Mulching is a wonderful, but underutilized, garden practice. It is low tech but high impact. And it's cheap. Mulch suppresses weeds, conserves soil moisture, prevents erosion, moderates soil temperature, and adds organic matter to the soil. Proper mulching also reduces soilborne plant diseases by preventing rain or irrigation water from splashing up onto the plant foliage, and it simply makes your garden look better :)
There is an art to mulching and the first step is deciding what to use. The best way to start is to use what you have on hand. For most gardeners, leaves and lawn clippings are readily available.
Grass clippings are easily available every time you mow your lawn. Simply hook up your bagging attachment to your lawn mower and you are good to go! When using fresh grass clippings, limit the layers around your crops to about 1/2 inch thick or the clippings may begin to decay anaerobically from the center of the layer, leading to too much heat and bad smells. A thin layer breaks down quickly and adds nitrogen to the soil as well as the ever important organic matter. You can also let the clippings age and dry out some before spreading them. The biggest drawback to using grass clippings is weed seeds.
Shredded leaves are an excellent mulch for summer because they protect the soil so well against the heat of summer sun. An area with a 4-inch layer of shredded leave mulch can be as much as 10F cooler than bare soil would be. It's easy to shred leaves, again using your lawnmower. Spread the leaves over a patch of your lawn and set the mower height for at least 3 inches. Mow over the leaves from the outside in until they are as finely chopped as you want them. Next put on your lawnmower's bag attachment and use the mower to suck up the leaves. You can store the mulch in piles around your garden, using it as you need to. This also makes a great compost to add to your soil at the end of the season when you are tilling your beds and putting them to sleep for the winter.
Mulches can also be organic matter such as shredded bark, compost, pine straw, wood chips. Straw is a great summer time mulch when you want to buffer the soil against the summer heat. Soil covered with a 4-inch layer of straw stays as much as 8F cooler than unmulched soil. And in most parts of Texas at least, straw is cheap. I get mine at my local tack/feed store for about $7 bale.
As some of you know, I use cedar bark mulch on my garden and it works great. We acquired all this fabulous mulch when we had a bunch of cedar cleared from our property a few years ago. As part of the process, we had the landscapers chip the cedar bark into fine pieces and just had them rake it into big piles. I keep several large piles by my garden and use it for mulching my vegetables/plants/citrus trees, adding it as organic matter to the soil in my beds, and weed control on the ground around my garden. Like I've said before, I love this stuff!
When planting seeds in vegetable gardens, it's best to mulch after the seedlings have emerged. But for my winter seeds of beets, romaine, broccoli raab and chard, I covered each row with a very thin layer of straw to help stop radiating heat loss in the soil. The little seedlings can still poke up through the straw. As a general rule, 2-3 inches of organic mulch applied to the soil surface is adequate.
What type of mulch you use is usually determined by where you live. Whatever is in the local nurseries for mulch, is what is likely to work best in your area. And it's always best to buy bagged mulch over mulch in bulk. Bulk mulch may be a little cheaper but it is *so* much more work! Think of all the shoveling and hauling you'll have to do to get the mulch where you want it. The significant amount of additional work may prompt you to say..."the heck with this mulch thing!" which would not be a good thing for your garden. Bagged mulch is easier and you are more likely to stick with it.
Mulching is a simple, effective way to protect your plants, add organic matter to your soil, maintain soil moisture and help keep the weed population down. I can't imagine gardening without it.