For the most part, mulching is extremely beneficial to plants, although as with everything in life, so does mulching as well has its fair share of disadvantages. The good news is that the advantages of mulching outweigh the disadvantages. There is such a thing as too much of a good thing, and far too many people think the more mulch they use the better results they will get, which often backfires.
The disadvantages of organic mulches like hay, grass, wood chips, and straw are that they tend to attract a lot of pests, and if you are over mulching you could cause root rot or damage the plants. On the other hand, the disadvantages of using inorganic mulches like plastic and rubber are that they will dry out the soil and basically cook your plants on the hot summer days.
One of the main issues you with organic mulches will be with slugs and snails, my personal recommendation is to use a slug pesticide that is effective even after it rains Click here to check it out on Amazon.com
No matter if you are using organic or inorganic mulches they all have their disadvantages, some of these disadvantages can be worked around but in some cases, you will need to remove and redo the mulch. Location is very important when talking about the disadvantages of mulching, mulches will behave in different ways in different climates. Some organic mulches break down extremely fast in some areas while in other areas they turn into an anaerobic environment which slows down the decomposition process significantly.
If you are new to mulching, then you have to keep an eye out on it for the first year, and don’t be afraid of trying out new mulches in the meantime. If you want to know what are the benefits of mulching then check out my recent article Benefits Of Mulching ( Top 13 Pros Of Mulching ).
Mulches Can Attract Pests
Organic mulches tend to attract a lot of different pests, from slugs, snails, to larger pests like mice, rats, rabbits, and even deer. Pests that feed on dead or decaying plant matter will love your organic mulch. Not only do most organic mulches feed the pests but they also shelter them, especially slugs and snails as they do love a moist environment that organic mulches do provide. Mulches made out of grass clippings, hay, straw, and even wood chips will attract pests, so make sure to keep an eye out on them.
The good news is that most of these garden pests will feed on the mulch and not on your plants. The bad news is that you are making an ideal environment for the pests to live and reproduce in.
Mulches Can Damage Plants
If done incorrectly mulches can actually damage the plants, this is why it is extremely important to mulch around the plants and not piling the mulch on them. As the mulch breaks down it releases a lot of nitrogen, which is beneficial for most plants but small plants tend to be extremely sensitive to high nitrogen in the soil. In addition to this if the mulch is in direct contact with the stem of the plant it could make the plant prone to different diseases.
Most mulches are excellent at retaining water, although if the stem of the plant is constantly wet then fungal growth can occur which eventually will kill off the plant. This is the same case for trees as well, so never pile mulch on the base of trees for more information check out my recent article Grass Clippings Around Trees ( Top 5 Do’s ).
Over Mulching Can Cause Root Rot
There is such a thing as over mulching, which can simply destroy the topsoil. Mulches are excellent at retaining water, and the thicker the layer of mulch is the more water it will retain. If there is too much water in the soil then anaerobic bacteria will start to take over as the more water in the soil is the less oxygen it can contain. This means that the beneficial bacteria, bugs, and critters like worms will simply leave the mulch and the anaerobic bacteria will make a mess out of your mulch.
You will know when anaerobic bacteria have taken over your mulch when the mulch starts to smell, and when it started to compact in something that resembles layers of carpet. The bad news is that most plants need oxygen for their roots to develop, this is why aerating the soil is extremely important. By over-mulching your plants will slowly rot away starting from the roots, so make sure to add mulch only when it is needed and not when you have excess mulch and don’t know what to do with it.
Mulches Can Cause Nitrogen Build Up
Mulches will cause a nitrogen buildup while they are decaying, this becomes a massive problem if you mix the mulch into the soil. Nitrogen is good for the plants, but only in moderation, if you have a lot of nitrogen in the soil it could damage the roots of the plants. This is especially problematic if you tend to have a lot of young plants, so make sure to only use the mulch on top of the soil and do not mix it into the soil.
Mulches Can Contain Herbicides
Herbicides are used to get rid of unwanted plants, and the worst part about them is that they will linger in the soil for years. If you are using your own mulch then you should be safe, but be extremely careful of bringing in someone else’s mulch or compost. Animal manure can also contain herbicides, as most herbicides will simply pass through the gut of the animals, and if you are using this manure as mulch then you will be scratching your head why your tomato plant leaves are curling up and dying suddenly.
Weeds Can Grow Through The Mulch
Mulches are mostly used for keeping the weeds out of the vegetable garden, although this doesn’t mean that the occasional weeds will not pop up. Most native weeds are extremely hardy and almost impossible to get rid of. If you are using organic mulches like hay, grass, wood chips, or straw as mulch then you will still see some weeds growing right through the mulch. The good news is that your de weeding time will be significantly reduced, and weeds can be easily plucked out of the mulch.
Mulches Can Contain Weed Seeds
If your mulch is made out of hay, grass clippings, or straw then it will contain some weed seeds. Although this isn’t really a big problem as most of your garden will contain a lot of weed seeds brought in by birds, and by the wind. Straw mulch is made out of wheat, and oftentimes wheat seeds will germinate in the mulch, thus you might end up with some wheat in your mulch. I don’t really consider this to be a big disadvantage of mulching as no matter what you do you will get the occasional weed.
Mulches Can Dry Out The Soil
Inorganic mulches like rubber, plastic and decorative pebbles will dry out the soil beneath them. These mulches are excellent at keeping out weeds but most of them create a miny greenhouse effect, which will end up drying out the soil. If you have ever used plastic mulch then you already know how hot these can become, and no amount of watering will help the situation. As the inorganic mulch heats up it will start to heat up the soil and the plants as well, which can end up in disaster.
So if you are planning to use permaculture or a sustainable homestead by growing your own food, then do not use plastic mulch as in the long term you will destroy the topsoil.
You Can Not Grow Plants From Seeds In Mulch
If you want to grow plants from seeds then you have to remove the mulch, as most seeds will not be able to grow through the mulch. Plant the seeds directly into the ground and let them establish their first true leaves, once they are established you can mulch around them. Some seeds will germinate in mulch, although most seeds do not actually have the required energy to pierce through the mulch. If you want to know what plants can grow through mulch the check out my recent article Will Plants Grow Through Mulch? ( Organic And Inorganic Mulches ).
As you can see mulching has a couple of disadvantages, but it mostly depends on what kind of mulch you are using and how you actually using it. Make sure to place the mulch around your plants without the mulch touching their stem, as the mulch can actually damage the plant if it is in direct contact with the stem of the plant.