Understanding the Benefits of Garden Mulch

By Steven A. Frowine and The National Gardening Association from Gardening Basics For Dummies

Using mulch is a good gardening habit but not mandatory; the benefits, however, make it worth the effort. A really good job of mulching your garden usually offers these benefits:

Inhibits weed germination and growth. (Weeds are not only unsightly, but they also steal resources from desirable garden plants!)

Holds in soil moisture, protecting your plants from drying out quickly

Moderates soil-temperature fluctuations (This benefit is especially valuable during that turbulent-weather period in spring when you don't want your plants to be stressed.)

In cold-winter areas, protects plant roots from winter cold and helps prevent frost-heaving, in which plants are literally pushed out of the ground by the natural expansion and contraction of the soil as it cools off and heats up

In hot-summer areas, helps keep plant roots cooler

Depending on what you use, adds a bit of welcome nutrition to your garden as it breaks down

The "right" or "best" mulch to use depends on your climate, the part of the country you're in, and the part of the yard you're using it in. Some mulches are free, while you can purchase others locally. Experiment to find out what you and your plants prefer.

Table 1 provides the basic information you need to know about some of the more popular options.

Table 1: Comparing Mulching Options

*Type of Mulch*	*Advantages*	*Concerns*
Grass clippings	Is cheap, readily available, and easy to apply	Decays quickly, so you must replenish often. If you use weed killers on your lawn or nitrogen-heavy fertilizer, it may adversely affect other parts of the garden; can turn slimy if you apply more than an inch or so at a time; if the grass goes to seed before you cut it, the grass seeds can germinate in your garden beds (yikes!)
Wood or bark chips	Looks neat and attractive; stays where you put it; is slow to decay	Pine bark mulch is fairly acidic, which you may or may not want for your garden; if you apply too deeply (over 3") or apply a deep layer up against tree and shrub trunks, you may create a hiding spot for a bark-damaging rodent, especially during winter
Decaying leaves	Smothers weeds very well; helps hold in soil moisture	Is not especially attractive; if it contains seeds, they can germinate and become a weed problem; if the leaves are soft, like maple leaves, the mulch can mat; if it's acidic (oak especially), it can lower your garden soil's pH
Compost	Is free and plentiful if you have your own compost pile; adds nutrients to the soil as it breaks down	Makes a good place for weeds to take hold; fresh compost (especially if it contains manure or grass clippings) can burn plants
Peat moss	Looks neat and tidy; is versatile — also functions as a soil amendment	Can be expensive; if dry, will repel water; becomes crusty over time
Straw	Is cheap and easy to apply	Is so light it can blow or drift away; may harbor rodents, especially over the winter months; isn't very attractive for ornamental plantings
Hay	Is cheap and easy to apply	May harbor rodents, especially over the winter months; isn't very attractive for ornamental plantings; probably contains weed seeds!
Gravel, pebbles, or stone	Has a nice, neat look (though not "natural"); is easy to apply; won't wash away easily and will last a long time; doesn't need to be replenished over the course of a season in colder climates	Can allow weeds to sneak through; provides no benefits to the soil
Landscape fabric (garden plastic, black plastic)	Keeps weeds at bay; holds soil moisture and warmth in	Watering and feeding is hard (you need to cut openings for plants); can be difficult to apply unless you're doing an entire area at one time; isn't very attractive
Rubber (shredded recycled car tires)	Very long lasting, available in many colors, looks like shredded wood mulch	Can smell strongly of rubber; provides no nutritional benefits to the soil