When determining what mulch is best for your vegetable garden, you may encounter all manner of solutions online and suggestions from fellow gardeners. But what mulch works the best for growing big tasty veggies while keeping the weeds down. Following are some of the most common mulches used in the vegetable garden listing their pros, cons, and where they are best suited for use in the landscape. For a material to perform successfully as a mulch it should suppress weeds, allow good water and air exchange from the atmosphere to the soil, and offer long-term contributions to soil health.
Shredded wood mulch
By far the most popular type of covering, shredded wood mulch can be easily found at any garden center. What I like about shredded wood mulch is the uniformity of the pieces and how they can knit together to hold in place. The double-edged sword with this is the mulch can form a “shell” over time, limiting water and air exchange in the soil. Cultivate your shredded wood mulch at least once a year. Shredded wood mulch also decomposes over time to add nutrients to the soil. (As do all the other wood-based mulches I’m about to mention.) A problem fungus known as artillery fungus can inhabit wood mulch. Why the hawkish name? Artillery refers to the tiny black spores fired by the fungus in the mulch, which sticks to everything, siding, fencing, car paint. (The artillery fungus issue also applies to all the following wood-based mulches.)
Dense wood-based products will take a long time to break down, so placement in vegetable garden beds is not always recommended. Often the mulch will need to be moved aside when seeding rows. This is the case with all the wood-based mulches mentioned afterward.
One final drawback is that shredded wood mulch is often made from trees harvested simply to shred and toss on our landscapes. It seems somewhat tragic to cut a tree down, shred it, then scatter its remains to mulch around an invasive ornamental pear tree.
Pros: Readily available, uniform in appearance
Cons: Can be sourced from perfectly good trees cut down to spread on your landscape beds; knits together to form a shell; shredded cypress is hydrophobic (repels water)
Uses: Landscape beds; vegetable garden walkways
Arborist wood chips
From a sustainability standpoint, this is one of the better wood-based mulches. Arborist wood chips are byproducts of the day-to-day tasks of arborists or municipal tree crews and many are looking for a free place to get rid of this stuff. In my town, and many other places, these are free to haul away from the municipal yard waste site. All you need is a truck.
It is not uncommon for wood chips to be taken back to the tree care company’s facility and burned. A gardener can coordinate with a tree care company to take the wood chips off their hands and turn a waste product into a resource. Some more populated areas use programs to organize wood chip donations. There is even an online service to assist with this called ChipDrop.
Arborist wood chips are not as uniform as commercial mulches and may include shredded vegetation. Leaf material from a horticultural standpoint is a good thing as it contributes to the decomposition of the mulch to add nutrients to the soil. The tree may have been cut down because it was diseased or harboring some invasive insect, which may have survived the chipping process. However, this is often a non-issue, but potential disease or invasive species spread should be considered on a case-by-case basis. Feel free to contact your local Extension office or state university plant clinic for specific questions.
Pros: Often can be free; the coarse texture allows water and air movement into the soil; great reuse for what may be considered waste
Cons: The wood chips aren’t uniform; sometimes larger logs get tossed in with the wood chips;
Uses: Landscape beds; walkways in vegetable gardens, landscapes, or even trails in natural areas; vegetable beds
Shredded Fall Leaves
In the struggle to source wood chips in my rural area, I often turn to shredded fall leaves in my landscape beds as my mulch of choice. Fall leaves are plentiful in the Midwest and often underutilized. And usually by the time the summer ends I need more leaves. Fortunately, the deciduous trees in my backyard are happy to supply. Apply caution to trees that had a serious foliar disease. The inoculum for the next year can reside in leaves overwinter. Research has shown in apple orchards shredding the leaves helps reduce the apple scab disease occurrence the following year.
Pros: Plentiful in areas that have deciduous trees; can be shredded to reduce particle size and overall volume; whole leaves can mat down but still useful if your goal is smothering weeds; can be bagged in fall to be used in spring
Cons: Wind seems to move whole leaves more than shredded; not as uniform; possible disease inoculum
Uses: Landscape beds; vegetable garden beds; compost piles/bins; mulched into the lawn with a mulching mower
As a mulch, newspaper ranks poorly. However, it can work as a barrier to suppressing weeds. It is important not to go overboard as laying newsprint too thickly can impede water and airflow into the soil. Typically, I would go no more than six sheets thick of newsprint. Be sure to avoid any glossy paper. The newspaper strategy still requires a layer of mulch over top to secure it in place. One tip if using newspaper is to wet it before attempting to place it down. The slightest breezes can carry away all your hard work.
