I moved into a townehouse cooperative nearly two decades ago. One of first things I learned about gardening was the importance of using mulch to protect the soil and keep the weeds down. Thus began my gardening passion. Over the years I have read hundreds of gardening books. I learned some important things about the link between good soil and the use of mulch over my garden beds.

Every shovel full of soil has hundreds if not thousands of dormant weed seeds just waiting for the proper amount of moisture or exposure to the sun to trigger germination. I learned that mulch is essential because it helps to deprive those weed seeds of the light they need to germinate, thus reducing the hours I spend weeding. I also learned that keeping a layer of mulch over the soil between plants helps keep the soil moist even in hot and dry weather conditions. Obviously, mulch is important as a means of keeping the garden weed-free and reducing water use.

Mulches may be either organic (material from living things) or inorganic (rock or minerals). Each type has its purpose in your garden. Let's take a look at samples of each type.

Organic Mulches

Over the past fifteen years, I've learned that organic mulches feed the living organisms in the soil. While digging my first garden bed, I was surprised that I found no earthworms. The bed was almost total clay. Earthworms help to aerate the soil by their movements through it. They also drop bits of food (organic matter) due to their notoriously messy eating habits. This organic matter feeds microscopic organisms. Scientists are still learning just how important those microscopic organisms are to the health of plants. These organisms help release nutrients that are used by the plants.

Shredded Bark. You can buy bags of bark which have been shredded. The size of the mulch pieces can range from small to very large. Either softwood (pines, evergreens) or hardwood (oak, maple, etc.) may be used. The softwood mulch breaks down much faster than hardwood mulch. I use softwood mulch and replace it each season. Much of the mulch is broken down by weathering and earthworms over the year. This feeds the earthworms that transport pieces of the mulch throughout the soil.

Chopped Leaves. Every fall my perennial garden is put to bed with a 4-6 inch layer of chopped leaves. The earthworms work throughout the winter processing this mulch. If necessary, these leaves are covered with a layer of shredded bark in the spring. My goal is to leave no exposed soil during the gardening season for reasons discussed above.

Some people use grass clippings or straw. Both of these mulches have the potential of causing problems in your garden. It is essential that neither has been treated with herbicides just prior to being used in the garden. They both have the potential of introducing weed seeds to your garden. Be sure you know the grass or straw is from weed-free fields before spreading them on your garden or you may create a major problem for yourself.

I've known people that used aged manure, chopped corncobs, and various other organic materials. If you like these ideas, look around your area for an inexpensive source. Personally, I only like the looks of shredded bark or leaves. These are also easily attainable for me.