Mulch

Mulch can be anything placed on top of soil to cover and protect it.

​Naked soil is vulnerable to erosion, weed seeds, compaction, and water waste. Mulching provides many benefits:

• Reduced water waste
• Temperature stabilization
• Reduced weed populations
• Reduced erosion and topsoil loss
• Improved soil structure and fertility

Perennial plants protected by a mulch of free wood trimmings

So, what makes a good mulch? 

A good mulch allows air and water to pass through easily, while blocking the sunlight needed by weed seeds for germination. Obviously, gravel fits that description, but do you really want to pick out all those rocks at planting time? Or, what about black plastic landscape cloth - doesn’t that do the same thing, without all the work? No, it doesn’t. Ultimately, the plastic will break down, allowing weeds easy access and adding chemicals to the soil. Instead, take advantage of natural processes and use plant-based mulches. They add nutrients and improve soil structure as they break down and they can often be found for free!

• Chipped and shredded tree trimmings--Most tree trimming companies are happy to give away full or partial truckloads of perfectly good mulch. Just be sure to inspect the material for palm tree pieces before it gets dumped on your driveway! Coarse wood chips make an ideal mulch. They break down slowly, improving soil structure and feeding the soil microorganisms that make plant life possible.
• Compost--Compost that is placed on top of the soil becomes a highly effective, nutrient rich mulch. 
• Grass clippings--Grass clippings are a nitrogen-rich mulch, which may lead to temporary nutrient fluctuations. Don’t leave them in piles, however, as they will stink to high heaven and may spontaneously combust!
•  Leaves--Rather than sending deciduous leaves to the landfill every autumn, they can be used as an excellent mulch or added to the compost pile.
• Pine needles--If you have a friend with a pine tree, they would probably be very happy to get rid of the needles. Pine needles are excellent mulch because they break down very slowly. Despite popular opinion, green pine needles only slightly alter soil pH and dried needles do not acidify it at all.
• ​Plant trimmings--As you work in the yard, you can create instant mulch with the chop and drop method. Simply chop up whatever you are pruning, right where you are, and let it fall to the ground the way nature intended.
• Straw/Hay--Local feed stores will occasionally offer free hay or straw that has gotten wet, making it unsellable. It still makes a great mulch, so long as it is spread while still wet. Wet hay bales have been known to smolder and burn, or even explode. Believe me, I speak from experience.

How to apply mulch

Mulch should be applied 2"–6” thick, depending on particle size. Smaller pieces fit together more closely, so you don’t need as much as for larger bits. If weeds are a serious problem, or you are eliminating a lawn, it is a good idea to use a really thick layer of wood chips. Be sure to keep mulch several inches away from trunks and stems. If mulch is in constant contact, problems such as crown rot can occur.

As worms, beetles, weather and microorganisms breakdown the mulch, you will need to add more mulch, usually every 3–5 years.