Mulching is an essential practice for gardeners of all levels. It can help retain soil moisture as well as preserve the temperature of the soil, protecting plants from excessive heat or cold. However, many gardeners can get confused as to whether or not they can put new mulch over old mulch. This is why I’ve written this blog post to explain whether or not this is possible.

Most gardeners agree that it is possible, and even recommended, to put new mulch over old mulch. Mulch gradually breaks down over time and can help provide essential nutrients as well as other organic matter to your soil. Removing mulch that has yet to fully break down can be exhausting and time-consuming and can also be costly, as you would have to replace it with new mulch.

However, there are other factors that you should consider before deciding whether or not to put new mulch over your old mulch. This can include various factors such as the type of mulch you are using, as well as how recent weather conditions have been.

Is It Possible To Put New Mulch Over Old Mulch?

A mulch is simply a layer of material placed over the surface of the soil. This is usually done to help save water, suppress weeds, as well as improve the condition of the soil in your garden by preserving temperature and moisture.

Mulching tends to be done annually. And one of the most common questions asked is whether or not we should remove old mulch from the previous year before applying new mulch for the coming year or simply apply a new layer of mulch on top of the old layer.

Most gardeners tend to agree that getting rid of old mulch is unnecessary. This is because decomposing mulch tends to add beneficial nutrients as well as other compounds that can be helpful to the growth of one’s plants. 

However, during the year your plants may have experienced some form of disease. When this happens, you may have been able to trace the source of the disease to your mulch. In this scenario, the best course of action is to remove the old mulch completely to prevent the same disease from coming back.

Also, one should take into consideration the current state of their old mulch. Remember that the main benefit of laying new mulch over old mulch is that old mulch can decompose to provide essential nutrients to the soil. In other words, the only old mulch you want to keep is those that have not yet decomposed completely throughout the year.

One good way to tell whether or not the old mulch has decomposed completely is to pick it up and carefully roll it around in your hands. If the old mulch consists mainly of small particles that are the same as dirt, then it has likely completely decomposed and will not provide much more value to your soil. You may want to consider replacing them with new mulch.

All mulch will eventually decompose. But some types of mulches tend to decompose less rapidly than others. These include mulches made from tree bark as well as shredded hardwood. These types of mulches can end up knitting together and forming matted mulch which can stop water from soaking into the soil as well as prevent sunlight from reaching the soil and warming it up.

I’ll talk more about matted mulches and how to prevent them later on.

When Is The Best Time To Apply New Mulch?

Mulches are generally best applied during spring, when most weeds have yet to germinate and other plants lay dormant. During spring, the soil also begins to warm up from the colder winter temperatures.

As mulching is typically done to retain the temperature of the soil, one should avoid mulching too early (i.e. when the soil is still cold) as this can slow down the warming process that is key to making the soil compatible with your plants. Mid-to-late spring is generally around the time when your soil starts to get warm enough for you to start mulching.

Some gardeners also choose to mulch in the autumn when plants begin dying. Mulching in autumn has the added advantage of allowing your soil to retain the heat that is gathered during the summer season. However, one should be aware that mulching in the autumn can prevent plant dormancy, which is essential for helping your plants survive the coming winter.

The timings for mulching can also vary depending on the type of plants you’re growing. Different plants usually require different timings in order to get the best results. For example, perennial plants such as lavender are best mulched when they are completely dormant.

Because perennials tend to break their dormancy in spring, this might not be the best time for you to start mulching if your garden has a lot of perennials.

Understanding exactly what types of plants you’re growing and what the best timings for mulching are for them can help you get an idea for when you should start mulching.

How Do I Loosen Up Matted Mulch?

Some forms of mulch are prone to slow decomposition. Examples include shredded hardwood as well as chips of wood.

These are preferred by some gardeners over quickly decomposing mulches due to their ability to resist strong winds and rain. Mulches can be expensive, and the last thing you want is to have them blow away during harsh weather conditions. These types of mulches also look attractive and can work wonders to increase the aesthetic look of your garden.

However, one common problem with slowly decomposing mulches is their tendency to compact into matted mulches over time, blocking essential air and water from reaching the soil and hence the roots of your plant. Sometimes, matted soil can also stop sunlight from warming the soil which can harm the growth of your plants.

A gardener can stop this from happening by loosening up matted mulches before they start to have a negative impact. Most gardeners tend to do this at the same time as applying new mulches.

You can use a pitchfork (or garden rake) to flip the mulch in the air and turn it over multiple times to loosen it up. Take care to avoid applying too much force as this can cause your tool to penetrate the soil and harm the roots of your plants. It may be preferable to move any matted mulches away from any plants using a wheelbarrow before loosening them.

Once complete, add in any new mulches if necessary and reapply the mulch over your garden. Don’t forget to water the newly spread mulch to help it settle into place.

Conclusion

Annual mulching is essential to the long-term health of your garden. Mulches can suppress weeds, conserve soil temperature and moisture, and also contribute valuable nutrients to the soil. Mulches done properly can also play a role in making one’s garden look aesthetically pleasing.

Putting new mulch over old mulch is often recommended by many gardeners because decomposed mulches tend to be good for the soil. However, there might be some cases where you don’t want to lay new mulch over old mulch, such as when a disease has occurred that can be linked to your old mulch, or when your old mulch has already completely decomposed.

Knowing when it is the most appropriate time for you to begin mulching can help you get the best results from your gardening.