Can You Leave Bags of Mulch in the Rain?

Although mulching might seem like a straightforward process, it’s easy to confuse what works and what doesn’t. And while you need to apply mulch properly to get excellent results, you must store the material well too. So, can you leave bags of mulch in the rain?

You can leave bags of mulch in the rain, but I don’t recommend storing the material in the open. The rain might result in mulch stains on grass and concrete, as well as leaching. However, it might also be hard to dry the mulch properly afterward—leading to anaerobic decomposition.

In this article, I’ll go into even more detail about what happens when you leave mulch in the rain and explore whether wet mulch is bad. However, keep reading to learn if you can use wet bags of mulch in your garden or driveway and whether it’s fine to apply mulch in the rain. Let’s get started!

Effects of Rainwater on Mulch Materials

Whether you get your mulch from stores or prefer to reuse materials from other processes, you’ll still need to store the mulch somehow. After all, it’s unlikely that you’ll use up all your mulch supply in one go.

Still, storage can be slightly problematic—whether you’re a newbie or a veteran gardener. Most gardeners usually opt for sheds and barns for long-term safekeeping.

However, what about the short term?

Short-term mulch storage typically refers to periods under a week, sometimes even days. And while some gardens and farms might have sheds specially built for this purpose, most do not.

Therefore, it’s commonplace for gardeners to leave their mulch out in the open if they plan to use it soon. Of course, this decision exposes the mulch to the elements, including rain.

Rain typically tends to soak through the stuff that most mulch is made of—soft, organic materials. These materials absorb moisture pretty quickly, and the bags that most mulch comes in are rarely ever waterproof.

The moisture typically soaks through the entire bag—or pile—after a few minutes of rain, resulting in streaks and stains since mulch usually has some coloring in it.

These stains might be especially problematic if you keep the mulch on concrete, but they can also be unsavory on soil and grass. However, these stains are mostly harmless since they’re usually the natural dyes present in the organic materials in the mulch.

Still, stains aren’t the only thing you need to look out for if you leave bags of mulch in the rain. There’s also leaching. Like the dyes in the mulch, leaching doesn’t affect your soil in any way.

In fact, it could be beneficial to your garden since it’s the washing away of valuable substances present in the mulch. Of course, this process means the mulch will lose some of its benefits afterward.

Ultimately, these might only sometimes happen. After all, stains and leaching from bagged mulch depend on the quality and nature of the bags as well as the mulch.

Still, these are relatively harmless processes that might not affect the quality of your mulch in the long or short term.

Is Wet Mulch Bad?

The most common question most gardeners ask me is usually centered around the quality of mulch after it’s been exposed to moisture, notably rain. This question is typically a variation of “Is wet mulch bad?”

The short answer is no—wet mulch isn’t bad, spoilt, or even rotten. It’s just wet.

However, this drenched mulch might have lost some beneficial qualities due to leaching, and it might not be as effective as when it was dry. Still, you can use the mulch after drying it properly.

Of course, this part is where you need to take great care. Drying mulch might seem straightforward, but you might lose significant amounts of material to fungal attack if you don’t do it well.

Therefore, you should open the mulch and spread it on tarps to ensure the material dries evenly and thoroughly.

Can You Use Wet Mulch?

Another question I’ve noticed from gardeners and farmers is usually centered around mulch’s usability when it’s wet. And now that we’ve established that wet mulch isn’t bad, it’s essential to know if it’s usable mulch.

As I mentioned, wet mulch is good—it might just be hard to dry and store afterward. However, you can use the still-wet mulch in your garden without hassle.

The mulch should work as it typically would, but you might have some issues spreading it. After all, water tends to make materials heavier. However, you can manage this problem by using the right tools and carrying as much material as possible during the process.

Still, I’ve found that wet mulch is usually easier to spread in specific areas than dry material. In the end, you should try it out to see if you prefer laying your mulch when it’s wet or after it’s dry.

Of course, you’ll need to correctly spread the mulch in your garden to benefit from the practice. 

How to Store Wet Bags of Mulch

An essential part of mulching is knowing how best to store the material—mainly when wet. And although I already mentioned some tips for storage in earlier sections of this article, I’d like to highlight the steps for storing wet mulch.

This process is beneficial if you’re living in a region with lots of rain or need an excellent method to keep some wet leftover mulch.

Here’s how to store wet bags of mulch:

Move Them to an Open Area

Move the wet bags to an open area where you can efficiently work with the material. I recommend a spot with minimal human traffic away from plants or pets. The wet mulch needs sunlight to dry properly, so it’s great if you have an area with little to no shade.

Dump It on a Tarp

Use a sharp knife to cut open the bags of mulch and dump the material on a tarp. You can also pour the material on the ground if you don’t mind cleaning it up afterward. However, I recommend you ensure that the tarp is big enough to hold all the mulch you have before pouring the material.

Spread It Into an Even Layer

Spread the mulch as carefully and thoroughly as possible using a shovel and rake to ensure it dries well. This part of the storage process is vital because it provides breathability during drying. It will also ensure the mulch doesn’t develop mold or mildew afterward.

Let It Dry Fully

Then, leave the material until it’s fully dry. You might need to move the mulch a couple of times while drying, but ensure there’s no anaerobic decomposition throughout the process.

It’s fine if you move the tarp or mulch to a more suitable spot while it’s drying, but ensure most of the mulch is constantly exposed.

Find a Way to Store It

Move the dry mulch to a better spot and store it as you usually would. You can also transfer the dry material to new bags if you prefer storing bags instead of piles. However, you can also keep the mulch in a plastic container.

Ultimately, you’ll need to completely dry the wet mulch if you plan on storing it, regardless of the storage period.

Final Thoughts

Leaving your mulch in the rain might not be bad, but it could lead to stains and leaching. It might also affect the material’s quality and make mulching slightly more stressful. Of course, while storage might seem like a problem, you can easily keep your mulch for as long as possible if you follow the tips I’ve shared.

Alexander Picot

Alexander Picot is the founder of and its lead content writer. He created the website in 2022 as a resource for horticulture lovers and beginners alike, compiling all the gardening tips he discovered over the years. Alex has a passion for caring for plants, turning backyards into feel-good places, and sharing his knowledge with the rest of the world.

Recent Posts