Pros: A reuse of common household waste (That is if you’re not already recycling it); often free; will decompose
Cons: Still requires a top layer of mulch like woodchips or straw to hold in place; can be laid too thickly; blows around during installation; getting harder to come by as more people are no longer getting a physical newspaper
Uses: A mulch underlayment to suppress weeds; landscape beds; walkways
Perhaps one of the most popular mulches to use in the vegetable garden, straw has many of the same useful qualities as pine needles. As long as the flakes of straw are shaken and spread properly, it will avoid matting down and promote water and airflow into the soil, while still suppressing weed growth. It may be based on geography, but there are times when straw can be difficult to find. Often straw bales will appear in the fall for decorative purposes. They can be stored overwinter for use in the spring garden. I’ve also noted an increasing difficulty of finding straw without seed heads. Good straw will have the seed heads removed and just be the stalks of the harvested cereal plants. Lately, I have been pulling out handfuls of oats and wheat from my vegetable gardens where straw was used.
Pros: Adds organic matter; good water and airflow into the soil; doesn’t compact
Cons: Will blow around; weed seeds
Uses: Vegetable garden beds; light mulching on newly seeded lawns
Depending on your setting, grass clipping might be readily available. More often I recommend grass clippings should be mulched back into the lawn, but if you bag clippings or have an abundance of clippings they can be used in the vegetable garden. The kicker is, the clippings need to be dried before placing them on the garden. Wet lawn clippings can mat down and form a smelly (anaerobic) pile of rotten material. If you intend to use your clippings on the vegetable garden, it is best to avoid lawn herbicides as these can carry over and affect vegetable crops. The drawback to that is you’ll likely have a lawn like mine - full of weeds! (I’d argue, not a bad thing) Those weed seeds will get collected along with the turf clippings and spread on your garden.
Pros: Most gardens have a lawn nearby that requires mowing; available most of the growing season
Cons: Lots of extra labor to collect, dry, and spread clippings; weed seeds; herbicide carryover from treated lawns
Uses: Vegetable garden beds; mulched back into the lawn; mixed into compost bins
Used more for commercial production of fruits and vegetables, black plastic is a plastic film installed on top of the soil and pinned down or buried at the edges to hold it in place. Holes are burned/cut in the plastic to allow transplants to be planted. Humans have a bit of an addiction problem when it comes to plastic and personally, I try to limit my use of it as much as possible in the landscape. However, black plastic does function as mulch suppressing weeds through its sheer impenetrable nature. Often black plastic necessitates the use of a drip irrigation system installed beneath to supply enough water to the plant roots on hot summer days. Plastic should never be used as an underlayment for landscape beds.
Pros: Relatively cheap; easy to install; depending on quality can be reused; suppresses weeds
Cons: Can create hostile soil conditions; yet another plastic product introduced to the environment
Uses: Mulch layer for vegetable gardens
Landscape fabric/geotextile fabric
You have likely seen this material installed as an underlayment for a layer of mulch. Landscape fabrics are made from plastic, but they are woven strips or spun polyester fibers, which makes them porous. Water and air can pass through this material, for a time. Eventually, the landscape fabric will begin to clog with fine sediments, and any weed-suppressing value is gone as unwanted plants will begin growing on top of or right through the fabric. The value of landscape fabric is not as an underlayment, but as a temporary covering in vegetable beds. Landscape fabric can be used much like black plastic, installed on vegetable garden beds with holes cut in it for our crops to grow. However, in the vegetable, we are not installing a mulch overtop the fabric. Landscape fabric also works well as a fairly cheap and quick method for covering walkways in the vegetable garden.
Geotextiles are near identical to landscape fabrics but are often used in the construction of hardscaping like patios or retaining walls. An important use for vegetable gardens is installing geotextile fabric as a barrier to contaminated soils when building raised beds.
Pros: Can be temporary; porous; inexpensive (depending on the grade); Easy to install
Cons: Often becomes more of a problem than benefit when used underneath a mulch layer; cutting or burning holes in the fabric often leads to frays and ragged edges to the holes; more plastic!
Uses: Works well as a seasonal covering in the vegetable garden; garden walkways
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MEET THE AUTHOR
Chris Enroth is a horticulture educator with University of Illinois Extension, serving Henderson, McDonough, Knox, and Warren counties since 2012. Chris provides horticulture programming with an emphasis on the home gardener, landscape maintenance personnel, and commercial landscapers. Additional responsibilities include coordinating local county Master Gardener and Master Naturalist volunteers - providing their training, continuing education, advanced training, seasonal events, and organizing community outreach programs for horticulture and conservation assistance/education. In his spare time, Chris enjoys the outdoors, lounging in the garden among the flowers (weeds to most).