roots.
It would be best to be careful with the amount of mulch you apply, especially over plants like perennials.
Certain plants are highly susceptible to the amount of mulch that gets applied, such as peonies, which may not flower if they are mulched over. Plant species with shallow roots should be mulched over carefully, or you could smother the plant’s roots.
Don’t do mulch volcanoes
When you mulch around your plants, you also don’t want to place the mulch directly against your plants. Forming so-called mulching “volcanoes” can cause diseases by retaining too much moisture against the plant.
In trees, this can affect the phloem, the layer of living tissue under the bark that helps transport water and nutrients throughout the plant.
Some diseases such as fungal infections or parasite issues are also more common when the mulch is placed adjacent to the plants.
Cultivate the mulch carefully
Especially when you are reusing mulch, you need to cultivate the mulch carefully. Breaking up the chunks of mulch that pack down for the year helps to allow air to reach the roots of your plants.
Without breaking up these mulch clumps, your plants won’t get enough air to their roots.
These mulch mats can also prevent water from reaching the roots of your plants instead of causing the water to run off the mulch. It is pretty easy to cultivate your mulch.
Take a pitchfork and fluff up the mulch gently. Do this before adding new mulch (if you need to add any) for the best results.
Keep certain mulch types away from perennials
Some people choose to place black plastic or weed retardant fabric. These are not generally recommended for placement around perennials, but they can be valid for around annuals.
As the perennials grow, these weed barriers can impede the plants’ growth. Consider instead using newspaper as a weed barrier, which will eventually break down and add organic material back into the soil.
Conclusion on the removal of old mulch
Old mulch can be hugely beneficial to your garden beds, replenishing the ground with biodegradable material just as long as it is ensured that they had not come into contact with pests and diseases when you initially used them.
Keep in mind if you’re using plastic or another similar material inorganic mulches, you can’t wait just till it under like you can with old mulch that has broken down. If the material hasn’t decomposed significantly, you can always rake it to the side and reuse it.
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