The next time you spot a beautiful garden or landscape in your neighborhood, take a look at the soil below the colorful flowers and healthy green shrubs. Chances are you’ll see that all this attractive growth is supported by one of gardening’s secret weapons: mulch.
A broad term for just about any material applied to the surface of the ground in order to help improve soil conditions, mulch isn’t glamorous by any means. However, as anyone with a green thumb will tell you, it is an essential element of a healthy garden and a high performing landscape design. Here’s what you need to know about this key gardening ingredient.
Mulch benefits your landscape in many ways.
For such a humble material, mulch offers an impressive variety of gardening benefits, including:
Moisture retention—One of the biggest reasons to use mulch in your garden is to prevent the soil below from drying out. A healthy layer of mulch retains moisture and slows water evaporation from the soil, leaving your garden better hydrated (and thus reducing the need for frequent watering).
Insulation—Mulch provides a helpful buffer against temperature extremes, preventing the soil from getting too chilly in cold regions, and protecting plant roots from extreme summer heat.
Weed suppression—Mulch not only helps prevent most weeds from growing in the first place, its loose structure also makes weeds that do gain a foothold easier to pull up.
Prevention of erosion and compaction—Heavy rains can wash away surface soil (erosion) and pummel down remaining soil until it is densely packed (compaction), which can be damaging for plants and their root systems. Fortunately, mulch can protect against both these dangers, keeping soil loose and slowing stormwater runoff.
Disease reduction—When rain splashes up from the surface of the ground onto plant leaves, it can bring harmful, disease-causing organisms with it. Mulch helps prevent disease outbreaks by absorbing water more effectively during rainy weather and preventing splashing.
There are two main categories of mulch.
The many different types of mulch can be divided into two general categories:
Organic mulches—A wide variety of organic materials (usually plant byproducts) can be used as mulch. These organic mulches will decompose over time, thus improving soil fertility, aeration, structure, and drainage by adding extra organic matter and nutrients. For this reason, organic mulches are usually preferred by landscape professionals over inorganic mulches. Hardwood and softwood chips, shredded bark or bark nuggets, pine or wheat straw, evergreen needles, shredded leaves, and grass clippings are all common examples of mulches in this category.
Inorganic mulches—Mulches can also be made of non-organic materials that don’t typically decompose, including human-made substances. These don’t provide all of the benefits that organic mulches do, but they can still be a useful choice in some gardening situations, especially since they don’t usually need to be replenished. Rock, stone, lava rock, pulverized rubber, landscape fabric, and crusher dust are common inorganic mulches that are frequently used for decorative purposes. They can also help control weeds and, in the case of heat-absorbing rock and stone particularly, warm the soil for early spring planting.
Mulch is simple to apply.
One of the best things about mulch is that it is very easy to use. Simply choose your preferred mulch type, and apply it in a layer over garden beds and around plantings. In general, you’ll want to aim for a layer that is two to three inches thick. Spread the mulch all the way beyond the plant’s drip line, or the point around the outer edges of the leaves. Make sure you leave a mulch-free space of two to four inches around tree trunks, shrub stems, and perennial crowns.
If you’re using organic mulch, water it well after you’ve applied it to prevent the mulch from absorbing too much soil moisture. Water will also give lighter mulches some extra weight and prevent them from being blown away by the wind.
You can use mulch in just about any area of your garden.
If you’re wondering where in your garden you should apply mulch, the answer is: just about anywhere! For example, you can use mulch around:
Perennials and annuals—Flowering annuals and perennials will benefit from a two-inch layer of mulch applied at the start of the growing season. Make sure you replenish the bed as the mulch decomposes.
Roses—Roses are well known for being thirsty, so using an extra thick layer of mulch (four inches) around the base of rose bushes can help keep the soil nice and moist. Just be sure to leave enough space around the base of each plant.
Vegetables—The weed-suppressing power of mulch is a great advantage for vegetable gardeners. If you’re using raised or in-ground beds, spread a layer of mulch—materials like straw or grass clippings work best here—between rows of seedlings to discourage weeds from popping up and crowding out your growing veggies.