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Part 1: The Why and Whats of Mulching
More Reasons Than Ever to Mulch
Rich looking, neat as a pin, weed free, and glowing with health - does that sound like the yard or garden of your dreams? It can easily be a reality if you use mulch. Once thought of primarily for vegetable gardens, mulch has come a long way. It's now recognized as an essential ingredient for more beautiful and easier-to-maintain flower beds and landscape plantings of all kinds. And in addition to beautifying your property, mulch has many important environmental benefits as well, one of the most important of which is water conservation.
Our water supply is finite and often unevenly distributed. Some gardeners may experience water shortages and brush fires, while others are building levees and raised beds. Although mulches may not do much to control excess moisture, they are essential in the battle against water loss. They are so important, in fact, that California enacted a bill requiring the use of mulches: the Xeriscape Act of 1989.
Xeriscaping is a garden design principle whose aim is to reduce the amount of water used on landscapes. While the idea of conserving water in the garden has been around for some time, the xeriscape concept was refined by the Denver Water Department in 1981, after a particularly dry summer. The department developed what have become the seven basic principles of xeriscaping: proper planning and design, limited use of turf areas, use of efficient irrigation systems, soil improvements, mulching, use of plants that demand less water, and appropriate maintenance (such as weeding and fertilizing). This concept quickly spread to Florida, Texas, Arizona, and California, where droughts are a fact of life. The National Xeriscaping Council, Inc., has been established in Austin, Texas, to coordinate and promote the xeriscaping movement. After all that, who would need to be convinced to use mulches?
It seems, though, that mulching does require more justification for some. For one thing, mulch doesn't even sound very nice, which may be one strike against it to begin with. In its earliest Middle English sense, the word mulsh was an adjective that meant, according to Mr. Webster, "soft or yielding." That's not so bad. But by the time our language had evolved into what is now called Early Modern English, centuries later, the "s" in mulsh had become a "c," the adjective had become a noun, the word itself had come to mean "rotten hay," and something pleasant was lost in the evolution.
Now this is to suggest neither that rotten hay is necessarily undesirable nor that rotten hay is the only kind of mulch there is. There are many, many kinds of materials that can be used for mulching, as we shall see. The mulch materials you choose for your vegetable garden can be practical, but not necessarily beautiful. On the other hand, you'll find dozens of choices for mulching around your landscape plantings and flower beds where the mulch itself can be an important feature of the overall design. Whatever the choice, to the knowledgeable gardener, mulch can be the most beautiful stuff in the world.
Some vegetable gardeners object to mulching for purely aesthetic reasons. They prefer the traditional look of arrow-straight rows and bare, immaculately cultivated earth. There still are plenty of these "model" gardens around, and that sort of thing is fine if you have lots of time and patience, plenty of water, and maybe a few slave laborers who can help you maintain this kind of elegance. Most of us do not. Let's face it: except for the very affluent, the days of the full-time hired gardener are gone forever. Besides, mulch does not have to be unattractive, as we shall also see.
Because my garden is in a northern section of the United States, I know that what works well for me may not work well for you in your garden. You also should remember that there is no one "right" way and no one "wrong" way to mulch. There are good ways, and there are not-so-good ways. This book offers suggestions about some ways to mulch your gardens to make them happier, healthier, and more rewarding. I will also try to make you aware of certain dangers and pitfalls, but I will never say, "This is the way." That is for you to decide.
Here's Why: The Benefits of Mulching
Mulching has many benefits, not the least of which, as far as I'm concerned, is that you can walk around in your garden on rainy days and not have 3 inches of sticky mud on the soles of your shoes when you come back inside. I choose to ignore the experts' warnings to stay completely out of the garden on wet days. I am careful not to touch anything, mindful that I might be transmitting some harmful bacteria or virus to the plants. And I try to stay in the middle of my mulched path so I don't compact the soil near my plants. But it seems to be a compulsive ritual with me to go into my garden at least once a day. I need to squat down next to a row and gently (sometimes not so gently) try to coax young seedlings into growing faster, bigger, or greener. Not a scientific argument for mulching, I know, but certainly an emotional one.
For mulching's technical benefits, I turned to Dr. Donald Rakow, Professor of Landscape Horticulture at Cornell University. According to Dr. Rakow, mulch's three major benefits are reducing water loss from the soil, suppressing the growth of weeds, and protecting the soil from temperature extremes.
Mulch Retains Moisture
Mulch's ability to conserve soil moisture has long been documented. While authorities and test results differ, it is clear that mulch reduces moisture evaporation from soil by anywhere from 10 to 50 percent. Mulch's water-conserving value can't be overemphasized, especially during times of water restrictions, shortages, and drought conditions.
Mulch keeps soil from drying out partly because it prevents dew and water, drawn up from the subsoil, from escaping. Contrary to what many believe, dew is not only water condensation from the atmosphere; it is also moisture condensation from air pockets in the soil. As far as plant growth is concerned, most dew is completely wasted unless there is something on the surface to catch it and prevent it from evaporating.
Some impervious mulches, like black plastic or old boards, may catch more dew because they don't allow air to pass through. The downside is that they also don't let water or air in. That's something to keep in mind when selecting a type of mulch. More on that later.
Mulch Suppresses Weeds
Mulching can practically eliminate the need for weeding and cultivating. Imagine how much extra time that will leave you for picking strawberries, lying in the hammock, or visiting other gardeners!
There are a few catches, however. First, the mulch itself must be weed free. Many a gardener's best mulching intentions have gone astray with one application of weed-strewn hay or manure. Rather than controlling weeds, they ended up introducing a whole new pesky weed crop.
Second, mulch must be deep enough to prevent existing weed seeds from taking root. Weed seedlings need light to grow. Weeds sprouting under a dark blanket of mulch wither away without light. If mulch is applied too thinly, weeds may still poke through. So when you mulch, be as persistent as a weed and cover all open areas.
Finally, mulches won't smother all weeds. Some particularly tough weeds have the fortitude to push through just about any barrier. In a well-mulched bed, though, these intruders should be easy to spot and even more easily plucked.
Mulch Insulates from Heat and Cold
Mulch's ability to regulate soil temperature is probably one of the benefits most often overlooked, especially by first-time gardeners. Many of us are so concerned with aboveground temperatures that we don't spend much time pondering what's happening underground.
Simply stated, mulch is insulation. It keeps the soil around your plants' roots cooler during hot days and warmer during cool nights.
In winter, mulch works to prevent soil from alternately freezing and thawing, which leads to soil heaving and root damage. Now this doesn't mean the soil won't freeze; it just won't happen overnight. Rapid freeze-thaw changes not only threaten aboveground growth, they also may send tender plant roots into shock. That's why it's best to apply winter mulches in the fall, after a good frost when the plants are dormant. Come spring's warm weather, be sure to remove the mulch when plants start sprouting new growth.
On the other hand, mulches are useful for controlling soil temperatures in summer. These are frequently referred to as "growing" or "cultural" mulches. Applied in the spring after the soil starts to warm up, they stay in place for the majority of the growing season.
Extremely high soil temperatures can inhibit root growth and damage some shallow-rooted plants. During the long, hot days of summer, a mulch can reduce soil temperature by as much as 10 degrees F.
Some plants, though, thrive in heat. Besides organic mulches, there are special synthetic mulches for them. Tomatoes, eggplants, and peppers appreciate high temperatures. Black or red plastic around tomatoes has been shown to increase fruit yields.
You can remove some or all of an organic mulch at the end of the season. Most types are usually incorporated right into the soil -which leads us to some of the other benefits of mulching.