It is so easy to overlook what makes a good mulch because mulch is so commonly used and bad ones are easily found at any gardening store. However, taking just a few minutes to find a good mulch can have a big impact on your soil’s health this year and for many years to come.
Mulch is a layer of material that covers soil and our blog post, Why should I use mulch?, covered the benefits that mulch provides.
The first criteria for a good mulch is that it should provide as many of the mulch benefits as possible. Second, since there are a variety of good mulch options available, we want our mulch to come from a sustainable source so that we improve our garden and local community, together.
We’ve grouped the various types of mulches into two lists, basically good and bad.
Avoid these mulches:
In general, these mulches introduce bad things to your garden and aren’t sustainable. Since we have so many good options in our greater-Prince William County area, it’s generally better to avoid these types of mulch all together.
Dyed mulch: We’re not a fan of dyed mulch. It is so misunderstood that we wrote a blog post about it.
Plastic sheeting (and landscape fabric): This doesn’t break down to help our soil and isn’t sustainable—we should be reducing our reliance on plastic. Additionally, like landscape fabric, it limits or stops beneficial critters from taking the organic matter that’s made on top of the soil (e.g. from decomposing mulch) down to plant roots.
Rubber (plastic) mulch: These are petroleum-based and don’t belong in a garden. Especially with our hot summer sun, they can break down over time and introduce chemicals into your soil and our local community. While these are “recycled,” there are other good homes for them.
Hay: (Not straw) Hay comes from grass crops—we have a lot of fescue and bluegrass in the area—and there are two concerns with using this. First, hay will likely contain seeds and so you’ll start growing grass in your garden if you use this as a mulch (but it's a good a good option when covering grass seed!). Second, and perhaps more importantly, the grass may have been treated with a weed killer—they have herbicides that target broad leafed weeds (and plants)—and putting herbicide-treated hay as a mulch on your plant beds can hurt your soil. Once the damage to your soil is done, it can take a long time to work its way out of your soil.
As an aside, this herbicide can also be in horse manure (what's one of the things that horses eat?...). Thus, if ever using manure as a compost, be extra careful to know its source!
Stones, gravel, shells: They don’t break down so fail to provide one important benefit—improving the soil underneath! Since there are better options for most settings—like a courser wood mulch for heavy walkways—and mulches that provide more benefits, this makes the ‘mulches to avoid category’ but also isn’t the worst of the group.
The best mulches
These mulches add a lot of value to your gardens, are sustainable, and in some cases, free! This is a win for your wallet, garden, and the environment.
Ground cover / “living mulch”: Cover crops and ground plants are considered living mulches since they protect the soil surface, reduce weeds, and their roots provide incredible benefits for your soil. This is an amazing (and underutilized!) option.
Shredded leaves: Shredded leaves may be one of the cheapest, easiest and best mulch options for your garden. Simply run over the dead leaves with a mower to cut them up. The ground leaves can be applied as a garden bed mulch right away, or you can let them break down in a pile over the winter. When leaf mulch is applied in the spring, it lasts for the gardening season and breaks down just in time for a fall compost application (so you don’t have any mulch removal step).
Grass clippings: These are free, great for your garden, easy to spread, and only require a little work to make them. Just make sure to dry your grass clippings in the sum—they should be a little crispy when done—before you use them as a garden mulch. Wet grass clippings can generate heat and mold for your soil, so best to lay them out to dry first.
If you don’t currently use grass clippings as a mulch on your lawn (grasscycling), this is a great way to add some or all of the nitrogen and organic matter that your lawn needs to grow and stay green. Personally, I think this is a better option than using them as a garden mulch since it saves time and money.
Natural wood mulch (not dyed): There are number of different natural wood mulches—they vary by type of wood (e.g. pine, cedar, hardwood, softwood) and processing techniques (e.g. chips, double shredded, triple shredded)—and all of them, if they are well made, can be a good option for your garden. We’ll do another blog post in the future on the differences in natural wood mulches and have a buying guide to help you find the option that’s best for your garden.
Straw: Straw is easy to work with, plentiful in our area, and looks good. All-in-all, this is a good mulch option.
There are so many great (and sometimes free!) mulches in our yard and area. And, because these mulches are natural and sustainable, it helps our garden and community grow good, together.
We make premium and local compost, mulch, and topsoil in Manassas, VA. They are specially designed to increase the health and productivity of our local soils, and with our focus on sustainable practices, this lets the environment and your garden grow good, together. We sell bulk and bagged compost, bulk natural mulches, bulk and bagged dyed mulches, and bulk topsoil.