Using mulch in my garden is one of the most important things I do. Why? Because it ties into just about everything I do in the garden. How so?
1- Mulch helps keep the soil moist. The plants, of course, like this. By keeping the soil evenly moist, plant nutrients are more available. Plants grow more evenly, thus producing better quality vegetables.
2- Worms thrive under a nice mulch.
3- Natural soil organisms can do their thing under a layer of mulch, helping to break down organic material, thus providing nutrients. When the sun bakes bare soil, soil organisms die or go dormant.
4- Moist soil stays cooler in my tropical environment, thus better for most plants.
5- Mulch provides food for worms and indigenous micro organisms, thus indirectly, food for the plants.
6- Between crops I rototill the old mulch into the soil, applying a new layer of mulch for the next crop. This keeps the soil loose and airy. I find that plants grow far better in this sort of soil.
7- Mulch conserves water, thus I do not have to irrigate as often. Neither the wind nor sun dries out mulched soil anywhere as quickly as bare soil.
8- Mulched areas do not have a problem with water run off in heavy rain. Mulched soil seems to be able to better absorb rain.
9- Mulch helps control weeds. Without mulch, my garden becomes weed choked. With mulch, only a few weeds manage to get through.
10- Mulch saves me time! While it takes time to make and spread mulch, it's nothing compared to the time I would have to spend watering, chopping weeds, digging dry hardened soil.
11- Mulch helps save me the cost of fertilizer. While I do also use compost, mulch contributes to soil nutrients.
12- Mulch rototilled into the soil between crops helps control root knot nematode.
13- My garden produces a whole lot more food for us when it is kept mulched, I have tried gardening both ways, and a mulched garden produces more food in my experience.
So, what do I use for mulch? Well, it depends upon the crop and what is available at hand.
1- Grass clippings. I love grass clippings as an all around mulch. It's easy to apply, is high in nutrients, and rototills into the soil easily. It is also easily available for me since I live near macnut farms where I can mow grass if I need it. But it is time consuming to mow by hand, even with a self propelled hand mower. Eventually I would like to buy a riding mower that bags the clippings. It is definitely on my "want list".
2- Weeds, bush trimmings, tree leaves, other plant material. I usually run this stuff over with the lawnmower, making a nice mulch. It is coarse, but that doesn't matter. I use to run this through a shredder but I found that the lawnmower was far faster.
3- Tree and bush prunings run through the chipper/shredder. It's a bit coarse, but quite useable.
4- Utility line chippings. The utility companies ocassionally prune their right of ways and chip the material. It is coarse but makes an ok mulch.
5- County mulch. I use to have access to the chipped mulch the county made out of green waste. It was great stuff. But alas, it is now located a two hour drive away. Too far.
6- Newspaper. When I am short on clippings, I will put down a layer newspaper then cover it in a thin layer of clippings. It extends the clippings quite nicely. The newspaper mostly rots down between crops, and what's left just gets rototilled in. With young seedlings, newspaper can help provide them some protection until they are big enough to handle a deep mulch of clippings. In this case, I lay down the newspaper and hold it in place with handfuls of soil.
7- Cardboard is useful for trees, bananas, and long season crops like tomatoes. It takes longer to rot away than newspaper. I cover the cardboard with a light layer of clippings.
I have never tried using plastic or commercial weed barrier fabrics. Why? They cost a lot more money to buy than the gasoline I use to make mulch. They do not go away, even though they shred and break up. I'm not sure that plastic allows the soil to develop a heathy ecosystem nor allows rainwater to adequately enter the soil. And the weed barriers I've seen used don't do such a hot job at stopping weeds. But far worse than any of that, it would greatly interfere with my ability to rototill between crops. And sadly, they would do zero to providing nutrients to the garden. So I'll stick with my natural mulches!