There are a lot of mulches readily available for the vegetable garden. Most common mulch options are easily sourced from your own yard, the neighbors lawn, or from town maintenance crews. With so many choices, it's confusing to know which is the best choice for your vegetable garden. Each mulch type has potential benefits and drawbacks, and its important to know about them before choosing the right one for your garden. Many gardeners use a combination of mulches, to maximize the benefits of each one.
There is so much to love to about leaves as a mulch. First of all, they're free. Second, leaves are widely available every fall; ask around to your friends and neighbors – everyone has leaves! Most people rake them up and send them off in yard waste bags to the landfill, but that is a huge waste of a valuable material. Plus, it needlessly clogs up the landfills. Sourcing leaves for mulch is easy, there's no lack of supply, and it's usually the least expensive option.
Leaf mulch is an excellent weed blocker, though not quite as efficient as wood chips or straw. Leaves decompose readily, adding essential micronutrients into the soil every year. This type of mulch is best used over whole garden beds and around plants. Because they break down so easily, leaves are not the best choice for paths or walkways. Plus, when it rains, they can get quite slippery!
Leaves must be shredded or broken down before being applied to the garden. Whole leaves are actually quite bad for the vegetable garden because they clump together, forming dense impenetrable mats. These leaf mats prevent water from reaching the soil and can harbor bacteria and fungus which is harmful to your plants. Shred the leaves with a lawn mower or mulching mower. Leaf mulch is easily overwintered in piles so it will be ready and available for the spring garden.
If you live in a windy area, leaf mulch may not be the best option, since it gets blown away easily. Putting a thin layer of wood chips on top of the leaf mulch helps prevent this, but not entirely.
Wood chips come in many shapes, sizes, and types. Hardwood mulch lasts a long time, while soft wood mulch, or finely ground wood mulch, usually breaks down over a season. For paths and walkways, hardwood mulch is a clear winner. It looks fantastic, too! Softwood and finely ground wood mulch is better for layering in-between rows, or as a weight on top of leaf mulch.
Local tree service companies are often an excellent source for free wood chips. Usually, the companies have to haul it away themselves or pay to take it to a landfill, so they are happy to let you have it. Many town yards have wood chips available, as well, from routine tree trimming. Also, lumberyards always have woodchips as a byproduct of their operations and are happy to let you have them. Lumberyards usually incinerate their waste, so you taking some of it beforehand means a little less work for them.
Important Note: Always ask about the source of the wood chips. Sometimes companies break down decks, old playgrounds, or pallets that have been treated with chemicals or insecticides and this is combined with other wood mulch. You don't want those things in your vegetable garden, so be sure you know the source before taking it. Store-bought wood chips also have this potential issue, and it is difficult to know exactly what you're getting. Packaged wood chips are often also treated with a dye to give a uniform color. The dye isn't as much the issue (usually it's vegetable based) as what it is covering up.
There is a common misconception that wood chips rob your soil of nitrogen; this isn't true as long as the chips are applied as mulch on top of the soil. If the wood chips are mixed into the soil, increasing the contact surface of soil to wood chip, then it can be a problem.
Never use wood chips from black walnut trees. These trees contain a natural chemical called juglone which may inhibit the growth of your vegetables. Juglone will break down after 8-12 months, so if you suspect the chips include black walnut, let them age before using them in the garden.
Farms, garden centers, and home improvement stores usually carry straw and hay. It's best to get straw – this is the grass or grain stalk that doesn't contain any seed heads. Hay will have seed heads, which become weeds in the vegetable garden. Also, hay is often treated with herbicide, which can then be introduced to your garden with disastrous results.
Straw takes longer to break down in the garden, but still is usually completely broken down in 1-2 years. It is excellent for mulching around vegetables, and between rows.
Another amazing and free material, grass clippings make excellent mulch. The clippings need to be dried before being applied to the garden, so as not to grow mold or spread seeds. If you don't have a large yard, ask your neighbors for their clippings; just make sure beforehand they don't treat their lawn with any chemicals or insecticides. Grass clippings are ideal mulch around individual plants and between plant rows. It holds up the entire season and decomposes by the following spring, adding tons of good organic material into the soil. Also, using grass clippings is an awesome way to re-purpose waste that you would have to get rid of some other way.
If you have more than one of these options available to you, try them all out. You may find you like working with one type of mulch better than another. A lot of the choice revolves around availability and personal preference. They all get the job done. Many gardeners, including myself, use all of the types in different combinations. The next article in this series about mulching will discuss how to apply mulch, including determining where the best places are to use the different types.